M1KTA's QRP ham radio blog

2SCxxxx replacements

2012-01-25T07:50:00.001Z

I have seen a few posts on lists about possible 2SCxxxx replacements and chinese fakes and as some know I build a lot and I have used these before I have been asked to test a few supplier options one being the ebay trader most know. I'll put these into a simple TX (the Junk Box Special) and an AB linear and test CW and SSB on bands between 0.5MHz to 30MHz which is where the original 2SCxxxx were used without problems. The results will then be put up here.

I might even go as a far as the push pull 2sc2166 linear designs.

AFS Contest CW 2012

2012-01-24T21:49:00.001Z

I got talked into entering the AFS Contest CW 2012 by the Camb Hams group

Contest :AFS Contest CW

Submitted :Tue Jan 24 21:44 2012

Deadline :Tue Jan 24 2012

Section :ALL

Callsign :M1KTA

Group :Camb-Hams

QSOs :80 and one dupe.

DXCCs :3

My audio

I made 80 qso on cw and 3 DXCC during the 4 hour contest, hardly a thrilling rate but added my bit to the group.

Was FT897 @ 20W (So not qrp, I tried but at 5W but in a session just prior to contest was confirmed would have had a hard time so increased output to 20w and contacts were possible) to a G5RV centra at 18ft AGL ends about 6ft AGL.

Bringing up the rear making 79 qso after 1 dupe 1/2 the count of most and 1/3-1/4 rate of the 'leaders' if I heard some the serials been given out correctly, however, 'cut numbers' confused me a little initially. I recorded the contest (just my audio in/out) and might be worth checking I got the serials right before submitting.

Bob (G3PJT) was not kidding about needing sharp elbows, an hour in and you just got stomped on and my 500Hz filter did not seem narrow enough I think I might invest in a 300Hz filter for the FT897 or homebrew something. I heard from another with a IC-7000 the DSP was working overtime to keep everything outside the passband out of their ears, but the AGC was suffering - at times despite basically no audio, the S-meter was showing S9+20.

My exchange was often M1KTA 599 my serial PSE CFM their serial TU, so I programmed that into wintest, seemed to be a few exchange variants in use.

I think many were more or less on the standard Win-Test set, removing the ++ and -- speed change operators, and sure some stripped down a couple of spaces between RST and serial number. -Speed demons!

So normally, in run mode it should have been:

CQ M1KTA M1KTA TEST
Listen for caller
[Optional, but frequently used: G1AB?]
G1ABC 599001
Listen for his serial number
TU M1KTA
Listen for next caller before CQ again

And in S&P:
Find station (there were loads!)
M1KTA
Listen for M1KTA 599 123 or similar
Should have sent
599002
But often sent
599 my serial PSE CFM their serial
Listen for TU

Also had the usual other macros to send repeats of the serial number, "NR?", their call, our call and so on, but the ones above were the normal set. I think it is possible to run wintest to do a lot of this automatically but being a bit dim to set it up correctly.

No doubt not confirming I heard their number correctly will lose a few QSOs in adjudication, in combination with CWGet's attempt, I had two values to choose from. If both were the same, we were happy; if differed, I asked for a repeat!

I gave up trying to cq as I was too slow for those that responded even about 3.580. I have to say, most stations were very patient in the face of my mistakes, and many would quickly increase their letter spacing if I didn't get their call the first time. No doubt a few (reasonably enough) got impatient and wandered off before I worked them, but that's fine.

I predict I'll come last :-).

My full log is:

START-OF-LOG: 2.0
CREATED-BY: Win-Test 4.7.0
CONTEST: RSGB-80M-CC
CLUB: camb-hams
CALLSIGN: M1KTA
CATEGORY: SINGLE-OP 80M LOW CW
CLAIMED-SCORE: 79
OPERATORS: M1KTA
CLUB: Camb Hams
NAME: Dominic Baines
ADDRESS: 34 Bury Road
ADDRESS: Stapleford
ADDRESS: Cambridge CB22 5BP
SOAPBOX: My 1st time and you need sharp elbows after an hour or so as the 
SOAPBOX: frequencies get a bit packed.
QSO:  3525 CW 2012-01-08 1403 M1KTA         599 0001   G4ODB         599 001   
QSO:  3525 CW 2012-01-08 1405 M1KTA         599 0002   M0TCL         599 001   
QSO:  3525 CW 2012-01-08 1407 M1KTA         599 0003   G3WOV         599 001   
QSO:  3525 CW 2012-01-08 1414 M1KTA         599 0004   G0LZL         599 018   
QSO:  3525 CW 2012-01-08 1415 M1KTA         599 0005   G0TPH         599 022   
QSO:  3525 CW 2012-01-08 1417 M1KTA         599 0006   G3SJX         599 024   
QSO:  3525 CW 2012-01-08 1422 M1KTA         599 0007   G3LIK         599 027   
QSO:  3525 CW 2012-01-08 1424 M1KTA         599 0008   G4CKH         599 033   
QSO:  3525 CW 2012-01-08 1426 M1KTA         599 0009   G4ARI         599 039   
QSO:  3525 CW 2012-01-08 1432 M1KTA         599 0010   G3OPY         599 051   
QSO:  3525 CW 2012-01-08 1435 M1KTA         599 0011   G3LVP         599 038   
QSO:  3525 CW 2012-01-08 1439 M1KTA         599 0012   G3LDI         599 053   
QSO:  3525 CW 2012-01-08 1447 M1KTA         599 0013   G3LUW         599 034   
QSO:  3525 CW 2012-01-08 1451 M1KTA         599 0014   G4DQP         599 026   
QSO:  3525 CW 2012-01-08 1453 M1KTA         599 0015   M1BXF         599 032   
QSO:  3525 CW 2012-01-08 1455 M1KTA         599 0016   G4WUG         599 058   
QSO:  3525 CW 2012-01-08 1456 M1KTA         599 0017   G0TPH         599 068   
QSO:  3525 CW 2012-01-08 1458 M1KTA         599 0018   G3RTE         599 082   
QSO:  3525 CW 2012-01-08 1500 M1KTA         599 0019   G0LHZ         599 055   
QSO:  3525 CW 2012-01-08 1501 M1KTA         599 0020   G3XVR         599 077   
QSO:  3525 CW 2012-01-08 1502 M1KTA         599 0021   G0DVJ         599 083   
QSO:  3525 CW 2012-01-08 1504 M1KTA         599 0022   G3UFY         599 078   
QSO:  3525 CW 2012-01-08 1506 M1KTA         599 0023   G0MTN         599 104   
QSO:  3525 CW 2012-01-08 1507 M1KTA         599 0024   G3ZVW         599 084   
QSO:  3525 CW 2012-01-08 1509 M1KTA         599 0025   G0AAA         599 106   
QSO:  3525 CW 2012-01-08 1511 M1KTA         599 0026   G4BCA         599 096   
QSO:  3525 CW 2012-01-08 1514 M1KTA         599 0027   G4BJM         599 126   
QSO:  3525 CW 2012-01-08 1516 M1KTA         599 0028   GW3SQX        599 104   
QSO:  3525 CW 2012-01-08 1517 M1KTA         599 0029   G3TBK         599 132   
QSO:  3525 CW 2012-01-08 1519 M1KTA         599 0030   G3ZGC/A       599 115   
QSO:  3525 CW 2012-01-08 1520 M1KTA         599 0031   G4PIQ         599 129   
QSO:  3525 CW 2012-01-08 1521 M1KTA         599 0032   G3RXP         599 121   
QSO:  3525 CW 2012-01-08 1523 M1KTA         599 0033   GM3WOJ        599 120   
QSO:  3525 CW 2012-01-08 1524 M1KTA         599 0034   G3LZQ         599 110   
QSO:  3525 CW 2012-01-08 1526 M1KTA         599 0035   G4BUO         599 121   
QSO:  3525 CW 2012-01-08 1527 M1KTA         599 0036   G3PND         599 078   
QSO:  3525 CW 2012-01-08 1529 M1KTA         599 0037   G7VJR         599 104   
QSO:  3525 CW 2012-01-08 1532 M1KTA         599 0038   M0PTO/P       599 028   
QSO:  3525 CW 2012-01-08 1536 M1KTA         599 0039   G3JRM         599 078   
QSO:  3525 CW 2012-01-08 1537 M1KTA         599 0040   G0BBL         599 074
QSO:  3525 CW 2012-01-08 1540 M1KTA         599 0041   G3SVL         599 100   
QSO:  3525 CW 2012-01-08 1543 M1KTA         599 0042   G4FSU         599 112   
QSO:  3525 CW 2012-01-08 1544 M1KTA         599 0043   G4BYG         599 128   
QSO:  3525 CW 2012-01-08 1546 M1KTA         599 0044   G3SWC         599 124   
QSO:  3525 CW 2012-01-08 1548 M1KTA         599 0045   G3DTZ         599 097   
QSO:  3525 CW 2012-01-08 1551 M1KTA         599 0046   GM4FAM        599 128   
QSO:  3525 CW 2012-01-08 1552 M1KTA         599 0047   G3RVM         599 163   
QSO:  3525 CW 2012-01-08 1554 M1KTA         599 0048   G3VYI         599 146   
QSO:  3525 CW 2012-01-08 1559 M1KTA         599 0049   G4SGX         599 059   
QSO:  3525 CW 2012-01-08 1601 M1KTA         599 0050   GW0GEI        599 138   
QSO:  3525 CW 2012-01-08 1603 M1KTA         599 0051   G4AFS         599 136   
QSO:  3525 CW 2012-01-08 1605 M1KTA         599 0052   M0DHO         599 155   
QSO:  3525 CW 2012-01-08 1607 M1KTA         599 0053   G4CWH         599 140   
QSO:  3525 CW 2012-01-08 1608 M1KTA         599 0054   GM4SID        599 124   
QSO:  3525 CW 2012-01-08 1610 M1KTA         599 0055   G4DJX         599 185   
QSO:  3525 CW 2012-01-08 1612 M1KTA         599 0056   G3UJE         599 175   
QSO:  3525 CW 2012-01-08 1614 M1KTA         599 0057   G3BJ          599 188   
QSO:  3525 CW 2012-01-08 1616 M1KTA         599 0058   G0CKV         599 143   
QSO:  3525 CW 2012-01-08 1619 M1KTA         599 0059   M0UNN         599 166   
QSO:  3525 CW 2012-01-08 1620 M1KTA         599 0060   G3NKC         599 180   
QSO:  3525 CW 2012-01-08 1624 M1KTA         599 0061   G3VDB         599 152   
QSO:  3525 CW 2012-01-08 1626 M1KTA         599 0062   GM4AFF        599 162   
QSO:  3525 CW 2012-01-08 1630 M1KTA         599 0063   G6MC          599 193   
QSO:  3525 CW 2012-01-08 1633 M1KTA         599 0064   MM0ROV        599 097   
QSO:  3525 CW 2012-01-08 1635 M1KTA         599 0065   GM4ZUK        599 150   
QSO:  3525 CW 2012-01-08 1640 M1KTA         599 0066   G4TSH         599 193   
QSO:  3525 CW 2012-01-08 1644 M1KTA         599 0067   G3TJE         599 148   
QSO:  3525 CW 2012-01-08 1647 M1KTA         599 0068   G3YLA         599 122   
QSO:  3525 CW 2012-01-08 1648 M1KTA         599 0069   G3TXF         599 214   
QSO:  3525 CW 2012-01-08 1655 M1KTA         599 0070   G3RKF         599 113   
QSO:  3525 CW 2012-01-08 1657 M1KTA         599 0071   G3KLH         599 189   
QSO:  3525 CW 2012-01-08 1700 M1KTA         599 0072   G3KNU         599 138   
QSO:  3525 CW 2012-01-08 1707 M1KTA         599 0073   G3RWL         599 178   
QSO:  3525 CW 2012-01-08 1715 M1KTA         599 0074   G3PJT         599 196   
QSO:  3525 CW 2012-01-08 1718 M1KTA         599 0075   GM0WED        599 165   
QSO:  3525 CW 2012-01-08 1722 M1KTA         599 0076   G4ZUL         599 160   
QSO:  3525 CW 2012-01-08 1725 M1KTA         599 0077   G7TWC         599 123   
QSO:  3525 CW 2012-01-08 1728 M1KTA         599 0078   G3ZBU         599 116   
QSO:  3525 CW 2012-01-08 1731 M1KTA         599 0079   G3PYE         599 168   
QSO:  3525 CW 2012-01-08 1734 M1KTA         599 0080   G4KZD         599 154   
END-OF-LOG:

Great new Manhatten/SOTA blog

2012-01-17T08:07:00.003Z

You have to take a look at this blog. http://m0cgh.blogspot.com/ The images and constructions are simply great.

The comment I had from Colin was..." I have just started to do a blog ... I've never done a blog before, so I'll just have to see how it goes."

Well Colin doing very well so far. 72 Dom M1KTA

N2PK VNA Build

2012-01-06T07:54:00.001Z

I made a start on a N2PK VNA last night. I had a spare PCB and parts from a group buy back in 2005.

Just a couple dozen of the discrete C fitted so far.

I have a new PC motherboard arriving tomorrow for a quad CPU I have and the motherboard has a native LPT port and COM port and I will build the system just for the test bench as I will also run a digital oscilloscope and other various com and lpt based test kit with it.

I also have the newer N2PK V5 PCB http://www.makarov.ca/vna_v5.htm arriving soon which has a second detector and can plug into a USB port. I'll build up both versions side by side and probably compare them... then apart from the other builds I really must advance some more on the PIC-A-STAR's.

Now where did I put all those SMA connectors?....

Change rockmite (not 20m) 30m PA

2012-01-03T18:17:00.001Z

Original unmolested.

Going to have a bit of fun with a rockmite kit I have unfinished.

I think it is 20m but might be for 30m I have the SCAF filter boards with it too.

I'm going to play about with the pa and see what is possible.

Then time to play with what a PP3 battery can do with a rockmite.

I'll update this post or create a new one with the results.

It was a 30m kit... Q6 (PA) was already soldered in but I'll chop it out, add some turned sockets (and something for bias if using a FET) and try some PA fun and games. In the meantime I also added a VXO mod (Xtal freq 10.116), I'll include schematic details later but pictures here...

Note I added shrink wrap to the multiturn resistor connections.

Yes I really have glued two pads to the top of the AF chip :-)

I bought a whole box of random pots and multiturn pots at GQRP Rishworth 2011 and this is a 20k 10 turn Bourns pot.

The VXO mod is from KE2SP. The details are on the rockmite yahoo group but here they are as well.

These two images are the board before and after modification.

The MV1662 varicap... don't discard it they are like hens teeth. The 5V1 zener you should save and use again another time. The pads on the AF sound chip do not have to be round I have used two 5mm pads but small square off cuts of pcb also work.
The 220K resistor, you can just add a 120K in series with the 100K that is already there.

DC-DC converter

2012-01-01T13:13:00.000Z

After a visit from Johnny SM7UCZ and some exchanges and after santa brought some components (IC,FET and Zeners) I am going to build one of his DC-DC converters for /P valve trips.

My version of the PCB is here

Note I have used TO220 with mounting holes but I'll not etch them or drill them and will solder the tab to the boards.

His original (in Swedish is here)
http://www.sm7ucz.se/DC_DC_converter/DC_DC_Converter.htm

I will use plastic D cell holders and a 30VA transformer I bought from Farnell and I have a big 470uF 450V electrolytic already.

The meters I will use are from John G8BTU

Sussex Valve Tester

2012-01-01T10:47:00.003Z

Just before xmas the parts and the specially wound transformer arrived along with a PCB that needed to be drilled so just finished drilling the PCB.

Dad suggested I need to make a metal brake/bender so that I can work with sheet aluminium (and steel) so ill make up a case for the valve tester.

Johnny (SM7UCZ) also suggested a double triode tester as well.

DL4YHF Counter

2012-01-01T10:25:00.002Z

I bought a couple kits from Sunil http://cqbitx.blogspot.com/p/buy-digital-dail-kit-05.html a while ago and I have just made up the three kits.

http://www.qsl.net/dl4yhf/freq_counter/freq_counter.html is the originating site you need to view.

I'll be using one as a bench frequency counter and combined function generator (XR2206) as I bought a couple XR2206 IC from ebay over xmas.

