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Wednesday, 28 August 2013

Öland Fieldday Buildathon

From Nyheter från Radiomuseet Nr 56, 1 september 2013

Monday, 26 August 2013

That mast for the Camb-Hams guys

The cover.

In use 2004, one closest to camera. We had a wire dipole strung between them.

Thursday, 22 August 2013

DX operating it is good for the weight

Found an old picture...

2008 (3B8)

2012 (KH8)

I seem to have lost weight! Maybe I have discovered the diet that works...DX operating  :-)

Added a shack webcam

It takes a picture every 5 seconds or so and updates that webpage (that refreshes if you keep it open).

I am going to be changing the shack shortly so it is full of boxes right now.

There are a couple of cameras and the images are uploaded to a remote server so for security purposes I have a recording of what is going on in the shack and outside it.

Wednesday, 21 August 2013

More buro cards just gone out

Just sent out buro cards for M1KTA/6W/P and C5/M1KTA.

Direct requests had dried up.

Tuesday, 20 August 2013

What does a pile up sound like from the DX end?

As I record most things when I am operating I have some interesting audio files.... I usually only keep them long enough to confirm QSL or for any talks etc but I was asked did i have anything from the 6W trip as I was very loud into parts of EU. Anyway here is a file...

Sounds of Sengal and The Gambia

I was going through old files and found this from one of the places I stopped at on the way. Much of the music (outside the tourist areas at least) uses this sort of story telling.

The track was recorded so might not be perfect.


West Africa was a lot of fun, did not understand the language, I am sure the story was explained to me at the time, but just listening to it brings back memories.

This was by Konte and Kuyateh who play a huge drum with strings and sing along. It is called a Kora. There are known as Jali's, a Jali is a 'storeyteller'and they carry on the tradition much as generations had done before them. Singing about the past and the current situation of their friends, family and country. Some of the 'songs' were a tad political!  I had someone local drive me about and he explained that stories and history are passed down from generation to generation by this method within families and groups of friends, ensuring survival of such stories for centuries.

This was from a CD of music picked up in one of the cafe's we passed. The music just jumps out at you and after having seen it first hand captures the West African/Mandinka people very well.

Memories ... a day away from pile ups... the day started with a long drive through bright red dusty roads, out of Kariba, past the odd herd of animals on the side of the road,a stereo is playing this and others, hanging from a bungee in the cab, it is very hot and sometimes very sunny.... It will rain in a couple hours as it is rainy season and the humidity is about 80% already... there are dark clouds on the horizon and there is a huge thunderstorm building, the static on air was enough to give up after a couple of hours in the dawn. We are on the coast road well south of Banjul near the Sengalese border, just stopped at some fishing shacks and fed on spiced fish and rice..far from the usual tourist places...  I understand why the VooDoodes used to come back here year after year, so much to see and every time you go on air more contacts that you can possibly make.

FT817 ... bringing it back from the dead.

OK looks like the main processor needs lifting from the board and that is a multi pin device.It is the square IC in the picture above. The response was that this mmight not be an economical repair... :-)

So got to find out can I obtain one new or is it a bespoke FPGA thing? Yaesu tech services have said I can get one but might be easier to let them fit it.

I think I will be sitting with it on the bench and the service manual and working out if all the voltages are where they should be. (I suspect this has already been done) If the main voltage went high and regulators were damaged then there is a chance the cpu and PLL do not have the correct voltages appearing, or were damaged.

Doubtful I can do much more harm to it now so I will remove the TXCO, filter, PA and BHI modules and walk through the service manual and the expected voltages.

Friday, 16 August 2013

Fahnstock Clips

50 Fahnstock Clips just turned up for old vintage rigs. (and a few modern creations).

The clips hold wires in place and have a pincer action.

If you know what they are then it will be great to hear that you can get new ones.

Paul was great at sending these to me and accepted paypal. Postage is a bit high (USPS not Paul). but these are hard to get. Paul has the original kit that will make these.

SM7UCZ put me onto these.

Thursday, 15 August 2013

transformer tester

I was reminded that a simple 555 timer can create an astable oscillator that can be used with a DVM to measure a transformer windings when at a rally or when there are no markings.

The values for R1, R2 and C1 will give you the frequency and the duty (charge/discharge).

t1 = 0.693 (R1 + R2) x C


t2 = 0.693 x R2 x C

Where, R is in Ω's and C in Farads.

You might then follow that with a simple op amp integrator to turn the square wave into a sine wave.

Or another option without the op amp so a similar small component count is a saw toothed oscillator.

The frequency of the circuit is:

f = (Vcc-2.7)/(RxCXVpp)

Vcc is the supply voltage and Vpp is the Vpp of the output voltage.
The transistor can be almost any GP PNP.