Another I'll use with an LTC1799 IC which is a simple signal generator. To which I will add attenuation on the output. It will product almost 5V p-t-p square wave.

[another photo]

The last will go into a Norcal40A kit.

500KHz transverter

2012-01-01T10:20:00.000Z

Back on this again and just finished it.

I went with a 7MHz LO and SBL-1 mixer very similar to G3XBM layout but I made a PCB for it.

Elecraft T1 for £10 a 2N3906 and 1/4W 3K3

2012-01-01T10:07:00.001Z

I picked up a T1 thatsomeone built at a rally a while back but was stated to be notworking cost me £10. If really was dead I could use the L match network.

I didn't find a troubleshooting guide tofigure out what the problem is but his is what I did...

All the values, andcomponents 'appeared' to be in theright place etc Resistance checks on page 15 and 22 of the manual seem fine…

Apply power (with PICremoved) and the regulatorsappear to be applying the correct voltages etc..

The section reads:

Use your DMM to make thefollowing resistance checks.If the board fails any of the following checks,

carefully check the positionand orientation of allparts and inspect the board with a magnifier for solder

bridges or missed solderjoints.

Resistance across capacitorC19: between 137 K-ohmsand 148 K-ohms. Press S2 and confirm reading

drops to between 117 K-ohmsand 135 K-ohms.

Resistance between D3 anode(end without the band) andthe “ –“ pad near D7 (ground) where the

black wire is attached: >100 K-ohms (may show openor infinite on some DMMs). Press S1 and confirm

the reading drops to between117 K-ohms and 130K-ohms. If the resistance is higher, try reversing your

DMM leads.

Set your DMM to diode test.Connect the negative probeto either end of resistor R9. Touch the

positive probe to thefollowing pins on J5 and verifythat the diode tester shows approximately 1.6 volts

forward drop across each LED.J5 is the connector atthe opposite end of the control board from R9. Pin 1

is the round pin at the endnear S2. Each LED may alsolight up when the test voltage isapplied (not all

diode testers supplysufficient current to producelight):

__ Pin 1: Red LED ___ Pin 2:Yellow LED __ Pin 5:Green LED

The LED do not light up.And the diode tests fail.

Humm ... scratched head a bit and had a chat with Elecraft and this extra info helped and I include it here in case anyone else have a problem:

Also for starters I had removed the switch bord from the uPC and relay board underneath for the first set of tests.

Make sure the red lead from the battery goes to the + connection neartheunbanded end of the 1N5817 diode at D3. The smaller round positiveconnector onthe 9V battery goes to the battery terminal for this red wire. (That was fine)

The black lead from the battery goes to the - connections between theyellowand red LEDs. (That was fine too)

J4 is the connector on the left side of the T1 control board.

J5 is the connector on the right side of the T1 control board.

Verify the MCU has no bent pins and is fully pressed all the way downin its ICsocket. (OK)

Do you see 6V on pin 1 of the U1 processor when the PWR button istapped? (usethe thumbscrew or BNC jack for ground) (Yes)

You can test this at J4 pin 3, which is the pin just above and betweenthegreen and yellow LED, and it is the 3rd pin when counting beginningwith theround pin 1 of J4. U1 pin 1 and J4 pin 3 are directly connectedtogether.Remember that J4 is on the left side of the control board.

Also, J5 pin 3 should show 9V to ground when the unit is off and S1hasnot been pressed. Remember, J5 is on the right side of the controlboard as youwould normally face the unit. (OK)

When PWR button S1 is pressed and HELD down, J5 pin 3 should be 0VDC. (OK)

If theMCU comes ON and is working, when the S1 button is released, after afew seconds- J5 pin 3 will rise back to 9V . This is when the MCU times out andreturns to"sleep mode", and releases the /HOLD_ON line at U1 pin 5. (I will test later... and it was fine, after I fixed some things but it did not work as it should initially)

This change in voltage at J5 pin 3 and U1 pin 1 and the 6V appearing atU1 pin1 must occur, or something is wrong with the power up circuit of D3,R7, C20,Q1, R14, S1, D4, C19, U2, D4. Check all of those parts and theirsoldering veryclosely. Both U2 (78L06) and Q1 (2N3906) should be installed with theirflatside facing up. (Problem #1 Q1 was inserted backwards so chopped it out and replaced it with a new component the right way around this time)

Be sure U2 and Q1 are not swapped with each other. Besure R7is 120K and R14 is 3.3K.

(Problem #2 1K resistor in place, replaced with 1/4W 3.3K)

Verify all of the parts are in the correctlocations,and are not damaged or unsolder-ed. (OK on parts spent some time going over the underneath solder connections)

Be sure D3 and D4 are not installed in reverse. D3's banded end goestowardR14, and D4's banded end goes toward switch S2. (Both OK)

MCU U1 must be installed with the notched end closest to the J3 remote1/8" phone jack, or to the left as you face the main board. (Problem # 3 the uPC socket and uP were in reverse, so I flipped the uPC and T1 worked fine)

You can use an ohmmeter to check for any shorts between the connectorpins andground with the battery removed, and between any pins of the parts anda nearbyconnection that is not at ground. Note some connections areintentionallygrounded. Use the schematic as a reference for these tests. You canfind anaccidental short circuit or solder bridge this way.

Examine both sides of both PCBs very closely using a bright light and amagnifier. Look for missed solder connections, shorts or solder bridgesorsplashes, etc. Remove any excess solder and clean up any poorconnections asneeded, using Soder Wik and a Q-Tip moistened with acetone or alcoholto cleanthe PCB. (The board was cleaned up a bit)

Do you ever see any LEDs light up when the PWR button is tapped (yellowLED), or if it is held down for more than 1 second (green LED)? (Operating as should now)

Did you verify the LEDs are not installed backwards? You can check themforcorrect orientation by using the diode test function on most DMMs. (Diodes fine)

First remove the 9V battery.

Then place the positive test probe on the anode connections for eachLED atpins 1, 2, or 5 of the J5 connector, and the negative lead on thecommon cathodeconnection at either end of R9.

J5 is the connector on the right hand side of the tuner as you wouldnormallyface the top and front of the PCB (near R21). Pin 1 is the round pinnear thebattery compartment. R9 is near the left top edge of the T1 controlboard.

Each of the LEDs should light enough to be seen in a dimly lit room asyou movethe positive probe to J5 pin 1, 2, or 5 and hold the negative probe onR9.

Thu, 17 April 2008

2011-12-23T15:46:00.001Z

Found some old photos of when I was /P in North Wales.

It was cold and very windy. The wind at the /P site was coming right over the wall and had to weigh the tripod down wityh everything in the rucksack and a couple stones from the wall (that I put back after)

Chess by radio

2011-12-06T20:41:00.001Z

Posted on G-QRP club looking to see if anyone interested in playing chess by radio during the G-QRP Winter Contest.... had a few odd replies and couple off list emails and looks like might be some interesting radio this Xmas.

The idea is not new...

Haverford College on the east coast of the USA was home to some of the earliest college radio experiments, including inter-continental chess matches and quizzes in the 1920s and 1940s. In December 1924, Haverford College and Oxford University had the first international chess match by amateur radio. In 1926, they again held a chess match by radio, this time with students from the University of Paris.

Workshop photos

2011-12-05T09:05:00.001Z

Was asked what does the workshop look like now.... so here are some photos of just the build and test benches.

Postie was busy today... lots of parts

2011-11-29T14:35:00.001Z

Amongst them ...

25uF 400V caps for Sussex valve tester and a new paraset inspired RX only for 80m (I will have to camouflage them to look like Sprague caps)
Rapid order for all the other Sussex parts (except, chassis, transformer, PCB and meters)
Farnell order for the Phasianus colchicus (481THz rxtx)
A couple (one spare) 74HC14 for the ESR meter.
Some PIC-A-STAR parts that have been on back order for a while
Some TI and AD sample chips.

I guess I am going to be melting solder later....

ESR meter - update

2011-11-27T14:14:00.001Z

I also just built the VE7IT/G4EBT/http://www.vintage-radio.net/forum/showthread.php?t=54367&highlight=esr+meter version using vero board layout.

I didn't have a resistor network for the 5 680ohm resistors so I just made one up from 5 discrete resistors.

The circuit calls for a 0.47uF 400V capacitor which provided high voltage blocking/protection in my case is a 0.1uF 630V capacitor. I have a couple 0.22uF and a 0.33uF as well but only to 250V and 275V.

The three 10nF are 50 V the others are either 63V or 100V.

I have to laugh though... I thought I had some Logic 74HC14 IC... well that is what I should have had... what was in the tube in fact were 74HC04 ... oh dear.

I think this meter might be suitable for conversion to a PIC with an LCD readout as it is a simple AC ohmmeter. The signal is applied to RA1 or whatever of a PIC and sensed. I might play with that some more.

The other meter I built earlier I'm going to to box that up this afternoon, along with a simple 555 based 1KHz oscillator.

I was sent this note as my FSD is 44uA.

> Problem right now is the FSD I replaced R17 with 1K8 and pot is at zero and still get no >more than 44uA. I used a 2N2222A.

That's odd. In mine, I used a 3k3 fixed resistor as R17, and a series preset 22k pot to zero the meter. Using a 50uA meter, with the cap test leads shorted, I had no difficulty getting the meter to zero (right hand end of the scale). Yyou've obviously had a poke around with your scope, and might like to check the readings against the following:

From the junction of R8, D5, D6 and C5, there should be a waveform of about 180mV peak to peak, but it’s important to note that this is only when the test leads are shorted, or a good cap with a low ESR is connected to them. This AC waveform then passes via C2 to the base of the 2N2222A which is an AC amplifier with a gain of approx 10.5. It's role in life is to raise the 180mV p-p input to nearer 2 Volts p-p. This then passes to the meter rectifier D1,2,3 &4, for the meter movement. But without the test leads shorted, or a known good electrolytic cap with a low ESR attached to the test leads, there will be zero Volts at the input of the 2N2222A, nothing at its output, so no deflection on the meter. The meter rectifier enables the meter to function as an expanded scale AC voltmeter. Full scale is zero Ohms, midscale is approx 10 Ohms. There is no DC output until approx 75 Ohms of ESR is seen at the test terminals, (ie, a bad cap), at which point the meter will barely deflect.

(The role of the cap C5, stated as 1uF in the VE17T original article but shown on his board as 0.47, is to protect the meter should it be applied across a charged cap. It doesn't have any bearing on the functioning of the meter).

Valve testing.

2011-11-26T16:11:00.001Z

This is an exchange I'd like to share from the G-QRP email list that some might like to read as it contains some information that I found of use...

Hi Dom,

I cannot offer either a valve tester or some spare valves, but the following might help you to cope without a tester..

My working life started in 1957 as a MN Radio Officer, so I cut my teeth on valves. Ships were not supplied with any means of testing valves as such, but We managed adequately without. Generally there are two main types of faults with valves. Either the heaters goes o/c, or the cathode emission reduces.

An o/c heater is easy to check - either there was a lack of glow in the glass or, if necessary, the test meter can be used!

Low emission can be determined by the valve clearly not conducting as much current as it should, determined by "wrong" pinout voltages. The tests are relatively simple.

First check that h.t. is correct. At the time, being too low usually indicated either valve h.t. rectifier gone low emission or a vibrator with burnt contacts. (Ships of the 1950's commonly had d.c. supplies, or possibly the receivers were run from the 24v energency battery supply - hence the need for the vibrator).

Assuming the h.t. was correct the next checks are voltages at cathode, screen grid and anode. Assuming there was some resistance in series with the pin, either cathode volts low, or screen and anode volts high can be taken as general indications of low emission.

The next test was simple to a seagoing "Sparks" - try a new spare valve. Fortunately the "Merchant Shipping (Radio) Rules" dictated that spares were carried to a minimum quantity calculated by a defined schedule. If found faulty, the offending valve was left to swim home!

In some equipment, I have in mind particularly the magnetron in the radar which operated on a very low duty cycle - short high intensity pulses at relatively long intervals, the manufacturer actually wired in a series resistor, duely shunted by a suitable smoothing capacitor, with the handbook stating the correct voltage drop for a valve having normal emission.

If you want to make a tester, don't get too technical as it isn't necessary. Uswe the heater and h.t. supllies from any suitable piece of kit you have and using a spare valveholder wire up the base with suitable values of anode, screen and cathode resistors to vause the valve to conduct a modest amount of current, that is well below full dissipation rating for the valve in question. Measure the current with a milliameter in the cathode circuit (it keeps h.t. from both your fingers and the meter movement). Record readings of anode current, screen voltage and cathode voltage. The voltage at the cathode is in effect the same as the negative voltage at the control grid. Because the cathode is at a few volts above zero, remember to subtract this voltage from the readings you get at anode and screen grid.

Now compare what you get to the characteristic curves for the valve in question, remembering that is the valve was from a "Quality" manufacturer, you can expect the actual characteristic to be within about 5% of the publlished data. If you are getting anode current readings substantially lower than you should for the values of grid (cathode), screen and anode volts, then the valve is low emission.

If you need valve characteristic curves, feel free to ask, as I have quite a lot of valve data books.

I hope this helps.

Alan g3rmz in Plymouth

From: DomBaines
To: GQRP@yahoogroups.com
Sent: Friday, 25 November 2011, 12:02
Subject: [GQRP] Valve tester anyone?
Hi all,

Anyone got a valve tester capable of testing the metal 6??? series of octal tubes 6K7, 6J7, 6SQ7, 6V6GT (OK this one is glass)? Either I could borrow or I could send you the valves and you test them for me? Or I could travel to you in person if local to me... I am in Cambridge and not working right now.

I can test if the filaments/heaters are intact with a meter but that is about it and want to know if any of the valves in my HRO-5 are duff or not. I think most are fine and the AF and IF sections seem to be working, the LO seems to be creating a signal as you can pick it up with a MW radio but it is still not working and the signal is lost in the mixer but not really sure.

The PSU heaters are fine, the HT is fine, the capacitors and resistors seem to be testing fine (although building an ESR meter to confirm that)

Or anyone advise a simple series of tests I could do? I'd feel a bit stupid shelling out for a valve only to fine the original is fine.

I have also thought about trying to build one :-)

http://m1kta-qrp.blogspot.com/2011/11/valve-tester-homebrew.html

Or...a nyone built 'The Sussex VT' valve tester? or got a part build they can spare.

72

Dom
M1KTA

The Sussex VT1 - Valve Tester

2011-11-26T15:51:00.001Z

I'll be building one of these.

See the whole thread here http://www.vintage-radio.net/forum/showthread.php?t=48853 this includes all the details of the build and part sourcing.

I have the PCB coming, parts on aorder, ebay orders out even to hong kong and USA and someone is winding me a transformer. So I might have a test set.....

Now just to create the tables of values for the valves I am using... so will be in the workshop and shack later creating an inventory of them. I suspect a little like Richard G3CWI talk about a VNA in the workshop at Rishworth GQRP 2011 conference, I might end up testing/measuring many of the valves I use rather than building something with them :-)

I'll post images as the build progresses.

HRO-5 underside

2011-11-26T15:10:00.001Z

I've been asked to post more images of the underside of the HRO-5 set so here you go...

Some of the components might 'look' like they were from 1943 but they hide a secret... A number of the Sprague capacitors were literally rebuilt (not by me) and house a modern value inside, the old capacitors were suspended (in an oven I think) until the wax seals melted and the contents fall out, then a new capacitor was inserted and the ends resealed with wax.

There are two visible modern resistors (one is 1/2W other 1/4watt) but the rest are originals that were not 'high'.

The wiring loom was 99% sure completely replaced with new 'look-a-like' cloth covered wire as the original had degraded.

Phasianus colchicus

2011-11-26T14:40:00.001Z

Today whilst out dropping off something at a friend of my wife I was looking for a suitable location for operating at 481THz (optical) and the car right in front of me was hit by a pheasant flying across the road. The car never stopped but the pheasant ended up in the road side about 50 yards ahead of me. Dead obviously. So never one to miss an opportunity I collected it up and the pheasant will go into the pot.

UK law is great in this regard... if you knock something down, technically, if you pick it up, you could be accused of poaching but I suspect very unlikely to be so. However, if the vehicle in front of you knocks something down you are perfectly able to pick it up without fear of prosecution. The Law Is A Ass according to one of Dickens characters so things don't change do they?

Irrespective of the death wish pheasants appear to have around here...this has inspired me to call my opto TXRX build 'Phasianus colchicus', or Common Pheasant.

Some of the following images might not suit every one so if you are not into preparing game then do not read on.

Plucking, start at the head ...

I'll not post the more gruesome images after this one....but this is where food comes from and I was brought up in the country and every time I do a long cycle trip it is amazing what you can pick up and roast on an open fire.

The RXTX circuit and images will follow.

Valve tester - homebrew

2011-11-25T10:53:00.001Z

See my later post about the Sussex VT1 - Valve Tester as that is what I am building.

I have a need to test some valves but no real way (idea) how to do it so as well a checking some old manuals but they mostly just said plug the valve (or tube if was a US book) into the valve tester and check emission etc..... really helpful! So I did a google search brought up a couple of testers that cost more than my whole shack and then I came across this basic circuit which seems really simple. The 2SB546 is a high voltage PNP power transistor I might see what I have that might suit. The comment is any PNP with a Vce of 200 volts or higher. Beta is important here though. It determines the size of the bias resistor (39K 1W). The specified 2SB has a measured beta of 250. The suggestion is to use anything over 100 and preferably over 200 to keep the R small.

You connect the valve pins for K,A, G1-3 and filament to where they are on the above diagram.

It was for a 120V (US) mains supply so I have a UK 240V isolation transformer or a UK-US step down transformer I can use.

The notes on it are:

It can do both an emission test and grid-shift.

For straight emission, just ground-out the g₁.

Because the CCS makes for a high plate-Z, it's prone to becoming an oscillator. The 25uH choke in the plate lead solves that.

No need to filter the supply, which simplifies things and the pulsing DC keeps dissipation very low.

The optional grid-shift tests statically the tubes ability to bias. Can also be used to match tubes (for DC characteristics). Nice compromise between simple emission tester and full-blown transconductance tester.

An additional note says:

But, why not tie g₁ to the plate and g₂ like other testers? There is a problem with this, as shown here

Now I realise I might also need to do something like check the amplification but that comes later maybe. Would be interested in any comments.

More info (from the guy that shared the info http://geek.scorpiorising.ca/GeeK_ZonE/index.php?topic=1803.80 called Gregg) follows this is the full circuit:

This is gonna need explaining. First I'd like to say, keep using the shaver transformers for the HV section as we have outlined in the past. You will need two, one to supply the plate (unfiltered), the second in half-wave for bias and short test. The only reason I've used the cap-filtered version here was to try and simlify the power supply. When I did this before, I eneded up with blown transistors due to the current surge from the cap. The 560 ohm, 5 watt and 330 ohm, 2 watt in there solves the surge, but there are two drawbacks:

- We lose out 100mA scale
- Junction heating above 30mA does cause "creep" in the current.

Why I didn't revert back to the old version of B+ supply is I had already assembled the transformer I wound for it and didn't want to take it apart again

Fusing, use fusing. There are three here, one for the primary, one inline with the CCS (Murphy will make sure your Mullard EL34 will be destroyed to protect the primary fuse if all hell breaks loose) and the fuselink in the ground of the high current transformer CT. I made that from a 6" or so piece of #30 or 32 wound on a drill bit. It changes color at 3A and glows slightly at 5A and can handle the cap-charging surge better than a real fuse. It severs, the whole filament side shuts down

I had a bugger finding 12V DPDT relays for under $10, so I used some 6V ones the local electric place had a surplus bin full of and added a big resistor (56 @ 5W). I just left that value open for your calculations depending on what you have.

The rest of the regulator is straight out of the National Applications sheet. The sheet calls for tantalum input/output caps on the 317. I used the special HF electrolytics for SMPS use with no ill effects. The applications sheet also mentions this needs for stability, a constant 30mA current drain. I tried without, and it does need it. The 2SD414 (or any medium voltage (100V) NPN with a dissipation of 5 watts will do) is referenced to the -16V rail and guarantees a nice 30mA draw from 0.6V to the output's maximum of 56V. It just needs a 5W heatsink.

The pass transistors heat dissipation can be calculated by the V_diff*maximum expexted I draw. I could have used one pass transistor, but already had the two mounted from earlier experiments where they had an 80W total dissipation.

The 3A 1N54xx (did I mis-label them? Are they 58xx? meh) need to be there. As the voltage range switches, we're looking at some difference (up to 8V) being dumped through the caps. 1N4007's blow up.

The range selector, relays and supply voltages are such that there is no more than 24V across the regulator on the high range and about 16 on the rest. Referencing the regulator to a negative voltage on the low range allows the output to go as low as 0.6V, perfect for those weired 0.7V filaments and 0.8V filament Russian VFD's.

The meter resistors on the voltage range switch are fine for any 1mA movement for the output voltages expected. But, there's a twist on mine that I *wouldn't expect anyone else* to do, and that's the "Low Scale Heater Resolution" nonsense. The meter I used for this is very tiny. Yeah, I have bigger ones, but (stubborn Dutchman mode) I liked this one. On the low scale and with this switch on (use the other position for absolutely everything else), it makes the meter read 6.3V full scale and the heater voltage adjust only go as high as 6.3V. I did this because it was too touchy on the low, low voltages. It would be bad indeed to be testing a friends expensive something-or-other with 2.5V filament and blow it because someone across the hall sneezed.

I custom made a meter faceplate for this and has the points marked for all common filament voltages.

The current shunt for the meter will be different for anyone else's though. The meter I used was from a 30's vintage VOM and had the internal resistance calibrated in such a way, common 10% resistors could be used to make the VOM (one of the reasons I liked *this* meter). So, don't expect these everyday 5% values to work for your meter, unless you're lucky.

I scale and CCS... we've covered this before and is the same. But the meter scale for this is worth mentioning - because of the predictability of plate current, rather than making "50%" the pass mark, I've made 80%+ the pass mark, 60-70% a questionable and below 60% a fail. Choose the positions well, small hi-mu tube, little current. At 1mA, it's safe to test tubes with a 90V maximum plate voltage, because the tube draw will pull it down. Higher settings will dump twice that on it and the poor tube unable to pass that much current to pull the voltage down will make the SS gods happy.

Bias control. I've given the tester two bias ranges, 0 to -15V and 0 to -100V for testing high/medium mu and low mu tubes respectively. In the normal position, the gid will be at 0V. Great for testing emission/life/merit, whatever ya wanna call it. Now, we can deduce from curves (or known good tube) at what voltage it should cutoff at, for a given plate current. Just dial this up on the bias and shift the grid. Unless it nosedives below 10%, the grid fails. Because it is operated in a linear mode, I've made "tick marks" on the meter to be used as a way to match tubes at different points. We know better, but it helps to be able to say "ZOMG! MATCHED PAIR L@@K!!!!" and be able to back it up with numbers.

The short test is borrowed from plenty of other tube testers as it's accurate and elegantly simple. A working tube of anykind will have a diode effect. The neon bulb is fed through a cap which acts as a dropping resistor (with some help from a 6.8K resistor because darn it, I just ran out of 0.08679376945 uF caps yesterday) and goes straight to the plate (or other element being tested). If the tube is good, you'll only see a little flash as the cap charges. If it's shorted, the neon lights continuously.

Socket schema isn't here. Paralleled pins to banana jacks are boring. The ones I stuffed into this are, 4-pin (2A3, etc.), 5-pin (807), 6-pin (eye tubes), 7-pin transmitting (829B, 6C33C), 7-pin minature, locktal, octal, 9-pin minature, 9-pin magnoval and 12-pin compactron.

Here's a trick... Use 10 banana jacks. Pins 1 and 12 on a compactron are always heater. Tie them straight to heater and ground. Tie pin 11 to banana jack pin 1. Pins 2-10 are as is, pin 11 = jack 1

Another builder put up his font panel, I can see there are B9A and Octal bases and couple others possible.

I have also been advised to look at http://www.vintage-radio.net/forum/showthread.php?t=48853

ESR Meter

2011-11-24T19:35:00.001Z

The fault diagnosis on the HRO has lead us to belive it might be a failed detector valve and I do not have a spare 6SQ7 or one of the capacitors has gone... so building an ESR meter.

Measuring a capacitor’s ESR (Equivalent Series Resistance) is a great way to assess the condition of a capacitor, vintage or not, particularly electrolytic capacitors .

The design isn't mine, it is based on a series of op amps (TL082, I'll use TL072) that feed a reading into a 100uA meter... (I bought a few 50, 100 and 500uA off ebay a while back) and everything was from the junk box and was cribbed from a old radio magazine. It also has an audible alarm too. I had to substitute a couple components, homefully they will not be too critial but I can replace them if needed.

Not boxed up yet and just built on a off cut of vero board.

I used sockets for the TL072 but did not have any 8pin sockets so used 14 pin sockets instead.

I'll post some more photos of it and maybe an MP4 video of it working.

BTW you can use an ESR meter for more than just measuring electrolytic capacitors see here for more info
http://www.electronicrepairguide.com/esrmeter.html

After I had already almost finished building I also found this page on the web.
http://kakopa.com/ESR_meter/

Like that author I didn't want to go and buy an expensive meter when I could build one for pennies and have fun and learn something new in the process.

HRO-5 and Russian Pencil Valves

2011-11-24T07:56:00.001Z

Hoping to fix my HRO today.... Clive M5CHH is coming over with his and will do a side by side comparison and fault finding to see what might be wrong.

In the meantime I am also looking to build an RX, TX or TRX for other ham band certainly 80m based on the 1b24b or 1sh24b tubes (aka Sputnik) and I am reviewing a few options. There are some great designs out there already but I'd advise you start maybe here http://www.techtir.ie/blogs/watty/miniature_valves_2 and http://www.oldradioclub.ru/radio_book/book/berg/berg.html for technical details of the valves. I especially like these.

http://www.techtir.ie/sites/default/files/u1000004/sweetheart/tatiana-sch-1.png

http://www.hi-ho.ne.jp/ux-45/russian.html If you use Google chrome is can do a Japanese to English translation... bit off but readable.

http://aa1tj.blogspot.com/2010/12/solidarity.html

http://dl3jin.de/tx_1x_1p24b.htm

DL4YHF Frequency Counter by VU3SUA Sunil Lakhani

2011-11-23T19:55:00.001Z

I bought a couple (3) kits from Sunil http://cqbitx.blogspot.com/p/buy-digital-dail-kit-05.html and the package arrived today.

It has been sent over in this amazing cloth and wax sealed package.

Opening it was like that kids game of pass the parcel as there were multiple layers before one arrived at the components.

I'll build these up soon.

http://www.qsl.net/dl4yhf/freq_counter/freq_counter.html is the originating site you need to view.

I might attempt this mod
http://f8fii.com/ModFreqe.html

My HRO-5

2011-11-21T15:01:00.001Z

Was asked to post some images of the insides...

GQRP Valve Day 2011 (20th November)

2011-11-20T13:08:00.001Z

The line up this year... HRO RX, Homebrew 'Scounger' 6V6 TX with crystals and components from all over. My 'new' valve rig is a Codar AT5 which is 80m and 160m CW and AM. antennas are a G5RV (very soggy and will not tune too much condensation in air) and a 6BTV vertical.

Here I'm setting it up the Codar AT5 after cleaning up the inside a little. The meter is duff so I was hoping to swap in a new 100mA meter but although hole and mount screws match the meter is too big... rats so it is sitting by the rig. I get the dip on the meter on the right for now.

I put a plea into GQRP list to see if anyone might have had one of these meters in the junk box and seems I'm lucky so hopefully will not be operating this way too long.

This is the other operating bench, FT897, MFJ993 tuner (top left almost out of picture), I use a Winkey interface with the valve TX and Wintest s/w on the laptop. PSU is a Sharman Multicom PS-SPS250A (switch mode supply and no probelms with RFI) and a Palstar PS-04 that runs all the 12V and 5V (I added 5V output to the read) gadgets on the bench.

I just added a run of CAT5e (buried 18" below ground) to the shack and do not use a wifi connection anymore so the shack now has a reliable internet connection and the common mode chokes (FT240-61 torroids) on at each end seem to have stopped any RF causing issues.

MFJ-269

2011-11-17T16:26:00.001Z

Selling a MFJ-269 unit from the shack as I have a surplus unit.

I have run though the calibration process here http://www.mfjenterprises.com/pdffiles/MFJ-269_Calibration.pdf

I will post some photos of the unit here if asked.

K1 Build

2011-11-10T11:38:00.001Z

This time it is for me and it will be a keeper.

It is a four band model and it also has the nb filter.

Workbench variable voltage/current limited supply

2011-11-06T15:59:00.002Z

I just had a some fun with a circuit that was drawing more current than needed and an electrolytic kept popping so after a rummage in the junk box I thought I'd home brew a variable voltage/current limited supply from a salvaged laptop power supply. It worked and was built Manhatten style, anyway I fixed the problem a bridged joint, on the circuit I was looking at. After use I thought I better put this into something more long term as I am sure I will find use for this and I have a nice salvaged instrument case that it will go into. I had not used the more usual transformer and bridge rectifier but a switch mode supply so I have added a common mode choke on the mains input and the DC output from the laptop power supply into the circuit, which is simplicity itself and comes directly from the LM317 data sheet. I use two LM317 to first limit the current and then adjust the voltage.

Looking at the supply with an oscilloscope (must capture a few images and add them) and after a bit of playing with junk box components I added a 3300uF 63V capacitor to the input and a 2200uF 25V capacitor to the output. I might also add a 250K (ish) resistor across both so that when disconnected from mains the input and output capacitors are discharged. I have several 1000uF 100V capacitors I might add later.

The output is via a pair of combined 4mm sockets and binding posts, I will also add a pair of Anderson Power Pole Connections.

An earth connection has been added that utilises the workbench earth and the circuit ground is also connected to. CARE!!! this might not be recommended for any to copy but I KNOW I have a very good mains earth from the workshop supply at the point it enters the workshop and a separate 4mm earth cable is used about the workshop in addition to the 2.5mm ring wiring.

The input 19.5V 4.22A was selected basically as it was available but the important bit for any such supply is that it should be rated at 1.5 times the output and this would allow this supply to provide 3amps. I cannot remember exactly where I heard this but I have not included a 3 amp option and the supply will limit to 1.5 amps, which is also the limit of the LM317 I have used. I could add a pass transistor and obtain a higher current rating.

I will add the circuit but a quick look at the LM317 data sheets (google for LM317 data sheet) will show the options available.

Setting the current limit:
The current limits are set by connecting the ADJ and the OUT of the first LM317 through a 12 way ceramic rotary switch each position of which contains a low value wire wound resistor selected from a recent rally '50p lucky bag', I could have used 1/2W and 1W carbon resistors too. I also purchased a set from JABDOG. The current limits I have set are 25mA, 50mA, 62.5mA, 100 mA, 166mA, 250mA, 460mA (odd resistor value), 500mA, 1.2A and 1.5A the output current limit is directly related to the formula I = 1.25/R where R is the value of the resistor in ohms. The output is taken into the voltage stage from the ADJ port with the resistor connected through the switch as described connected between ADJ and OUT.

Note that the voltage at this stage is the supply voltage minus the 1.25V drop across the LM317 this LM317 never seems to get hot.

I tested the current settings by feeding this output into a 12V halogen bulb that will run at 50W so is rated well above the power supply with a current meter in circuit.

Voltage Setting:
The variable voltage is set by the second LM317 by adjusting the resistance R1 that is connected from the ADJ port of the LM17 to the ground so that Vout = 1.25 * (R2/R1) where R2 is a fixed 270 ohm 3W wire wound resistor connected between ADJ and the output port of the LM317. The voltage can be varied between 1.2V and 17.3V.

I allowed the supply to feed the 12V halogen bulb at 500mA and left it running for about 4 hours and then remeasured both the voltage and current levels and saw no major changes. At 12V 500mA the LM317 will need to be able to dissipate the heat so I used TO220 version and bolted them to the front panel. The lower the output voltage the more heat is dissipated.

I have not added a meter to measure the current output as the limit is set by switch, the output voltage is another matter and I have employed a 3" chinese analogue meter that looks a bit retro (I might remake the scale).

Photos and circuits to follow.