Sunday, 11 August 2013

Component Tester - new enclosure

Further to an earlier post where  I commented on the component tester I found some more information about them and just put mine into an enclosure.

I bought a few desktop console enclosures a while back. Not much needed done just extend the display, add  some better terminals and a button.

This was a photo of how it had been done elsewhere:

I'll post photos of mine here.

Some more detail of it are here:

Mentioned recently (April/May) on several email lists with detailed comments as “ROC” or “PROC” tester on Yahoo group qrp-tech

Designed originally by Markus Frejek, and pimped out by Karl Kubbler with some cool software mods, this inexpensive little board does some wondrous measurements! 
Vendor “lemonbleue”, Ebay item no. 330855732011 listed as”NEWEST Transistor Tester Capacitor ESR Meter Inductance Resistor NPN PNP MOSFET ...
Apparently cloned by Chinese manufacturers

Manual available as “ttester.pdf” in files section of qrp-tech or HERE

Series of manuals and software for original design and upgrades can be found at

Beware of similar items as not all of them are the latest version with resistor matching function and ESR testing ability.
Cost is under $30.00 with shipping to US

Tests resistors, capacitors above 1000 pF, inductors above 10 uH, and many semiconductors and most importantly ESR of capacitors above 10 uF.

Very handy for bench testing, matching audio and power inductors and capacitors, identifying semiconductor pinouts and characteristics. Not suitable for most RF inductors and capacitors.
1. Operates with ATmega8, ATmega168 or ATmega328 microcontrollers.

2. Displaying the results to a 2x16 character LCD-Display.

3. One key operation with automatic power shutdown.

4. Battery operation is possible since shutdown current is only about 20nA.

5. Low cost version is feasible without crystal and auto power off. With software version 1.05k
the sleep modus of the Atmega168 or ATmega328 is used to reduce current if no measurement
is required.

6. Automatic detection of NPN and PNP bipolar transistors, N- and P-Channel MOSFETs,
JFETs, diodes, double diodes, Thyristors and Triacs.

7. Automatic detection of pin layout of the detected part.

8. Measuring of current amplifcation factor and Base-Emitter threshold voltage of bipolar transistors.

9. Darlington transistors can be identifed by the threshold voltage and high current amplifcation

10. Detection of the protection diode of bipolar transistors and MOSFETs.

11. Measuring of the Gate threshold voltage and Gate capacity value of MOSFETs.

12. Up to two Resistors are measured and shown with symbols and values with up to four
decimal digits in the right dimension. All symbols are surrounded by the probe numbers of the
Tester (1-3). So Potentiometer can also be measured. If the Potentiometer is adjusted to one
of its ends, the Tester cannot di er the middle pin and the end pin.

13. Resolution of resistor measurement is now 0:1, values up to 50M are detected.

14. One capacitor can be detected and measured. It is shown with symbol and value with up
to four decimal digits in the right dimension. The value can be from 25pF (8MHz clock, 50pF
@1MHz clock) to 100mF. The resolution can be up to 1 pF (@8MHz clock].

15. For capacitors with a capacity value above 2 F the Equivalent Serial Resistance (ESR) is
measured with a resolution of 0:01
and shown with two signi cant decimal digits. This feature
is only avaiable for ATmega with at least 16K ash memory (ATmega168 or ATmega328).

16. Up to two diodes are shown with symbol or symbol in correct order. Additionally
the ux voltages are shown.

17. LED is detected as diode, the ux voltage is much higher than normal. Two-in-one LEDs are
also detected as two diodes.

18. Zener-Diodes can be detected, if reverse break down Voltage is below 4.5V. These are shown as
two diodes, you can identify this part only by the voltages. The outer probe numbers, which
surround the diode symbols, are identical in this case. You can identify the real Anode of the
diode only by the one with break down (threshold) Voltage nearby 700mV!

19. If more than 3 diode type parts are detected, the number of founded diodes is shown additionally
to the fail message. This can only happen, if Diodes are attached to all three probes and at
least one is a Z-Diode. In this case you should only connect two probes and start measurement
again, one after the other.

20. Measurement of the capacity value of a single diode in reverse direction. Bipolar Transistors
can also be analysed, if you connect the Base and only one of Collector or Emitter.

21. Only one measurement is needed to nd out the connections of a bridge rectifier.

22. Capacitors with value below 25pF are usually not detected, but can be measured together with
a parallel diode or a parallel capacitor with at least 25pF. In this case you must subtract the
capacity value of the parallel connected part.