QRP Sputnik from M1KTA

2011-10-16T18:34:00.001+01:00

A bit late to the party but building my sputnik after Mike AA1TJ http://aa1tj.blogspot.com/2011/07/sputnik-qso-party-transmitter-prototype.html had sent me a pair of valves.

I pretty closely followed Rogers and Andy's layout.

http://g3xbm-qrp.blogspot.com/2011/09/sputnik-valve-tx-tests.html

Mine is here.

This is just part way through the build, manhatten style. I amended a couple of components. Got to add the key and power lines including the resistor drop for V1.

The PSU starts off as a 24V AC supply (Maplin) that is voltage doubled and rectified to c71.9V DC and following advice from G6ALB, Andy I will negative block key the TX so the same PSU generates -36.4V DC. I botched the original build and let out lots of magic smoke as I connected the diode generating thenegative voltage across the AC input... oops! Once built I ran if for 45 minutes just to make sure I had not killed anything else. I added a second LED (green) to the negative output so I can confirm both the main HT and the negative.

The circuit is:

Note I did not have any 100V electrolytics for the last output stage so I used the practice of doubling up the capacitors to get an adequate voltage rating and put two in series rated at 63V each with 100K bleed resistors on both. So you see 4 on the circuit not 3 as per diagram.

The HT PSU was built into a small potting box.

The rig I have built into a nice Hammond enclosure as I had already cut some PCB and it just slides in. The enclosure is one where one side slides off as I am sure I'll need to adjust those variable caps. I did start with a ceramic variable C for C1 but it was too big to fit.

Not quite in a straight line but the 4mm sockets are (Black) GND, (Red) +HT, (Blue) 1.2V for the heaters and a BNC, you can see a phono socket on the other end for the key. I will add the -36V key block 4mm socket to the other end later.

SR63ng build

2011-09-28T21:47:00.000+01:00

Well I am building and I came across this site.

http://www.vk2zbb.com/index.php/sr63ng

It doesn't go through the build stages as per Robby's instructions and is a sequence of placements of every component on the PCB but I'd recommend anyone building to take a look at it.

SDR homebrew project that covers VHF/UHF/SHF frequencies?

2011-09-24T20:50:00.001+01:00

As I push solder around a board that could be used at 70cm I thought... I wonder if there any interest in an SDR homebrew project that covers VHF/UHF/SHF frequencies?

I mean 70MHz up so 70MHz, 144MHz, 432MHz and 1.2GHz (maybe even 2.4GHz).

Frequency agile, meaning not single LO frequency.
Using Silicon Labs Si570 (e.g.http://www.silabs.com/Support%20Documents/TechnicalDocs/si570.pdf), might need modification to the circuits to obtain the quadrature LO required at SHF (An LO at 4 times 1.2GHz or 2.4GHz will be beyond the Si570). Maybe look at Analogue Devices DDS?

Display and Control (PC software aside) by
4x20 LCD or 128x64 GLCD (or better)
Rotary and push button front panel controls
PC and non-PC options (i.e DSP processing)
JTAG/ISCP programming options, probably AVR rather than PIC
Stereo CODEC (via USB so no sound card interface if PC involved)
Modes as per usual SDR capabilities including FM.

Might be interesting to see comments.

Building SDR again

2011-09-24T19:16:00.002+01:00

In advance of the RSGB conference in October I am putting together a new SDR setup and I have just been sent two of the SMT versions of Tony Parks excellent SR V6.3 from Yoyodyneconsulting

http://www.yoyodyneconsulting.ca/pages/SR63ng%20Information.html

It is called the SR63ng and it is a near clone of TonyParks' retired SR63RXTX board where the board has the same physical dimensions and connectorregistration as the original. This mans it will be a direct plug in replacement for the original. One noticable thing is it differs from the original in the useof surface mount components (SMT) rather than axial leadedresistors/caps, which make the build cleaner.

Why am I building these: To provide the RF 'deck' to use the American term for the MOBO-4.3 system as I am building another pair of them (I sent one out and it went missing) and I have managed to obtain a couple of PCB for it as well. This time I will use with the SDR Widget, that was still in Alpha last time, so this will mean no audio output to a PC sound card will be required and will use a single USB connection only. Should have a at least 48/96kHz bandwidth and be frequency agile as it is based on the Si570 DDS but the MOBO will contain a limited number of band pass filters ( up to 9) in the amateur bands.

I am hoping to also have this built side by side with the SDR-Cube shortly.

PIC-A-Star meeting

2011-09-11T20:14:00.002+01:00

Today I attended a meeting for PIC-a-Star builders:

>>The Pic-A-Star event will take place next Sunday 11th September between
>>11am and 4pm at the Milton Keynes museum England.
>>
>>Pic-A-Star constructors (whether completed or not) are invited to come
>>along and are also invited to bring their Stars as well; for those who
>>would like any assistance with their build we will have test equipment
>>including spectrum analyser / power attenuator and a calibrated signal
>>generator.
>>
>>I have updated the web page at
>>http://www.radio-kits.co.uk/pic_a_star/event.htm to show where we will
>>be in the museum.
>>
>>See you there,
>>Steve G6ALU - Calvin M1EPM

PTO

2011-09-08T08:00:00.001+01:00

Back in January 2010 I built and blogged a PTO http://m1kta-qrp.blogspot.com/2010/01/pto-vfo.html I threw together using either a Starbucks or a MacDonalds straw as the former and a small brass plug and M5 Nylon bolt that generated a fair bit of interest. It appears Rev George Dobbs from GQRP club referenced it in an October 2011 Practical Wireless article. Anyway after a brief email exchange with George I am going to see if I can create a 'kit' of sorts for the GQRP convention 2011 at Rishworth of all the mechanical parts and the electronics. I'll update the blog with progress. If anyone has ideas then glad to hear them.

The ideal is 100kHz swing preferably not needing more than 3 full revolutions of a tuning knob.
If I have time will be usable for both a direct conversion setup so will be 80m or 40m or will be usable in a superhet type vfo+IF option. (11.0592MHz maybe??)

Slow motion would be nice but I know this is easier (read cheaper) to obtain by using fine threads OR A BIG TUNING CONTROL.
I found using a blass slug not an iron one was easier so that way you work from a maximum inductance and it drops as you insert the brass slug (made the tuning the 'right way' on the tuning knob too!).

Will be either colpitts or vacker type vfo as stable, I am sort of familiar with them and part counts are low.
Active device will be a FET J310, 2N3819 or similar depends what I have a few of.
Caps will be black spot NPO ceramics.
I'll try and see if I can include a voltage stability at 6V or 8V but will wait and see.

There are two main options
1.The PTO assembly sit 'proud' of the main board (pretty much as my original bodge did, and as per George design) or
2. An on board design a bit like the MMR-40 from KD1JV.
Go to qrpkits.com and you'll find docs for it or there was an ARRL article (I might update these with real links)

The assembly needs to turn a rotation into a horizontal motion. There are probably as many ways to do this as there are resistors in a E24 series but in short you move either the coil over the slug or vice versa, the later is easier. George has already whimiscally shown one option using a used up old lipstick for this.

Anyway more later off to work at the salt mines....

Activating Farne Islands EU-109 on Thursday 25th August

2011-08-02T21:22:00.001+01:00

Activating Farne Islands EU-109 on Thursday 25th August.

Post trip notes:

QRV from 10:42 to 13:00 in the end, first qso 15 seconds after sending first CQ and managed a new IOTA myself as well EU-170.

I checked DX spots:

9A4A-@ 14260.0 M1KTA/P mni tks for new one from eu170 gl. 1150 25 Aug England
HA6VH 14260.0 M1KTA/P 1137 25 Aug England
W1OW 14260.0 M1KTA/P EU-109 1057 25 Aug England
EA1DBX 14260.0 M1KTA/P qrp station, tks x qso 1051 25 Aug England

I had to move off 14.260 due to RA0CGY insisting on CQ'ing on frequency I went up to 14.285 and qso with OE6GND before returning to 14.260MHz.

In the end 60 QSO, all on 20m and all SSB. Furthest DX USA.

I'll load all qso to LoTW and I have QSL cards ready to go.

2.5W from FT817 to a W3EDP (84ft long wire suspended from a 10m fishing pole and then as an inverted L, used a 14ft counterpoise, into a 4:1 balun and a Z11 ATU)

The weather got much better by end of time on the island too.

Logistics:

Go to the quay at Seahouses on the Northumbrian coast, catch one of the tourist boats trips around the islands to look at the seals and the sea birds. You HAVE to ask permission from the National Trust warden BEFORE travelling to the island if you wish to activate it. AND even though they do land on the island check with the skipper of the boat that they really will land on the island. No generator ever and battery use only. Nothing can be screwed into the ground and everything must be self supporting. There are two possible islands you can land on Inner Farne (where I was) ans Staple, much further out.

The MVGlad Tidings IV (W Sheil runs the company) took me over to the island (£13 cost) with a couple other brave souls that wanted to see the seals, first thing it was damned wet and pretty miserable on the crossing as it was raining hard. The NT charges £5.30 adult landing fee but as life member no charge... if you go don't forget to take cash to pay it!

Once on the island as you can see from the movie (taken as I started) and the bottom one it cleared up enormously. There are walkways you MUST NOT wander out of as the ground is riddled with Puffin burrows.

Daylight operation between LOCAL time 11am and 4pm (10:00 UTC ad 15:00 UTC) allowed as those are the times the boats land. QRP was fun and great DX possible but 100W would havemade it much easier. Not quite a 'pile up' but constant string of qso from first to last and couple times 2 stations responded at once. I'll analyse the dxcc count later but nothing from G stations but lots from EU and NA.

Been asked several emails can I activate again as 'we were not ready' from one NA station... not this time but might again soon.

RSGB IOTA 2011

2011-07-27T08:24:00.000+01:00

Asked by a few will I be entering? Yes is simple answer. I expect will be QRV 20m and 40m,maybe 80m SSB and CW, running win-test to FT817 and 6BTV or G5RV and an SDR RX. I will have a new audio interface this year and hope to record BOTH sides of the QSO's (only managed the audio in last year!)

The new workshop is 99% there whilst the shack is a bit of a dump right now until I fix that up so I might operate from the workshop... feeder dependant of course.

I know contests are notfor everyone but hope tosee you in the contest.

Note that the 72 QRP marathon is also on so get on the airand work some qrp.

RSGB IOTA 2010

2011-07-23T18:57:00.001+01:00

I entered last year. This was my entry.

I was hit by a few errors that reduced the final score to 43470 from 51009 claimed.

Odd was I came first in category last year, don't think I'll do so well this year :-)
RSGB IOTA 2011 contest is next w/e 30th and 31st July.