23. For resistors below 2100
also the measurement of inductance will be done, if your ATmega
has at least 16K ash memory. The range will be from about 0:01mH to more than 20H,
but the accuracy is not good. The measurement result is only shown with a single component

24. Testing time is about two seconds, only capacity or inductance measurement can cause longer

25. Software can be configured to enable series of measurements before power will be shut down.

26. Build in self test function with optional 50Hz Frequency generator to check the accuracy of
clock frequency and wait calls (ATmega168 and ATmega328 only).

27. Selectable facility to calibrate the internal port resistance of port output and the zero o set
of capacity measurement with the self test (ATmega168 and ATmega328 only). A external
capacitor with a value between 100nF and 20 F connected to pin 1 and pin 3 is necessary to
compensate the o set voltage of the analog comparator. This can reduce measurement errors
of capacitors of up to 40 F . With the same capacitor a correction voltage to the internal
reference voltage is found to adjust the gain for ADC measuring with the internal reference.

Saturday, 10 August 2013

Long wire

I was asked if I had any more info about the long wire I use at qth and I have updated the original post withy some video I took.

mini 1 1/4" metal springy (aka slinky) - what on earth can you use these for?

I discovered I had two of these mini slinky coils.

They are 1 1/4" (c33mm) diameter and XYL had just finished BOTH the tin foil and the cling film so I had a pair of identical cardboard tubes.

A quick test and I can slide the tubes inside the mini-slinky and stretch it out and connect to it along the length (about 12"/300mm). You cannot actually solder to it but you can wind wire about it and solder that in place.

So I am going to make a couple of multi tap inductors for antenna experiments..

/P on Marsden Moor before Rishworth 2012

Just before Rishworth 2012 I went up on Marsden Moor and had some fun /P with KX3 and a short 6m fishing pole....  was sent an email that I do plenty of IOTA and DX but why do I not do any SOTA. So here is a photo diary of one activation. Cannot remember the hill but was fun and amazing I was in the North of England and it is sunny and dry!

 Canal path to the start up..

 You had to cross this cute bridge. Was used for  pack mules (that used to be used bfore the canal tunnel through the hill.

Nice views from the top...

On the top.

That's me hiding in the long grass.

Series of QSO with JA, I had the KX3 still tuned to 17m which I had used in KH8 or KH6 cannot remember which now.

Walked on and there was this rock thing.

 Walking back down..

So that is it a SOTA activation.

I thought travel to a DX was a lot for a couple hundred qso... SOTA seems like even more effort for maybe 10's of qso. Take along radio kit and it is usually very wet and windy so making qso is not easy. As I live in Cambridge and there are no hills in Cambridge (!) and Stansted airport is closer to me than any hills (figure out the time to get to places etc) so I can do the DX thing much easier than I can get to a hill somewhere.

Friday, 9 August 2013

Homebrew VP6DX like vertical dipoles for that next DX trip

I was intrigued by the antennas of the VP6DX DXpedition and I met up with some of the VP6DX team at RSGB conference in 2009/2010 and asked a few questions about the antennas and more importantly saw some better photos of them. Unfortunately I pretty much forgot the topic in the intervening years but I had bought some 4m poles and then some 6m telepocket poles (search this blog) with the express meaning to make up some of these 2 element phased vertical dipoles. A CDXC member directed me to the site by F4BKV recently that has more details.

I did not try to work VP6DX when on their trip but I heard them, and I have used vertical dipoles by the sea and added parasitic elements on a separate pole and used vertical moxons and the like on trips, all worked fine and the advantages of the sea are obvious but had a draw back in that it was slow if not impossible (especially whilst operating) to amend the 'path' of maximum radation and RX signal.

After trying a few options the most successful was a central vertical dipole and then sloping unconnected wire dipoles suspended in a sideways V format, initially taped to the antenna supports spaced 120 degrees from the centre.

(Maybe a diagram and photo here?)

This was attempted with the guys at SK7CA field day on EU-037 with a decent central mast when they successfully used three dipoles on 17m and were able to apply the directivity. The velocity factor in all the wires is important and a lot of trimming was required to get it to work. It works but the directivity is still very broad.

When I rediscovered the box of poles in the shack I thought time to look into this one more (and the idea for a /P cubic quad but more of that in a later post). Time to try and make something similar to the VP6DX (but much lighter) antennas that I could carry in 'normal' luggage.

The demo version of EZNEC is adequate for this purpose and I came up with a few permutations. The real challenge was trying to work out how to support the horizontal section and to make the cross arms as light as possible without adding too much weight.

The basic antenna has to use a 12m DX wire pole or one of two DX Wire short 10m poles (last were recently obtained from sotabeams). The cross members are shakespeare 4m fishing poles.

One of my build is yet to be put on the scales but the construction is light.