START-OF-LOG: 2.0
CREATED-BY: Win-Test 4.5.1
CONTEST: RSGB-IOTA
CALLSIGN: M1KTA
CATEGORY: SINGLE-OP ALL LOW MIXED
CATEGORY-ASSISTED: ASSISTED
CATEGORY-DXPEDITION: NON-DXPEDITION
CATEGORY-TIME: 12-HOURS
IOTA-ISLAND-NAME: [G;GM;GW;M;MM;MW] Great Britain (Main Island Only)
CLAIMED-SCORE: 51009
OPERATORS: M1KTA
NAME: Dom
ADDRESS:
ADDRESS:
ADDRESS:
SOAPBOX: Only 20m and 40m this year. 12 hour entry was still hard work as
SOAPBOX: arrived back day before contests from cycling down the Rhine.
SOAPBOX: Used a remote SDR RX at the house (50m from shack)
SOAPBOX: and monitored the HF bands so selected assisted.
QSO: 14257 PH 2010-07-24 1200 M1KTA 59 0001 EU-005 OE3K 59 0001 ------
QSO: 14252 PH 2010-07-24 1201 M1KTA 59 0002 EU-005 OG5A 59 0003 EU-140
QSO: 14252 PH 2010-07-24 1204 M1KTA 59 0003 EU-005 CR6W 59 0005 EU-150
QSO: 14252 PH 2010-07-24 1207 M1KTA 59 0004 EU-005 E78DX 59 0011 ------
QSO: 14252 PH 2010-07-24 1210 M1KTA 59 0005 EU-005 YL7A 59 0024 ------
QSO: 14252 PH 2010-07-24 1215 M1KTA 59 0006 EU-005 S51CK 59 0015 ------
QSO: 14289 PH 2010-07-24 1232 M1KTA 59 0007 EU-005 SP9LJD 59 0077 ------
QSO: 14225 PH 2010-07-24 1240 M1KTA 59 0008 EU-005 IZ4JMA 59 0081 ------
QSO: 14215 PH 2010-07-24 1242 M1KTA 59 0009 EU-005 OM3TWM 59 0066 ------
QSO: 14147 PH 2010-07-24 1244 M1KTA 59 0010 EU-005 OK2WED 59 0031 ------
QSO: 14163 PH 2010-07-24 1246 M1KTA 59 0011 EU-005 S52WW 59 0070 ------
QSO: 14204 PH 2010-07-24 1249 M1KTA 59 0012 EU-005 YL3FT 59 0065 ------
QSO: 14211 PH 2010-07-24 1252 M1KTA 59 0013 EU-005 HA8IB 59 0022 ------
QSO: 14267 PH 2010-07-24 1256 M1KTA 59 0014 EU-005 UW8SM 59 0100 ------
QSO: 14275 PH 2010-07-24 1257 M1KTA 59 0015 EU-005 YT1A 59 0054 ------
QSO: 7083 PH 2010-07-24 1305 M1KTA 59 0016 EU-005 GM4W 59 0078 EU-005
QSO: 7080 PH 2010-07-24 1306 M1KTA 59 0017 EU-005 EI5DI 59 0091 EU-115
QSO: 7068 PH 2010-07-24 1308 M1KTA 59 0018 EU-005 M8C 59 0072 EU-011
QSO: 7086 PH 2010-07-24 1311 M1KTA 59 0019 EU-005 GM7V 59 0197 EU-010
QSO: 14265 PH 2010-07-24 1317 M1KTA 59 0020 EU-005 4O3A 59 0178 ------
QSO: 14265 PH 2010-07-24 1327 M1KTA 59 0021 EU-005 5B4KH 59 0179 AS-004
QSO: 14056 CW 2010-07-24 1447 M1KTA 599 0022 EU-005 OM3RR 599 0063 ------
QSO: 14042 CW 2010-07-24 1452 M1KTA 599 0023 EU-005 OH6M 599 0084 ------
QSO: 14039 CW 2010-07-24 1456 M1KTA 599 0024 EU-005 RG3K 599 0356 ------
QSO: 14057 CW 2010-07-24 1506 M1KTA 599 0025 EU-005 LZ1BJ/1 599 0306 EU-181
QSO: 14031 CW 2010-07-24 1511 M1KTA 599 0026 EU-005 HG8N 599 0182 ------
QSO: 14134 PH 2010-07-24 1513 M1KTA 59 0027 EU-005 OH1F 59 0158 ------
QSO: 14170 PH 2010-07-24 1517 M1KTA 59 0028 EU-005 AN1C 59 0328 EU-080
QSO: 14229 PH 2010-07-24 1524 M1KTA 59 0029 EU-005 IS0B 59 0474 EU-024
QSO: 14236 PH 2010-07-24 1525 M1KTA 59 0030 EU-005 CT1AHU 59 0101 ------
QSO: 14299 PH 2010-07-24 1529 M1KTA 59 0031 EU-005 JW5E 59 0283 EU-026
QSO: 14293 PH 2010-07-24 1535 M1KTA 59 0032 EU-005 UA3A/1 59 0297 EU-133
QSO: 14240 PH 2010-07-24 1539 M1KTA 59 0033 EU-005 IT9ZMX 59 0437 EU-025
QSO: 14175 PH 2010-07-24 1543 M1KTA 59 0034 EU-005 9A/OM8A 59 0399 EU-016
QSO: 14162 PH 2010-07-24 1548 M1KTA 59 0035 EU-005 SY9M 59 0601 EU-015
QSO: 14127 PH 2010-07-24 1553 M1KTA 59 0036 EU-005 CU2/DF2BR 59 0022 EU-003
QSO: 14130 PH 2010-07-24 1557 M1KTA 59 0037 EU-005 5B4AIF 59 0399 AS-004
QSO: 14155 PH 2010-07-24 1559 M1KTA 59 0038 EU-005 LZ1KFM 59 0136 ------
QSO: 14236 PH 2010-07-24 1606 M1KTA 59 0039 EU-005 SV2CLJ/8 59 0200 EU-049
QSO: 14263 PH 2010-07-24 1615 M1KTA 59 0040 EU-005 LZ1BJ/1 59 0432 EU-181
QSO: 14273 PH 2010-07-24 1618 M1KTA 59 0041 EU-005 TF7X 59 0404 EU-071
QSO: 7153 PH 2010-07-24 1621 M1KTA 59 0042 EU-005 OZ0TX 59 0287 EU-125
QSO: 7148 PH 2010-07-24 1623 M1KTA 59 0043 EU-005 GM1J 59 0395 EU-092
QSO: 7137 PH 2010-07-24 1624 M1KTA 59 0044 EU-005 S52WW 59 0283 ------
QSO: 7140 PH 2010-07-24 1626 M1KTA 59 0045 EU-005 DL8NBJ 59 0023 ------
QSO: 7120 PH 2010-07-24 1636 M1KTA 59 0046 EU-005 SQ9HZM 59 0038 ------
QSO: 7115 PH 2010-07-24 1637 M1KTA 59 0047 EU-005 MM0EAX 59 0434 EU-009
QSO: 7134 PH 2010-07-24 1643 M1KTA 59 0048 EU-005 EJ3Z 59 0350 EU-006
QSO: 7138 PH 2010-07-24 1644 M1KTA 59 0049 EU-005 F5VKT 59 0208 ------
QSO: 7136 PH 2010-07-24 1649 M1KTA 59 0050 EU-005 SQ7OA 59 0182 ------
QSO: 7130 PH 2010-07-24 1651 M1KTA 59 0051 EU-005 TM5KD 59 0065 EU-068
QSO: 7082 PH 2010-07-24 1658 M1KTA 59 0052 EU-005 GM4AGG/P 59 0109 EU-008
QSO: 7059 PH 2010-07-24 1700 M1KTA 59 0053 EU-005 OZ/DO6XX/P 59 0067 EU-171
QSO: 7094 PH 2010-07-24 1702 M1KTA 59 0054 EU-005 DK1AX 59 0133 ------
QSO: 7125 PH 2010-07-24 1708 M1KTA 59 0055 EU-005 RL3BM 59 0310 ------
QSO: 14249 PH 2010-07-25 0522 M1KTA 59 0056 EU-005 UA4CC 59 0126 ------
QSO: 7170 PH 2010-07-25 0528 M1KTA 59 0057 EU-005 IG9/IK2PZC 59 0314 AF-019
QSO: 7161 PH 2010-07-25 0531 M1KTA 59 0058 EU-005 CS2K 59 1745 EU-167
QSO: 7155 PH 2010-07-25 0535 M1KTA 59 0059 EU-005 GJ6YB 59 2577 EU-013
QSO: 7150 PH 2010-07-25 0537 M1KTA 59 0060 EU-005 N1LI 59 1284 NA-137
QSO: 7118 PH 2010-07-25 0539 M1KTA 59 0061 EU-005 IQ3MO/IL3 59 0823 EU-130
QSO: 7106 PH 2010-07-25 0541 M1KTA 59 0062 EU-005 YL7X 59 1104 ------
QSO: 7088 PH 2010-07-25 0543 M1KTA 59 0063 EU-005 OM3TMW 59 0742 ------
QSO: 7084 PH 2010-07-25 0545 M1KTA 59 0064 EU-005 EA2DOT 59 0079 ------
QSO: 7129 PH 2010-07-25 0550 M1KTA 59 0065 EU-005 TF7X 59 1453 EU-071
QSO: 7137 PH 2010-07-25 0551 M1KTA 59 0066 EU-005 S58MU 59 0353 ------
QSO: 7139 PH 2010-07-25 0552 M1KTA 59 0067 EU-005 SP9LJD 59 1274 ------
QSO: 7167 PH 2010-07-25 0555 M1KTA 59 0068 EU-005 VA3YOJ 59 0676 ------
QSO: 7167 PH 2010-07-25 0557 M1KTA 59 0069 EU-005 ES0U 59 0988 EU-034
QSO: 7120 PH 2010-07-25 0609 M1KTA 59 0070 EU-005 SN3S 59 0886 ------
QSO: 7163 PH 2010-07-25 0613 M1KTA 59 0071 EU-005 F5VBY 59 0012 ------
QSO: 14203 PH 2010-07-25 0620 M1KTA 59 0072 EU-005 UW5Q 59 0966 ------
QSO: 14203 PH 2010-07-25 0627 M1KTA 59 0074 EU-005 UP2L 59 0554 ------
QSO: 7108 PH 2010-07-25 0649 M1KTA 59 0075 EU-005 IZ4JMA 59 0536 ------
QSO: 7128 PH 2010-07-25 0657 M1KTA 59 0076 EU-005 IQ2CJ 59 1290 ------
QSO: 7135 PH 2010-07-25 0701 M1KTA 59 0077 EU-005 OK1AYD 59 0058 ------
QSO: 7135 PH 2010-07-25 0702 M1KTA 59 0078 EU-005 DL3CA 59 0016 ------
QSO: 7135 PH 2010-07-25 0704 M1KTA 59 0079 EU-005 PA3T 59 0166 ------
QSO: 7188 PH 2010-07-25 0711 M1KTA 59 0080 EU-005 DJ4MH 59 0044 ------
QSO: 14217 PH 2010-07-25 0717 M1KTA 59 0081 EU-005 YL7X 59 1211 ------
QSO: 7030 CW 2010-07-25 0758 M1KTA 599 0082 EU-005 DR10TCC 599 0812 ------
QSO: 7024 CW 2010-07-25 0801 M1KTA 599 0083 EU-005 OY1CT 599 1314 EU-018
QSO: 7019 CW 2010-07-25 0803 M1KTA 599 0084 EU-005 EJ3Z 599 0939 EU-121
QSO: 7018 CW 2010-07-25 0807 M1KTA 599 0085 EU-005 OK1AYY 599 0123 ------
QSO: 7013 CW 2010-07-25 0808 M1KTA 599 0086 EU-005 GM7V 599 2346 EU-010
QSO: 7012 CW 2010-07-25 0812 M1KTA 599 0087 EU-005 EJ1DD 599 0868 EU-121
QSO: 7006 CW 2010-07-25 0813 M1KTA 599 0088 EU-005 DL4CF 599 0413 ------
QSO: 7021 CW 2010-07-25 0816 M1KTA 599 0089 EU-005 MM9M 599 0284 EU-010
QSO: 7022 CW 2010-07-25 0819 M1KTA 599 0090 EU-005 F5SGI/P 599 0239 EU-048
QSO: 14048 CW 2010-07-25 0829 M1KTA 599 0091 EU-005 SA1A 599 0941 EU-020
QSO: 14050 CW 2010-07-25 0831 M1KTA 599 0092 EU-005 RZ9AW 599 0760 ------
QSO: 14050 CW 2010-07-25 0839 M1KTA 599 0093 EU-005 OK1JOC 599 0125 ------
QSO: 14049 CW 2010-07-25 0844 M1KTA 599 0094 EU-005 RA4WC 599 0269 ------
QSO: 14050 CW 2010-07-25 0852 M1KTA 599 0095 EU-005 IK1QBT 599 0338 ------
QSO: 14049 CW 2010-07-25 0856 M1KTA 599 0096 EU-005 YU1PJ 599 0358 ------
QSO: 14050 CW 2010-07-25 0904 M1KTA 599 0097 EU-005 SM6NOC 599 0224 ------
QSO: 14050 CW 2010-07-25 0906 M1KTA 599 0098 EU-005 OK1AYY 599 0155 ------
QSO: 14050 CW 2010-07-25 0912 M1KTA 599 0099 EU-005 OK2MJF 599 0193 ------
QSO: 14049 CW 2010-07-25 0918 M1KTA 599 0100 EU-005 DJ2AX 599 0127 ------
QSO: 14050 CW 2010-07-25 0919 M1KTA 599 0101 EU-005 YT3H 599 0092 ------
QSO: 14050 CW 2010-07-25 0924 M1KTA 599 0102 EU-005 OK1AY 599 0355 ------
QSO: 14040 CW 2010-07-25 0932 M1KTA 599 0103 EU-005 AO4ZK 599 0092 ------
QSO: 14045 CW 2010-07-25 0936 M1KTA 599 0104 EU-005 OZ/OK1DRX 599 0336 EU-088
QSO: 14050 CW 2010-07-25 0938 M1KTA 599 0105 EU-005 HB9ARF 599 0318 ------
QSO: 14053 CW 2010-07-25 0941 M1KTA 599 0106 EU-005 RX0AW 599 0150 ------
QSO: 14059 CW 2010-07-25 0943 M1KTA 599 0107 EU-005 RA3GJ 599 0532 ------
QSO: 7017 CW 2010-07-25 0945 M1KTA 599 0108 EU-005 DK3KD 599 0418 ------
QSO: 7002 CW 2010-07-25 0947 M1KTA 599 0109 EU-005 GI0RQK 599 1186 EU-115
QSO: 7104 PH 2010-07-25 0952 M1KTA 59 0110 EU-005 GM0ADX 59 1327 EU-008
QSO: 14192 PH 2010-07-25 1015 M1KTA 59 0111 EU-005 IQ3MO/IL3 59 1138 EU-130
QSO: 14196 PH 2010-07-25 1017 M1KTA 59 0112 EU-005 DJ6QT 59 0478 ------
QSO: 14210 PH 2010-07-25 1022 M1KTA 59 0113 EU-005 SN3S 59 1158 ------
QSO: 14226 PH 2010-07-25 1023 M1KTA 59 0114 EU-005 E74AA 59 0178 ------
QSO: 14249 PH 2010-07-25 1026 M1KTA 59 0115 EU-005 OL5T 59 0821 ------
QSO: 14250 PH 2010-07-25 1027 M1KTA 59 0116 EU-005 IZ2FOS 59 0876 ------
QSO: 14280 PH 2010-07-25 1037 M1KTA 59 0117 EU-005 DL1KZA 59 2313 EU-057
QSO: 14300 PH 2010-07-25 1041 M1KTA 59 0118 EU-005 CS2K 59 2225 EU-167
QSO: 14297 PH 2010-07-25 1042 M1KTA 59 0119 EU-005 SP9LJD 59 1729 ------
QSO: 14269 PH 2010-07-25 1044 M1KTA 59 0120 EU-005 VC9A 59 1577 NA-014
QSO: 14256 PH 2010-07-25 1048 M1KTA 59 0121 EU-005 UU9CW 59 0962 ------
QSO: 14201 PH 2010-07-25 1107 M1KTA 59 0122 EU-005 IL3T 59 1243 EU-131
QSO: 14204 PH 2010-07-25 1109 M1KTA 59 0123 EU-005 IQ2CJ 59 1594 ------
QSO: 14167 PH 2010-07-25 1114 M1KTA 59 0124 EU-005 SK7OA 59 1071 EU-067
QSO: 14164 PH 2010-07-25 1118 M1KTA 59 0125 EU-005 SP1QXK 59 0322 EU-132
QSO: 14136 PH 2010-07-25 1119 M1KTA 59 0126 EU-005 RN3AW 59 0216 ------
QSO: 7113 PH 2010-07-25 1124 M1KTA 59 0127 EU-005 DK0AE 59 0130 ------
QSO: 7109 PH 2010-07-25 1125 M1KTA 59 0128 EU-005 MM0GPZ/P 59 0508 EU-123
QSO: 7105 PH 2010-07-25 1127 M1KTA 59 0129 EU-005 MI3OZX 59 0001 EU-115
QSO: 7105 PH 2010-07-25 1130 M1KTA 59 0130 EU-005 EI8JB 59 0102 EU-115
QSO: 7136 PH 2010-07-25 1135 M1KTA 59 0131 EU-005 DN4MH 59 0175 ------
QSO: 14275 PH 2010-07-25 1150 M1KTA 59 0132 EU-005 7S2S 59 1008 EU-139
QSO: 14278 PH 2010-07-25 1151 M1KTA 59 0133 EU-005 OK1Q 59 0447 ------
END-OF-LOG:

New shack

2011-07-13T10:39:00.000+01:00

Started on a new shack and here are photos of it.

Homebrew DSO

2011-05-18T12:02:00.002+01:00

The image is from an engineering version of the product, not released yet.

Having spent a fair amount of time recently learning some FPGA programming I'm going to have a go at building a homebrew version of this DSO for my own learning purposes. The product they call DSO-203 which is a quad channel portable DSO.

You can find some of the information here http://www.seeedstudio.com/forum/viewforum.php?f=22 Hint: try chrome or google translate :-)

They have used an FPGA that is not readily available through my 'normal vendors' but it is available and it is a low power portable device and as the FPGA source is available it sort of makes sense.

The front end uses AD9822 8 bit AD so the resolution is 4096 bits, there is a 10 bit version available so might investigate that too. the band width is claimed at 36MHz which looks reasonable.

The reason why I looked is I am in Cambridge and so are ARM and just over a mile away and I picked up a flyer recently about ARM chips and thought I would have a bash at something bit more complex.

No idea how long this might take but the SMT pad layout is available as are some decent high resolution images as well as the schematic so this might be a fun hardware build.

From http://www.seeedstudio.com/forum/viewtopic.php?f=22&t=1929 the circuit diagram:

You'll also find the source and other useful items:

https://github.com/Seeed-Studio/DSOQuad_SourceCode

This is the sort of thing it produces

Turn a soldering station into a reflow tool, using an old aquarium pump and length of silicon tube a bit of wire wool.

2011-03-31T09:07:00.000+01:00

I have just replaced my old soldering iron (Maplins N78AR
(http://www.maplin.co.uk/module.aspx?moduleno=35016) solder station) it is 50W
so great for big PL259 connections and making PCB enclosures, has a grounded tip
and it does have spare precision tips too... they have it on special promo right
now for £14.99 which was half what I paid originally. I find the 1mm fine tips
are fine for SMD work.

Anyway the old one the element gave in after 5 years use so I thought try to see if
I can use the old one as a reflow soldering iron instead with a little home-brew effort.

To confirm the element had gone I had dismantled
the old one and I saw that the element and another old iron (Weller maybe?) are
hollow and almost identical construction wise, I have an old fish tank air pump
and just out of curiosity fed some blue high temp silicon tubing (so will not
melt) into the handle base and into the base of the heating element tube. Air
passes up through the tube where it is warmed on the way to the tip which is not
there now just a 5mm diameter hole. The air flow can be controlled with a simple
pinch on the tube with a thumb screw.

I tried this for real and it sort of works, old PC motherboard components reflow
quite easily once set to about 75-80% on the control and adjusting the air.
Adding a little extra wire wool at the tip of the tube seemed to help with the heat
and the dimmer control (basically just a current control) adjusted the air temp.
You turn on the iron, get it to temp and then turn on the air and adjust until
flow/temp is right. The wire wool smoked a very little initially but is fine now, whole thing
almost silent apart for a little hiss and the pump buzz.

Seem to have an extra tool for SMD.

Anyone else done this?

Will post some pics soon.

Wobbulator & High gain RF probe

2011-03-28T09:18:00.000+01:00

From a Radio Bygones project by Raymond Haig whole 2003 issue can be seen hereI have started to build the wobbulator that I'll use to align the R1155 (probably best known as the RX set in WWII Lancaster) I was given last autumn. Also the partner powered RF probe.

I had a bit of trouble trying to find 400V DC 0.1uF polyester caps (loads at 250V or 285V and a couple at 3KV! I will use .22uF 400VDC ones for now.

The box is still available from Maplin and I have everything else in the 'junk box'. Dave, G4EBT sent me a pair of PCB a while back (hope I did send him a cheque) and I just printed out and laminated the front and will attach to the box lid.

Jabdog came up with the varicap diode and the toko coils and I had everything else.

Will post some pictures..

Back up and running again, apologies been away for a bit.

2011-03-16T13:12:00.001Z

After not been able to do anything radio for a while I'm back up and running again.

Last w/e I put in an entry to the BERU contest (Google for RSGB BERU) using a very limited setup. I now commute on the train to work, about 90 mins each way, so finding time to do some research on the latest projects. Lots of QEX issues unopened!

Bit of a backlog of things that need to melt solder on but should have those out of the way soo and then will be ready for a new shack in May.

Thinking about an island trip for RSGB IOTA in July 2011 so if anyone has any suggestions all ears.

changing jobs and country so nothing posted for a bit.

2011-03-04T15:18:00.001Z

Once dust settles and get things unpackaged again will be back melting solder on a few things.

Got the SDR Cube and NuePSk modem to build, there are a couple of FPGA SDR projects I'll be starting on too.

QRP2004 Control Board - ExpressPCB Version -UPDATE

2011-01-23T12:23:00.000Z

Project group ok'd it so I'll add ExpressPCB layouts for the PCB on the yahoo group as I create them. Please be warned check them before you use them and needless to say if you see an issue please advise.

There are no .sch just the .pcb files

http://groups.yahoo.com/group/qrp2004/files/ExpressPCB%20Layouts/

QRP2004 Control Board - ExpressPCB Version

2011-01-17T20:59:00.005Z

I was asked if an electronic version of the PCB masks exist for the project. They don't and as I like using it I have started to create Express PCB versions of the PCB. This is the control board. Note I have used the NARROW SOIC-16 version of the MAX232/ST232 SMD I will also consider the normal DIL version too.

The layout are sized exactly the same as the originals and generally will follow the original layouts, right now no bottom layer tracks exist on this image on the blog.

I'll work through all the boards and possibly build up an alternative making a few additions, I may produce a layout using SMD components where possible for many of the discrete components especially the R and C.

Note I do not create the .sch files just the .pcb files.

I'll wait to hear from the project group if they mind these being shared.

Same as above in poor French:
Le même que ci-dessus en français pauvres. Apologie de langue maternelle française.

On m'a demandé si une version électronique des masques PCB existent pour le projet. Ils ne sont pas et que je veux l'utiliser, j'ai commencé à créer des versions Express PCB de la carte. C'est le tableau de commande. Remarque, j'ai utilisé le ETROIT SOIC-16 version de la MAX232/ST232 SMD Je vais également examiner la version DIL normal aussi.
La mise en page sont exactement les mêmes dimensions que les originaux et en général suivront la mise en page originale, à l'heure actuelle aucune piste couche de fond existent sur cette image sur le blog.
Je vais travailler par tous les conseils et peut-être constituer une alternative faire quelques ajouts, je peux réaliser une maquette en utilisant des composants SMD, si possible pour de nombreux composants discrets en particulier la R et C.
Note Je ne crée pas les fichiers sch. Seulement les fichiers de pcb..
Je vais attendre d'entendre le groupe de projet si elles l'esprit ces partagé.

QRP2004 Control Board - Day 2

2011-01-16T17:09:00.002Z

The prepared Control PCB is fitted with all the IDC sockets and wire links including all the wire links through the board so the ground plane is connected both sides. In the above photograph you can see I have prepaced some of the components before continuing. On the reverse side there are just two wire links, 5 2K2 SMD resisors and the ST232 SOP SMD IC. Note if you are going to use the project group PCB masks you need to use the ST232CWR WIDE body version.

I am building from one of the component sets I previously put together, I printed off a copy of the yahoo group spreadsheet to mark off the components. I have a number of bags that I have presorted the components into according to the boards.

The LCD connections to the Control Board I have used a SIL connection strip and it is connected to the LCD by a length of ribbon cable. The 7805 regulator will need mounting hardware as well.

QRP2004 Build

2011-01-05T10:00:00.004Z

PLL photos with the tiny AD9835 tracks.

Note the laser was on draft 300dpi hence the slight dotty nature of the tracks I have done this as I wanted to test out the process.

Tinning will cover these. This was after just 15 minutes in tin solution.

Just to see how low you can go...this is what you get at 150 dpi printing:

I might b tempted to chase a blob of solder about these pads/tracks

QRP2004 Build day 1 PHOTOS

2011-01-05T09:17:00.001Z

Series of photos as the boards are made up.

First clean all the boards

Then iron on the film (audio board as example)

The peel off the film (control board as example)

All the boards then same again bit touched up.

As they come out of the etch, note I use red electrical tape on the reverse
ground plane.
The resist layer cleaned off.

Pair of boards about to be etched
A simple Sodium Persulphate etch bath (note the blue colour is from the copper
in solution)

QRP2004 Build day 1

2010-12-31T11:57:00.001Z

Here starts the log for the build today easy first day.

I'm creating the PCB and my process is to use press and peel film (Maplin AB15R) so I use the REVERSED images of the CU layer you can obtain either from the qrp2004 project team website (http://myweb.tiscali.co.uk/qrp2004/) or the yahoo group (http://groups.yahoo.com/group/qrp2004/files/) Printer is a laser doesn't work with an inkjet printer, Samsung ML-2240 and I am printing 1200x1200 dpi and as DARK as I can get it.
Make sure you check the print size is right. I used a 40pin DIL socket and couple 8 pin DIL sockets to check the sizes. Mine I had to print at 107% size. Print to normal paper until you get the size right.

Anyway I have 7 nice pieces of blue film ready to use.

It is still cold out so doing the rest of this in doors.... (except the etching)

1. Cut out 7 pieces of PCB sized to fit. Mine are slightly oversized.
2. Clean them of all grease and finger prints (I use Acetone and then fine wire wool and emery paper in a circular pattern). You end up with 7 shinny pieces of PCB. Now clean all the wire wool or emery paper remnants away
3. Iron on or feed the sheets and PCB through a laminator (I will be testing the later option on another build).
4. Allow to cool, peel off the film.
5. I use black marker (permanent) on the top ground plane side, you can use close fitting tape etc... your choice.

Outside now in shack...

6. Etch. You do not need a tank but I home-brewed one from a fish tank heater and aerator pump. I use either Ferric Chloride or some clear etchant. The home-brew tank I set the solution to 35degrees C and let it bubble away for about 35 mins and the boards are usually fine. Wash the boards with water and allow to dry.
7. You have a choice: either remove the etch resist pattern off the boards now or wait until after drilling the boards. I will tin mine (you do not need to) so will remove the etch resist and the tape or pen from the other side and I use a dip solution, you can tin too by chasing a bead of solder around the board (hint this is much easier when NOT drilled!). If not tinning and if you remove the resist the copper will tarnish quickly so you might want to use a flux spray like KS10.

Now the boring bit... drilling c900 holes! This might take a while.
I use a Dremel in a stand (the task is hopeless if not in a stand) with 0.7mm drill bit. Note some holes will need to be enlarged will cover those in later posts.
Drill all the 3mm holes for the mounting and the other 4-5mm holes for the TO220 and other transistors.

I think the drilling holes is why so many home-brewers have moved over to SMD...

I'll post some photos later.

You can use a photo resist and print the CU layer images to sheets and expose and develop etc... but I have not done it that way but many other homebrewers do.

How to make a CW QSO

2010-12-30T11:18:00.003Z

The original site at http://zs6ez.za.org/tutorial/cw-qso.htm has disappeared so I post that page here for reference for those trying to get started in CW.

A search for zs6ez on QRZ:
Born 1964, licenced 1980 as ZS6BCR. I've basically been inactive since 2000, due to other commitments. I hope to resume some ham radio one day. My main interest was in contesting, where I held several world and continental records in the single band category of CW, RTTY and Phone contests. I attended WRTC three times, as W6O, OJ1W and S572L. I ran a series of DXpeditions in the Eighties and Nineties, emphasising low band, WARC band and RTTY activity. You may have worked me from 7P, 3DA, A2, IH9, V5, ZS0 or ZS9. I also once did a bit of DXing, with 10BDXCC, 5BWAZ, 5BWAS and Top of the DXCC Honor Roll. I've slipped down a bit with the most recent additions, but maybe I'll get up there again one day. In the mean time, I'm working on my DXFC score (see http://dxfc.org) while flying business jets as a South African Air Force volunteer, playing with my daughter, holding down a real job, working on my PhD, managing a small group in our local church and running a flying school.

How to make a Morse Code contact...

The original is back up on a new site, here is email from Chris about it.
----- Original Message ----
> From: Chris R. Burger ZS6EZ <chris@********>
> To: Dominic Baines <dombaines@********>
> Sent: Fri, 31 December, 2010 1:02:57
> Subject: Re: Fw: [GQRP] Re: OT? Morse procedures...
>
> > Other emails used all bounced...
> To this address，or did you use an obsolete address？ I'm not aware of a
> problem with this address。
>
> > Please let me know if this is a problem.
> I would prefer if you linked to the actual article：
>
http://zs6ez.org.za/tutorial/cw-qso.htm
>
> That way，if I make changes they will show up。Also，Google is more likely
> to pick up the new address if you link to it。
>
> The original domain name disappeared，so I suddenly had to establish a new
> one。 All the original content is there。
>
> Regards
>
> Chris

http://m1ktaipodamateurradio.blogspot.com/

2010-12-22T15:00:00.002Z

Started something new today
http://m1ktaipodamateurradio.blogspot.com/

QRP2004 Build

2010-12-14T06:29:00.005Z

I have had a few questions about this project ( http://groups.yahoo.com/group/qrp2004/ for details) so I will start a build from scratch and blog it here starting in the new year (i.e. 2011).

This is the designed polyphase network for the QRP2004

Copyright © 2004 - 2005 by QRP2004 Design Team

The project design team include details of the design and method where you can look at options using different components (depending on what you have to hand), using different components the results are:
(RED) C=33nF, R (Kohm) 12,10,6.8,3.9,2.7,1.8,1
(BLUE) C=10nF R (Kohm) 47,33,22,15,10,6.8,5.6

See the project docs for details.

QRP2004 Web Site: http://myweb.tiscali.co.uk/qrp2004/

Mag Loop

2010-12-05T11:20:00.007Z

Just posting this as not QRT.

The WX here in Mechelen (Belgium) had been snowing for the last week. So I have taken a mag loop antenna built by Clive (M5CHH) (from G4TPH design) I have put it up suspended in the open door way out to the patio.

I determined that the door was 100% uPVC not metal framed and there does not appear to be any chnage in coupling with the door closed or open. The sealed windows are some metal looking but doesn't seem to effect the loop.

Just thought you might like to see these:

This is the loop on 40m :-)

This is the loop on 30m :-)

This is the loop on 20m :-)

I am about to go out to find a place were I can get some AA batteries for The 30m QRSS beacon I obtained from Han (G0UPL) and Steve (G0XAR). So hopefully ON/M1KTA should be QRV on 30m shortly.

The land lord still will not allow an external antenna so this looks like a good option.

BTW the pictures grabbed from MiniVNA Java software. Putting it on a contunous loop makes tuning dead easy.

Not tried a different balun that will give me 10m yet. I used 10 x 400mm legs to make up the loop. I'll post a photo soon.

I'll run it with the FT817 later.

Quick and cheap dummy load for QRSS/QRP TX

2010-10-30T08:47:00.006+01:00

In Belgium and don't have the rest of the homebrew shack with me but needed a dummy load and ability to measure the RF levels so knocked this one together.

I grabbed a tiny strip of veroboard and 20 1k 1/4 resistors, 15nF capacitor and a 1N5711 diode.

It is 2 sets of 10 x 1K resistors in parallel so 50 ohms. The diode and capacitor follow the dummy load so can use a cheap typical DVM to measure the RF voltage.

The 1N5711 limits the power to about 15W but the resistors would frankly pop well before then.

The circuit is not original, neither is the idea and I do not claim any ownership in any way.... I built the excellent NorCal SMT dumy load a while back.

The basic design can use larger wattage resistors but if you want to do this for something that might last a while then ideally you use identical resistors. This would mean 2 x 100, 4 x 200 etc... A cheap 10Wdummy load is 44 x 2K2 resistors.

Back at QTH I have 4 x 200ohm 25W chip resistors in TO220 packages bolted to a heatsink using insulated TO220 washers and a little heat sink paste. There are others that use these suspended in mineral or olive oil for QRO use (check out http://www.hanssummers.com/dummy.html) . I planned to bolt an old CPU fan to the heatsink to increase run time but mine never gets that hot.

QRSS HB Build

2010-10-11T18:44:00.003+01:00

Was sent this image of a QRSS homebrew build.
I then did a double take... it's from ET "Phone Home"

:-)

QRPLABS QRSS kit

2010-10-11T17:03:00.002+01:00

just melted solder on this

Another K1 Build - this one will be mine this time.

2010-09-14T06:40:00.004+01:00

Various shots going through the RF Part I build.

The Front panel and filter board already built.

The extensive home brew bench.

FtTuthill80 Build

2010-09-12T20:16:00.004+01:00

Kits components as sent.

Following the pdf instructions of Dan Tayloe, N7VE

These are the build images from the kit I just started to build.
Up to the power test (used a 9V battery) and the blue LED lighting.

Blue LED

Diodes

Sorting the 0.1uF caps

0.1uF caps

More caps

And more

Electrolytics

Resistors

More resistors

Applying 9V.

The LED lights blue.

Elecraft T1

2010-09-12T15:04:00.014+01:00

Was recently given an Elecraft T1 auto tuner kit and as now working in Belgium thought I'd make it up. First started in hotel room.

The portable 'homebrew' bench is perfectly adequate. Note I have brought a 12" square of PCB to build on.

Initial components going in.

Relays fitted.

Fitted the underside capacitor.

Fitted the sockets and headers.

Built up the control interface.

First fitting. Looks good so far however, visual check of all the components against the build list and couldn't work out why had extra FT37-43 torroid. Then remembered there is an errata...

Oops... errata clearly state use 2 FT37-43 cores for T2 not 1.

No harm done, removed T2 and added the new T2 fitted easily.

Removed the PIC, added battery, checked the voltage through the 2N3906 when tune/pwr switch depressed and onto the regulator says 6V.

Added PIC and tested the power on, seems to be fine. Will test again once have working TX with me in Belgium.

dBm Meters using the AD8307 logarithic amplifier

2010-08-05T09:51:00.002+01:00

I'm having a go at building a couple of dBm RF Power Meter from AD8307

The first is W7ZOI design having found a nice 500uA meter at w/e there is a nice construction website here. Also note W&ZOI own notes on callibration here. There are plenty of variations on this design and the daa sheet and application notes from Analogue Devces are worth a read. Some like this one use an AF amp to provide an audible feedback too

Part of the circuit from the design from N2PON (QST August 2008) uses temperature compensation. Basically he divides the pin 4 output of the AD8307 that is fed to a DVM through a resistor network containing a 10K pot that adjusts the GAIN to achive c1mV/dB with an NTC temperature compensating thermistor (c1K at 25'C) connected to ground so if there is any temperature changes the instrument retains a level of thermal callibration.

In many places this is not necessary but I know from experience my own shack does vary from -10'C in deep winter to +30'C in summer if it is unheated. Any meter is likely to be built into a die-cast box that will take a while to equilibrate too... so I am trying to use a thermistor salvaged from a PC motherboard (as had a few) with a 2k7 value at 25'C and c4K close to freezing and 500ohms when about 100'C (basically put it in boiling water and into ice water and measured). So I think could use it but would adjust the value of by placing resistors in parallel and series with to obtain 1K at 25'C.

Just back from Rhine trip

2010-07-23T13:38:00.002+01:00

Some interesting post whilst away...

Seems I came 2nd in IOTA qrp category in EU005 during 2009 as I have a certificate!

Lots of QSl cards some go back as far as 2006, lots more 3B8/M1KTA.

An FPGA development board.

Anyway I'll be preping for the RSGB IOTA contest later and making a 12 our entry again then back to melting solder on the MOBO builds.

MOBO V4.3.4 SR V6.3 (Original) preparation

2010-06-14T18:03:00.005+01:00

I just build a new SR V6.3 from scratch and added the headers for RX and TX IQ and beefed up the power.
I didn't have a 1N5422 but I have a 1N5408 instead and after a quick test then extended the diode PCB pads a little so not as 'tidy' as the little DO41 drop in replacement.

I did a scratch rebuild as the previous build had a LDVS version not a CMOS Si570 in place as a sample chip and could go to >260MHz and as this is for SDR-Radio development I will keep the build to 'vanilla' only.

I noted the MOBO kit seems to have plenty of jumper connectors so will make some up.

I will use a length of RG174 or similar for the RF and I will use some shielded audio cables for the RX & TX IQ.

MOBO V4.3.4 POWER SWR Head

2010-06-13T19:17:00.003+01:00

Images of the build.

I used a length of RG58 as the single turns through the binocular core.