Right now these are MONO BAND ONLY.

As everyone has said that goes on any trip to an island and from my own experience get right by the sea and use a vertical the performance using the sea as part of the antenna is so much better. On one occassion in SM recently I went as far as putting the antenna support INTO the sand with a foot of sea water above it and a further 3 feet or so until the lowest part of the element, there was no tidal flow of the sea or it might have been interesting! The shoreline was a mass of very smelly some rotting stinky sea weed and this presented as a mat under the antenna the results were very good signals. But alas no directivity so I could hear stations I could not/did not want to work and that meant I had constant QRM for those I did. (Search this bog back a few weeks for the SM/OZ and IOTA trips for more details of that antenna)

Anyway time to do the analysis:

First BIG assumption, you need a good ground, I for this purpose said the ground was perfect, sea water is not exactly a perfect ground but it is very close. If you cannot get the antenna right by the sea then a vertical needs a large wire ground mat and the performance will not be as good as modelled here. I repeat if you are a mile from the shoreline forget it... you need to be RIGHT AT THE SHORELINE.

Don't believe me try a simple experiment next time you are at the seaside with your /P setup and build the simplest vertical dipole. Listen and TX right by the sea then before propagation changes too much move a mile inland (not down a river or similar) and do the same... you will soon see why renting a holiday home with sea views but a mile from the beach is great idea but for radio simply not worth it. Unless you use a different antenna.

My second BIG assumption is that the path away from the antenna in the direction I want is also all sea so for several wavelengths (even better if just sea most of the way).

Anyway these were the patterns I was looking for.

I used Conductivity (0.0303 S/m) Diel Const 20 which are EZNEX Very Good Ground values. In some locations the sea water is MUCH 'saltier' so these might be better, or the reverse.

Insert EZNEC 15m or 20m diagrams here...
Normal vertical dipole
Vertical Dipole plus 105% Longer Parasitic

Vertical Dipole with 105% Longer Parasitic with ends closer 

The antenna has a lot of forward directivity, also notice a major null 180 degrees in the reverse direction. This is useful for so many reasons the major one being to null out qrm/qrn and it also means you will be able to tell if you have Short Path or Long Path propagation. Which for DX trips matters!

Your antenna site may have to be carefully chosen , Google Earth can help you a lot before you get there (a 5 minute decision whilst driving past also works!) so if you can put NA/JA or EU etc into this main lobe you will have a lot more success.

Hint: REMEMBER TAKE A COMPASS AND A GREAT CIRCLE MAP FOR THE DXCC YOU WILL BE IN. Buy a compass and put it in your /P kit bag.

On EU-138/EU-029 at times it would have been useful to be able to null out RA/UT stations 'behind me' as I was working NA. Likewise EU as I was working JA. I am sure I do not have to explain this to those who have used directional antennas before. On KH8 I found a perfect NE shore beach and I operated from there, placing my vertical dipoles on the beach and my tiny (to some) qrp signal, did manage some EU/UK qso it might have sounded so much louder with one of these.

I'd rather add dB to the antenna signal strength and not dB to the TX output.
Multiple reasons but I am a QRP fan and that means you can operate often without any electrics and only batteries.

As per the vertical Moxon experiments I did a while back (search blog for Moxon) and that Pete M provided analysis for (put link here) you will not that over a perfect ground the angle of maximum radiation is very low.

More to follow....

Tuesday, 6 August 2013

KX3 - IQ SDR + Panadpater AND RTLSDR with HF converter

Got an old (ish) laptop and going to add it to shack QTH and KX3 setup as a generic SDR panadapter. I have a nice USB sound card (48 KHz 24 bit) that has an isolated input adapter (simple 1:1 isolation interface) and the laptop seems to run SDR# on the laptop (Linux Ubuntu) (screen shots to follow).

I also have a USB RTLSDR RX and a HF converter so I am going to set it up along side as a SDR grabber which should run on the same system.

The Linux/Mono run version of SDR# is not that efficient so it is a bit kludgey (aka slow and stutters a bit) so I'll be experimenting with alternative Linux SDR options:


GNU Radio (which I have never got to work as I think it should)

I'll add some front end BPF to the SDR when I am QRV from the shack.

Why do this?

Kanga (UK not US) have asked me to review a couple of their SDR RX kits for 80m so I'll be building those pretty soon and blogging the details. The kits once built will be given away at G-QRP convention (aka Rishworth)

Thursday, 1 August 2013

QTH station back on air

It is hot but taken all I have learnt on trips and starting to put antennas up. qrv on 15m this afternoon. Vertical dipole, with  parsitic dipole (so 2el) can switch between EW and WE qrp (5W) rbm immediately picked up by W3LPL.