I will also homebrew one of these using 1N5711 and discrete components.

MOBO V4.3.4 Mini Filter A Set

2010-06-13T19:16:00.003+01:00

PCB made up and installed.

Quick test on a VNA shows the filters frequencies are about right.

MOBO V4.3.4 PA

2010-06-13T11:56:00.003+01:00

Mounting that heatsink.

I did this:

MOSFET attaches to REAR.

I used a needle file and removed the anodising on the bottom ends of the heatsink and around the TO220 middle mounting hole.

To attach th heatsink to the PCB I used two self threading M3 (ish) screws that bit into the heatsinks and created a good contact (I checked resistance was <0.1ohms). Turned the board up away from you on the right hand side (R30) underneath I used a flat washer and a Computer red insulating washer, on the left hand side I used a flat washer and a star washer that bit into the tinned area. In between the heatsink and the top of the PCB on both sides I placed a star washer.

I secured the heatsink to the PCB first THEN and Only after it was secure did I attach the MOSFET and then checked for conductivity between the ground tab on the MOSFET and GND on he PCB. Once satisfied it was good I soldered the MOSFET into place.

The Heatsink sits about 1/32" off the PCB and it and all mounting hardware is clear of any components..

NB on the (outer edge of PCB) of the TO220 mount I used a brass washer and heat sink compound between the MOSFET and the heatsink, The screw was brass M3. On the reserve side (facing into the PCB) no heat sink compound and I used a star washer and flat brass washer to make a good contact between the MOSFET and the heatsink.

MOBO V4.3.4 Build for SDR-Radio Support

2010-06-12T19:22:00.002+01:00

Asked where I am with this so here are the latest images.

About to add the PA.

Then will build the Mini Filters (Set A).

I have a Blue and White 4x20 LCD and a 36 pulse rotary controller. I have a 128 coming from US but not here yet.

Once all together will test and align... then it will be ready for Simon.

Summer 2010 Trip

2010-06-11T09:39:00.002+01:00

I'll keep this separate from the main home brew blog.

http://m1ktarheinradweg2010.blogspot.com/

MOBO AVR

2010-06-09T20:17:00.002+01:00

Build images

R1155L New acquisition

2010-06-05T11:24:00.002+01:00

Initial photos.

IF/AF Strip

2010-06-04T18:00:00.012+01:00

I have been building a few things lately all using a 612/xtal/612/lm386 IF/AF strip so I made a PCB layout for it as I ran out of manhatten pads and the expresspcb software was easy to use. I just reworked it and this was done using Wine under Mint Linux (see W8DIZ latest series of QQ articles). If you really need it ask and I can send you the .pcb file, but I never drew designed or made a schematic file and I tend to use pretty wide tracks and spacings as much of the use is with older salvaged components and I found it easier to solder some things that way.

I have made using single and double sided PCB with blue press n peel film I don't actually send off to Express PCB to make them up.

The layout is for variable band width xtal filter using diodes as variable capacitors (no identification on the layout) but you could omit them and the resistors and an external pot/voltage control and just use fixed value caps instead. I have used MV209, MVAM109 varicaps, 330pf and 560pf caps for the filter. I seem to use 100pF or 220pf for the xtal filter in/out. Xtals are cheap HC49 types I have bags of and I sort of match them crudely (colpitts oscillator) including the BFO. If don't want to use 4 crystals just bridge the ones you do not want to use. Note the BFO one of the capacitors is a trimmer (don't have a component for it sbut I know for me a normal cap pin out works. The L on one leg of the BFO crytsal can be removed, it allows it to be pulled a bit.

The L on the input can be bridged.

I have included dual voltage regulators providing 8V and 6V from a typical 12V source but a 9V source will do just as well. In that case apply 9V to the 12V location, omit the first regulator (right of 12V in) and the electrolytic but use the regulator upper hole and place a 0.047uF or 0.1uF in it to (ground) centre regulator pin hole. I made up with TO220 but the holes also suit TO92 as well (check the component layout for the TO92!).

After fun and games with a QRP ARCI 72 part challenge entry I never managed to submit in the end I altered the PCB and it now includes RX mute using almost any FET (2n7000, BS170 are what I use) across the LM386 input (watch the FET pins, G goes to the RX mute, S to pin 2 D to pin 3 of the 602/612! Note that the component layout does not match the body of all FET). The 6V RX signal activates a simple NPN transistor (2N2222A, 2N4124 almost anything with Hfe about 150-300 seems to work) to apply a couple dB amplification to the RX signal. I can 'see' a signal on an oscilloscope at about 0.25uV without the transistor and c0.17uV with it.

Any SA612/SA602/NE602 et al can be used all pins are the same. The electrolytics are all 100uF 16V and might not be optimal for every situation, the R and C values I change and suit what I am building. Check your circuit and sure it will provide the values that will work. I do not provide what I have used.

The LM386 I added no volume control as I control volume on the speaker/headphones. Usually you would do this on the input to the LM386 but I grabbed the idea of this from the K1 which does this and uses a pot of the output into an LM380. This set up works for me.

The LO input can be almost anything, xtal, VFO, VXO, PTO or DDS as long as the signal is large enough and it is buffered (J310 FET is ideal) I use anything from a 100pf to a 1000pf cap between the LO and the 602/612.

Obviously all filtering of harmonics of the LO and the RF input need to be handled external to the PCB and I use twin TOKO can (3333,3334,3335) or T37-6 BPF (see GQRP for examples) on the RF input.

K1 build.

2010-06-02T20:31:00.008+01:00

Just finished.

K1 build.

2010-05-28T09:28:00.006+01:00

40m Pre-Mix Oscillator Signal Spectrum and Plot
Pin 4 J6 Filter board

20m Pre-Mix Oscillator Signal Spectrum and Plot
Pin 4 J6 Filter board

Adjust the pre-mix filter using an oscilloscope and pin 6 on J6 filter board.
(nice thing is same pin both bands) You realy need 4 hands to video this so apologies poor video.

A signal at last!

PIC-A-STAR group photo

2010-05-25T10:27:00.005+01:00

Made it to a group photo and chat this year.

http://www.radio-kits.co.uk/pic_a_star/photos/index.htm

I'm the tall one in the middle of the May 2010 - Luton car boot sale (Dunstable Downs Rally) photo.

K1 build RF part II

2010-05-22T20:03:00.003+01:00

90% of TX side done now, just got the PA transistors and the transformers to solder in (just in place mechanically for now) and then that should be it as far as melting solder is concerned. There was one missing 473 (0.047uF) cap (C50) I have substituted in something from my own supplies that should work until Elecraft send a replacement.

The alignment for RX doesn't always seem to work for TX and the manual and notes say that the K1 uses the same filters for RX and TX and the uPC in it does a calculation and the ALC sets output power to less than 0.1watts

Anyway should be done soon. I am off to the Dunstable Downs rally tomorrow. Hope to be able to finish the build over the bank holiday.

K1 build. Up to RF board Part I

2010-05-22T16:26:00.002+01:00

Just finished the build of the K1 up to the end of the RF Board Part 1.

Short video of the finished article.

The current draw with the back light is 64mA.

RX side all done and aligned. I used three signal sources, an FT817, a USB Si570 and a Colpitts Crystal oscillator using 2N3904 and 7.040MHz and 14.060 MHz so should be pretty true but the frequency can be amended through the menus. But once amended for 40m automatically the signal frequency for 20m was correct.

I have done the alignment with a side tone at 600Hz feeding the signals into a PC and used adjusted with an audio scope, built with stereo audio and the side tone is working fine and both hand and paddle key work fine. I have left keyer at 16wpm for now.

I might have to adjust the menu for S meter readings that suit later as I have left the level at L50 which is the default. I was listening to a cw contest and some of the local stations were definitely S9 and appeared so but the weaker ones did not seem to move the S meter. AGC is audio derived so an s9+40 signal causes a 'blip' and the AGC attacks hard the AGC decays pretty slowly. Turn it off and no S meter.

About to get the TX side started.

SR V6.3 build

2010-05-19T10:27:00.001+01:00

I found this an interesting read.

http://sdrbuzz.com/forum/showthread.php?t=73

SDR list

2010-05-10T14:06:00.001+01:00

For those wanting to see a pretty comprehensive list of SDR options as they stand today then this link is seriously worth following:
http://f4dan.free.fr/sdr_eng.html

ARCI 72 part challange - realised error

2010-05-07T09:12:00.001+01:00

Morning after... over the shreddies and visual check I realised as I had swapped FET from BS170 to 2N7000 having run out of one TO92 version (see http://www.jaycar.com.au/images_uploaded/2N7000.PDF for the two TO92 pin configurations) obvious error... I had connected one of the FET switches for mute backwards at the LPF input (shared with RX as forms half the BPF), anyway on TX instead of the FET passing RF to the LPF instead I was feeding the RF directly into the RX chain (abt 4W). Oops! I hit the key for a second and seeing no RF out and a brief squeak/squeal from AF stopped and heard no RX afterwards. Damage done but no magic smoke!. The IRF510 PA still seems to work so I have a TX :-) anyway might explain why it doesn't work ho hum! The 8 pin DIL PIC 16F629 (like old 509) was hosed as a result as the switch before the AF stage sent the RF into the PIC pin instead!

Normally a sensible builder would have reverse diodes etc in line and plenty of decoupling caps, voltage regulator, used npn transistor to switch the FET's and added an extra stage on the LPF as only 30dB down but omitted all this stuff to manage the part count! I realised I could have saved 3 as didn't need the xtal filter input transformer and couple caps used to decouple DC I had doubled up in two places (BFO and VFO into mixers).

Had this been a DC RX then 72 parts easy.... still learnt I could build a half decent <600Hz IF filter with two crystals not 4 or 5 :-)

Going to be interesting to see how the others actually managed it.

ARCI QRP 72 part challange - Going to miss it.

2010-05-06T20:59:00.005+01:00

I am trying to get the project rebuilt/boxed after reworking the PTO. Unfortunately tonight after 3 hours trying I cannot get the cw RX/TX mute to function as it did and the TX has some nasty spurs so I've bust it somehow, and as not boxed up yet got to face reality I am not going to make the deadline to get this to FDIM so will not be entering. It is my own fault I mixed the Dayton and Friedrichshafen dates up so lost 5 weeks. Frustrated, angry and embarrassed all in one...

My one IC wasn't anywhere in the RF part I used PIC keyer that also controlled the RX mute (FET on the AF).

Anyway, when the w/e is over I'll write it up.

My final part counts were:

TX
13
Basically a VXO FET oscillator using an IRF510 followed buy a 3 pole LPF. Some pulling possible using a small trimmer cap. Built for 80m.

RX
57
BPF, that shared the TX LPF, FET mute of the front end and the AF section. DBM mixer, M5 Brass bolt PTO, 2 8MHz crystal c580Hz filter, 8MHz BFO (J310), RF amp/product detector (J310), AF amp (3 NPN).

PIC
2
PIC + one resistor. I would have added a side tone too but needed one more component!

72 total.

The whole lot could do with a bit more decoupling and as planned on battery use no main voltage regulation except one zener in PTO. I build every module on a separate PCB, manhatten/ugly style.

What SDR kits are out there?

2010-05-04T08:46:00.009+01:00

I was asked this at a rally demo recently:

>> I was talking to you at the Loch Erne (Enniskillen)Rally on the 11th April past.
I would like to know:
What SDR kits are out there to build
What would you recommend to start with and which one to work up too.
Where can I get them from and how much are they ?

> Any thing else that you think that I may need to know about kits and what software to use would be great.

The answer is going to take a while to formulate with all the information but this post will be a place holder for it.

I will fill out the sections below.

The initial starting places to look for information on building SDR kits could be:

http://www.wb5rvz.com/sdr/ Robby has written extensive notes on the construction of all sorts of SDR kits.

http://www.kb9yig.com is Tony Parks website he is 'Mr Softrock SDR' as the kits are his. You can order directly from him but there can be some delays as he does the kitting personally.

There is an Elecktor SDR project, don't know much about it.

The Genesis SDR project is a bit more advanced that a softrock and for those who do not like surface mount the projects are good. http://www.genesisradio.com.au/

I have a kit in the design phase.

There are plenty of others out there I just either don't know them or haven't mentioned them,

All these so far use the concept of a PC sound card and software to decode the signals and the bandwidth is between 48khZ and 192kHz which is fine for most uses.

Expect to pay anything from £20 - £200 for an SDR kit. Any SDR TX options should NOT be considered by a beginner unless you have the RX side working first.

No matter what the RF hardware you need to run software for SDR. Don't expect to run it on that old 386DX DOS based system you use for VHF logging It will not work. You will need a good sound card and any reasonably modern PC should do well. The larger the monitor and the higher resolotion the easier you will find 'looking' for the signals. I use in shack an old Pentium 3GHz laptop or a Dual Core AMD 2.8GHZ laptop, 24bit 96kHz external USB sound card and twin 17" monitors. All together would cost less than an FT940 would. I do demos at rallies with an ASUS eeePC 4G which cost me £125 from Toy'r'us and the sound card in it is brilliant 24 bit and 96khz no problem and a 17" monitor.

Another option that Pat Hawker G3VA talked about maybe 10 or more years ago is to use direct digital conversion and digital up conversion to sample and convert RF directly to data and visa versa... the constructions are not really for anyone but the seriously experienced and surface mount components rule the day, go to http://openhpsdr.org/ and you will find some more details. They use FPGA chips to do most of the digital signal processing. Some of the newest FGPA chips have huge capabilities but cost £10K (HPSDR doesn't use the expensive end ones!) and those are what the military and broadcast radio and TV use.

Non kit options:

RFSpace: SDR-IQ, SDR IP, SDR-14

Flex Radio don't know much about them... very expensive!

Software:

Lots of options but a major one anyone has to make is are you going to try to run SDR with Linux or Windows.

Loads say they want Linux as it is open source and all that but and I make zero excuses for saying this but 99.99% of them never code a damned thing and much of what they say is hot air. The choice is really down to what you run your shack with, most use Windows and some of the more user friendly beginner software is Windows based. Not to say the Linux stuff isn't but it tends to be written for specific functionality not overall usablility.

No excuses for recommending it, as I am supporting Simon Brown HB9DRV (He wrote Ham Radio Deluxe) SDR-RADIO (http://www.sdr-radio.com) which he has now released v1.0 of. It doesn't have TX support and a few other things just yet but it will and if you know HDR and DM780 it will integrate with those nicely.

Other options are: (Again all Windows and no source code available)

ROCKY http://www.dxatlas.com/Rocky/

M0KGK http://www.m0kgk.co.uk/sdr/index.php

WinRAD http://www.winrad.org/

A homebrew siggen I would advise anyone to try to look at building to look at image rejection is this

... I'll add to this as time goes on....

ARCI QRP 72 part challange - Update

2010-05-03T16:23:00.014+01:00

Further to my tests ages ago with PTO... http://m1kta-qrp.blogspot.com/2010/01/pto-vfo.html

Here I am again with the same test rig but with a different construction technique. Again I post the information here incase others are interested in trying out a PTO.

I have fused a number of M5 nylon nuts together, super glued them and wound red electrical tape about them. Into this I can turn a M5 brass bolt. It is much more stable than the previous constructions. Anyway onto this I close wound about 45 turns (I didn't count them at this stage) of 28SWG enamelled wire.

Final construction of the coil and screw will involve moving this to the PCB and not being panel mounted. A second nylon bolt will hold the far end of the assembly 'true' with the brass bolt.

Then using the same setup as before I retested.

I can now get the PTO to operate between 4.673MHz and 4.3MHz which is perfect for an 8MHZ IF and 80m rig.

Anyway as this is a buffered PTO, needed a little lift in LO signal for the DBM but it added a couple more components to the count so will see how my rig turns out.

I'm not going to use any component that is not generally available and every one must be possible to obtain from the 'usual' suppliers.

Hope mine is going over to Dayton with a UK attendee.
My TX uses just 13 components, crystal controlled and there is about 4-5khz ability to shift frequency using two extra components. That was the easy bit.
My RX... I am still tweaking it a bit so the count is not up to date but overall I am inside 72.
The rig should have a keyer (so an AVR or PIC is my one IC!) but if I don't get the code finished, it won't.

Some images of various bits follow, it is my intention to build this manhatten/ugly style so no fancy PCB required.

The minimal component count crystal filter. "So how did I select the components to use"... no fancy calculus... I looked in the junk box and then through what 1% caps do I have > 300pf and found three 560pF, three 390pf and three 680pf. So I plugged for the 560pf and built this crystal filter.

Then just to check how it performed I used my trusty MiniVNA in transmission mode and took a look.

Nice sharp filter. Note I added the FT37-43 transformers after I measured it at c24ohms so used trial and error and made 12T:8T transformers so the input and output are both 50 ohms.
In this image the transmission appears to be down 20db (it isn't!)

The TX side is dead simple to keep the part count right down. I went for an IRF510 which adds some legs rather than a 2N3866 et al but this means /P use may be a little reduced.

The variable capacitor, series inductor and crystal are missing from this image but everything else is on the board. RF out is the white lead to left, key (basically short to ground) is the purple lead on right. The LPF is very simple just one half of a normal LPF to keep the part count down and I played about with values to get this to a reasonable level but seems to work, it is a single T50-2 and two 1000pf polystyrene caps as the oscillator is crystal controlled I did not see any spurs. I might grab an image of the spectrum plot and the LPF transmission graph and post them too.

Oh BTW don't copy the TX layout the above will not work, was an early version I took a photo of.

I went for a simple double balanced mixer. The two 0.1uF caps and 56 ohm resistor on bottom left is the AF output and they act as a RC filter. BFO in is top right, RF top left.

*** more to follow....

SDR/QRP talk at Cambridge and District ARC

2010-05-02T18:20:00.003+01:00

Just been asked to give a SDR/QRP talk at Cambridge and District ARC.
As I am working in Cambridge again I expect to be local again for a while so this looks possible. No idea about dates yet.

I suspect a talk/demo might be best.

I'll have some of the Softrocks built with me and a handful of other qrp kits and builds.

K1 Build

2010-05-02T18:14:00.002+01:00

Some photos here
http://m1kta.ham-radio-op.net/m1kta/builds/K1/

So I am an Elecraft builder what does that mean?

2010-04-25T12:18:00.004+01:00

I write this as asked a few questions about my name on the Elecraft UK builders list.... http://www.elecraft.com/k2_builders.htm

I don't get paid by them to build for anyone and I don't pay them to include me on the list.

Exchange with one amateur from UK and I am building his K1 right now:
> I hope you don't mind me asing... I wonder how much you charge for your services? I am just in the process of buying a K1-4 and unfortunately just do not have the ability to build kits anymore due to a disability just don’t have the feeling in my fingers anymore since an accident last year).

My response:
Don't mind at all.

Yes I do build some things for others including now being asked to build Elecraft kits. Right now shack is insulated (and now heated so maybe less vfo drift!) with power etc. I have an IQPro DDS near completion, a PIC-A-STAR and a 500KHz TX needs finished off. I have just finished a number of softrock SDR builds but I only tend to work on my own things couple hours at a time. I can push these to one side easily and focus on this. If not in a rush I should be able to complete it pretty quickly. One self imposed rule is I would not build for more than one at the same time.

Charges... I have never charged to build anything yet. I work in IT and my normal charge rate is way too much to make this a way of earning a living and as this is a hobby I am happy to help others as many helped me early on :-) If work takes me away from home I suspect will not take with me but we can discuss this if it happens.

I was recommended to offer to build things by Elecraft after some saw my GQRP kit build display last year at Rishworth of BTX-20, PFR-3, MKARS80, HB-1A, numerous SMT Softrock SDR builds, an N2PK VNA and ATS-3 (6 band 100% SMT build and fits in an altoid tin!). Anyway I was asked if I would build for others and as I built a K1 a while back thought why not. I bought the K1 as a part build from a rally, thought it was SSB too initially as miss labeled and I sold it at another rally on a bring and buy stall as my CW wasn't/ still isn't that good and I was not using it. I don't have any contact with who bought it though.

No charge to build but you'd have to buy the kit and send it to me and cover the costs of the kit and postage to me and back. Buying from US if sent direct to me I 100% expect there will be some customs charge of one sort or another. But how about helping with things I'd maybe use to build it:

As this is through hole the irons I'd use are 18W Antex and a temperature controlled iron also from Maplin so suggestions are:
LeadFree Solder 100g N29AR £5.99 or 250g N30AR £9.99
No Clean Flux Disp. N63AA £7.99 Sometimes a flux pen helps but might not even need it as no SMT involved
Tip Tinner Cleaner JG06G £7.99 I like this and not the brillo pad thing GQRP sells but the little tin does appear messy after 25 hours soldering use. I replace these about cnce every 2 months.
Antex Tip Set4 3Pk N15FR £9.99 I have found lead free solder does 'eat' tips so will need one at least
Solderbraid 1mm N47FX £2.69 Small reel is more than sufficient.

I'd not expect I would need to clean the board up after with isoprop alcohol and an old toothbrush but Maplin do it in a hand spray can.
PCB Cleaner 200ml N64AN £3.49

Anyway that is what I'd use to build so pick a couple and add them into the kit you send. Any of the solder, braid, spray or flux left over I send back with the built kit.

Note what Elecraft say about solder if you don't get the Maplin one:
We recommend small-diameter (.02 to .04") rosin-core solder,
similar to Kester type 44. Solder with 2% silver is used by some
builders and will work equally well. If you use a minimum of solder,
there will be no need to clean PC boards. The use of acid-core
solder, water-soluble flux solder, or any corrosive or conductive flux
solvent is likely to damage components and/or PC boards.

If you note the K1 manual... I'd build with a print off and make notes on findings as I build, this would come back to you too. Don't send me a manual unless Elecraft say something new not available from them by PDF.
If a K1-4 that means the K1 and KFL1-4 module manuals.

Just let me know which bands you need.

A guarantee can offer is if I totally mess the build up I'll pay for the components from Elecraft to fix or buy you a new kit.

So hopefully that will answer any questions.

SDR

2010-04-22T18:38:00.005+01:00

I saw this and thought was hillarious (grabbed from here http://xkcd.com/730/ and http://xkcd.com/643/)

In addition working a lot with Simon HB9DRV and SDR-RADIO.com building the MOBOKIT V4.3 for him to use.

SDR talk/demos

2010-04-15T20:00:00.000+01:00

Done a couple of rally table/stall demos of SDR radios and asked about which ones to get/buy/build... In addition to some notes on software for the softrock SDR radios from Tony Parks KB9YIG I'll document some notes and ad them to the blog shortly.

Loch Erne Rally 11th April 2010 (Enniskillen, Northern Ireland)

2010-04-15T11:31:00.010+01:00

Just got back.

Photos of the table showing the SDR demos I ran.

I also managed some /P operation from the rally as MI1KTA/P into a 20m dipole and then on the trip back on two afternoons from the beach near Dublin as EI/M1KTA/P and managed several 2xqrp contacts. Worked qrp DX included RA1CW and 4X4FR.

Loch Erne (Enniskillen) Rally 11th April

2010-04-05T20:26:00.009+01:00

Just getting the display of kits ready.

Cannot bring the whole shack so in the box will be (everything I have soldered from kits):

The web links are current and provide info on them, some not from vendor.

HB-1A / Direct from BD4RG http://k1hah.net/HB-1A-MK-II.html
PFR-3 / http://www.qrpkits.com/pfr3.html
ATS-3B / KD1JV http://kd1jv.qrpradio.com/ATS3B/ats3b.HTM
MKARS80 & CW Adapter /G6ALU http://www.radio-kits.co.uk/mkars80page.html
BITX20A / http://www.qrpkits.com/bitx20a.html
Softrock -40 (yes the one that started the SDR craze off) / AmQRP & KB9YIG http://www.amqrp.org/kits/softrock40/
FCC-1 & FCC-2 Frequency Counter and DDS / Norcal http://www.norcalqrp.org/fcc1.htm http://www.norcalqrp.org/fcc2mkii.htm
Si570 USB DDS / G0BBL http://www.sdr-kits.net/USB/USB_Description.html
A simple keyer / ??
Tenna Dipper / KD1JV http://www.4sqrp.com/kits/td/td.htm
SLT Tuner / http://www.qrpkits.com/sltplus.html the new version
BLT Tuner / G3RJV but look here http://www.qrpkits.com/blt_plus.html
FUCHS Antenna (OK so this one I built off schematic!) / qrpproject.de
Softrock V6.2 Lite 20m /KB9YIG http://www.wb5rvz.com/sdr/New_SR_Lite/
FDIM2008 11W PA Buildathon - FDIM 2008 Proceedings.
10W PA / W8DIZ http://www.kitsandparts.com/linearamp.php
Digital Dial / http://www.qrpkits.com/freqcounter.html & KD1JV

For the SDR display will have:

Softrock V9.0 With electronic BPF
Softrock Ensemble RXTX

I might have a V6.2 & V6.3 RXTX.

I will have a few KB9YIG unmade kits for sale with me if interested.

EnsembleTRX with HB9DRV SDR-Radio Beta

2010-04-04T18:26:00.002+01:00

Just finished building and here is a short video of it working.

EnsembleTRX PA

2010-04-04T17:32:00.009+01:00

The final stage of construction.

I built this for 80m and 40m and T3 and T4 are small and the windings tight.

In both cases the bifilar Secondary(T3) and the bifilar Primary (T4) are wound first with the single wire winding being added last. You may find this a little easier.

Now usually if this were a V6.2 or V6.3 I would have added a drop of heat sink compound to the PA transistors before adding the heatsink but a plastic TO220 washer was included so I used that.

The 2N2222A TO18 heatsink is removed in this photo.

I will run a few quick tests and then clean up the boards.

Until I do as asked for them here are some high resolution pictures of the completed boards.

With no flash:

Flash:

Underside:

EnsembleTRX TX Mixer (QSE)

2010-04-04T16:21:00.003+01:00

This is 1 SMT Ic and 4 SMT C underneath and on top an additional transformer (T2) and inductor (L1), 9 resistors, 3 C and a couple transistors.

I had to substitute in for one of the 220pF caps (C21)

EnsembleTRX TX Op Amps

2010-04-04T15:25:00.005+01:00

Top

Bottom

The TX op amps are two identical sets of components for the I & Q channels to create 0,90,180amd 270 degree inputs to the TX mixer, fed from a single 3.5mm stereo socket.

EnsembleTRX PTT switching and RX circuit

2010-04-04T10:37:00.007+01:00

OK this caused me a few headaches as one BS170 was duff and so the PTT from the AVR USB was not functioning.

So I replaced the Q10 BS170 and it is now functioning fine. Lesson in there for anyone building one... watch the BS170!

Now to place the RX OP amps (actually just one IC but dual OP amps) already placed the RX mixer FST3253.

That is the RX side complete.

Now to test it.

EnsembleTRX PTT

2010-04-03T18:37:00.003+01:00

OK PTT... managed to get it worked out using Rocky... using cw mode (feel like an idiot as had tried using SSB!) Anyway on PTT in Rocky I get 5V on pin3 of the AVR. Good so far.
With no PTT enabled on the galvanically isolated RF side at the opto output with R36 and R34 in place to tap into the 13.8V line I get 10.71V (13.8V supply) at R51, enable PTT and R51 drops to 0.09V. OK that seems fine.

However if I follow the voltage signals from R51 where connects to Q9 I get 8.73V and this drops to 0.09V on PTT, L4 on PTT I get 0V wrt ground PTT or not. C27 on PTT I get 0.27V on PTT and 0V PTT off. On RX I get zero connectivity through Q10 to the antenna and same on TX.

I suspect this means Q10 is fried?

As it stands on U10 the voltages when PTT is off are:

1 0V
2 2.45V
7 2.48V
8 0V
9 2.49V
15 0V
16 4.99V

On PTT 1+ 15 become 0.1V and 0.11V respectively...

Anyone?

Softrock Ensemble TRX Modification to the Si570 output.

2010-04-03T17:10:00.005+01:00

Modification needed for the Si570 output.

Tony just let me know CLK+ (pin 4) should be connected via a 0.1uF and not direct to T1.

"...Mike Collins did a design review on the RXTX Ensemble and pointed out the a direct connection to the CLK+ output of the Si570 is not allowed in the manufactures spec of the part. The fix is to cut the trace that connects the CLK+ pin of the Si570 to T1. With the trace cut, a 0.1uF capacitor may be soldered between the CLK+ pad and the T1 via. Care should be exercised to make sure the capacitor does not short to the USB ground plane on that part of the circuit board...."

So I modified the build.

Cut a track and stripped away the surrounding PCB and soldered a 0.1uF across the gap. Ugly but it works.

This short video shows the output still fine.

Homebrew Bench Video

2010-04-03T11:26:00.003+01:00

Been asked if I have a home brew bench video.... so connected up a cheap web cam I had lying about and just pointed it at the home brew bench. This is just me tinning a new iron tip.

Softrock Ensemble TRX Beta Build Divider

2010-04-02T19:21:00.001+01:00

Now the LO has been tested as working as reported in previous blog posts (I have not uploaded a video yet showing the LO frequency tests, but I will.. it does work!)

Now to build and test the dividers.

As per Robby's website:

The Dividers stage takes in the local oscillator's signal and divides it by 4, producing two output signals. Each output signal is at a frequency that is ¼ the stage's input signal and is a square wave with 50% duty cycle. The 50% duty cycle is with respect to the regular 5V rail.

The signals are "in quadrature", that is, they are 90° out of phase with each other. These are provided to the TX and RX mixer stages as clocking signals. They are called out on testpoints marked "QSD Clk (1 or 2)", for the I and Q signals to mix down the incoming "chunk" of RF, and "QSE Clk (1 or 2)", for the I and Q signals which mix up the PC's line out signals.

On the underside two components the 74AC74 IC (U5), one decoupling capacitor

On top just two resistors added to connect to bias the offset into the divider. So the mid point signal is 50% the VCC of U5.

The Divider is tested by looking at a few things:

Check the voltage divider network across those two resistors is at 50% either side.
I get 4.99V mav and 2.49V at half way so that is right. You measure these at the hairpin bends of the two resistors R13 and R14.

Grabbing some food... back after eaten.

Softrock Ensemble TRX Beta Build LO test

2010-04-02T18:02:00.010+01:00

Now the LO is built have to test it.

Download and install SDR programs and Dynamic Link Libraries, along with hardware drivers. The actual steps anyone else might follow will vary, depending upon the operating system etc.

PE0FKO (Fred) CFGSR Configure/Control Ensemble microcontroller software
PE0FKO (Fred) SRDLL dll for Softrock controllers
The USB driver(s) for the ATTiny85 AVR/USB

(Apologies Fred should have been PE0FKO not PA0FKO as I wrote before)

If you plug in the Ensemble TRX it will (or should) immediately ask you for the drivers to be installed.

Once they are installed the system management console should have an entry for the libusb device like this.

Once the drivers are installed you can test the hardware

PE0FKO software will configure the Softrock USB/AVR/Si570 interface

The current SDR-Radio build I test the connectivity and it will select the USB/Si570 and connect to it and run it.

Soldering Si570 to softrock boards

2010-04-02T17:59:00.002+01:00

I took this to explain how to solder the Si570 chip in place.

The 8 pins 6 are large 2 are tiny.

The tiny pads getting these wrong causes about 99.99% of the problems with the Si570 not working as expected.

Softrock Ensemble TRX Beta Build

2010-04-02T16:29:00.014+01:00

I started this here:

http://m1kta-qrp.blogspot.com/2010/03/new-sdr-trx-from-tony-parks-beta-build.html

Anyway here are some photos: (BTW the boards will look terrible as I have not cleaned them up removing all the flux etc)

The reverse is of the pcb was not silk screened so here I ID the components

First thing build the power supplies.

The 5V one is easy and uses all through hole (top surface) components so I didn't take a photo of it separately. The 3.3V supply from the USB socket is a different matter though as that regulator chip is tiny:

Anyway this is what the board looks like top side with both supplies in place.

And same thing from underneath.

I ran tests on the voltages in and out and believe me that the 5V (I get 4.99V) is fine. The USB one (I get 3.31V)

Adding the LO / sI570
I have had more than a few questions about soldering the Si570. This post I explain how I solder mine in place. Apologies about the 'um err'ing in it.

Once done this is what you get the top right pad is soldered all others not and chip in place and lined up.

The board after the whole LO is built top side

bottom