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Tuesday 29 January 2013

AD9850 DDS

I picked up on G4JNT's Feb 2013 RadCom article on the ebay AD9850 modules.

Alan's original project gives some extra information.

I obtained a couple of sample AD chips at the time and also played with the AMQRP DDS-30 and DDS-60 modules and then the PIC-ELIII development board. Most of the modules I sold at GQRP Rishworth raly.

Anyway from ebay I bought half a dozen, just turned up.... not bad for £3 a piece. This is an image of the ebay listing.

These are one of the boards.

The boards do look the same.

There are two 10 pin SIL pins either side so the boards can just plug into a breadboard. They come from china in a jiffy bag so watch out for the pins as some were bent.

An alternative method to drive is an Arduino version

Sunday 27 January 2013

CQWW 160 Contest

Was about to go qrt this morning when heard a EI6 calling right where I had been so quickly responded and bagged DXCC 23 :-)

69 (some dupes) QSO and 24 DXCC in 4 hours 11 minutes all qrp.

This is wintest sound recording of my whole contest. Sound from 22 secs in.


     1 2013-01-26 20:27:27 160         1818.5 CW   YU7AV          599 599
     2 2013-01-26 20:30:29 160         1817.0 CW   SV3RE          599 599
     3 2013-01-26 20:33:26 160         1817.2 CW   LY7M           599 599
     4 2013-01-26 20:35:27 160         1816.5 CW   F5IN           599 599
     5 2013-01-26 20:38:17 160         1815.3 CW   SN2M           599 599
     6 2013-01-26 20:46:43 160         1811.0 CW   YT0A           599 599
     7 2013-01-26 20:55:24 160         1811.9 CW   UT5A           599 599
     8 2013-01-26 21:03:33 160         1813.0 CW   9A1A           599 599
     9 2013-01-26 21:05:00 160         1813.6 CW   CS2F           599 599
    10 2013-01-26 21:08:53 160         1814.5 CW   G5W            599 599
    11 2013-01-26 21:18:48 160         1816.1 CW   9A7T           599 599
    12 2013-01-26 21:23:25 160         1818.2 CW   DL0GL          599 599
    13 2013-01-26 21:25:37 160         1818.8 CW   E71A           599 599
    14 2013-01-26 21:27:21 160         1819.3 CW   OK2D           599 599
    15 2013-01-26 21:36:21 160         1820.8 CW   DL7ON          599 599
    16 2013-01-26 21:38:48 160         1825.4 CW   HB9JOE         599 599
    17 2013-01-26 21:41:25 160         1825.7 CW   DL5LYM         599 599
    18 2013-01-26 21:44:08 160         1826.0 CW   SK7DX          599 599
    19 2013-01-26 21:45:20 160         1826.5 CW   DM0B           599 599
    20 2013-01-26 21:46:30 160         1826.8 CW   YL9T           599 599
    21 2013-01-26 21:47:41 160         1827.1 CW   PA5KT          599 599
    22 2013-01-26 21:49:03 160         1827.4 CW   DK5DQ          599 599
    23 2013-01-26 21:50:55 160         1827.7 CW   OM6A           599 599
    24 2013-01-26 21:57:41 160         1828.3 CW   G4AQG          599 599
    25 2013-01-26 22:00:18 160         1831.0 CW   OM3GI          599 599
    26 2013-01-26 22:01:55 160         1831.2 CW   9A3TR          599 599
    27 2013-01-26 22:05:00 160         1831.5 CW   YU1LA          599 599
    28 2013-01-26 22:06:05 160         1831.9 CW   F5UFX          599 599
    29 2013-01-27 05:44:54 160         1835.1 CW   ON9CC          599 599
    30 2013-01-27 05:46:56 160         1835.4 CW   S53APR         599 599
    31 2013-01-27 05:47:36 160         1836.7 CW   ON7TK          599 599
    32 2013-01-27 05:51:12 160         1837.4 CW   EA5RS          599 599
    33 2013-01-27 05:53:08 160         1841.8 CW   DL4MCF         599 599
    34 2013-01-27 05:55:27 160         1843.5 CW   DL2CC          599 599
    35 2013-01-27 06:02:13 160         1845.1 CW   S50A           599 599
    36 2013-01-27 06:09:19 160         1839.7 CW   VY2ZM          599 599
    37 2013-01-27 06:19:21 160         1839.3 CW   SN3R           599 599
    38 2013-01-27 06:21:35 160         1811.5 CW   OZ7YY          599 599
    39 2013-01-27 06:25:57 160         1812.1 CW   DJ3CQ          599 599
    40 2013-01-27 06:28:04 160         1814.1 CW   OL4W           599 599
    41 2013-01-27 06:29:23 160         1814.6 CW   9A1P           599 599
    42 2013-01-27 06:32:58 160         1816.0 CW   DR1A           599 599
    43 2013-01-27 06:36:50 160         1816.0 CW   DK6WL          599 599
    44 2013-01-27 06:38:28 160         1816.0 CW   OM7M           599 599
    45 2013-01-27 06:52:18 160         1818.4 CW   OK1DCF         599 599
    46 2013-01-27 06:54:56 160         1818.8 CW   9A4M           599 599
    47 2013-01-27 06:56:40 160         1819.9 CW   I1EIS          599 599
    48 2013-01-27 06:58:09 160         1822.1 CW   DM0B           599 599
    49 2013-01-27 06:59:52 160         1824.4 CW   E7DX           599 599
    50 2013-01-27 07:02:03 160         1827.3 CW   S51V           599 599
    51 2013-01-27 07:03:30 160         1827.8 CW   DR4W           599 599
    52 2013-01-27 07:09:16 160         1831.6 CW   DL5AXX         599 599
    53 2013-01-27 07:10:34 160         1831.6 CW   DL6RAI         599 599
    54 2013-01-27 07:16:01 160         1843.0 CW   DJ9CN          599 599
    55 2013-01-27 07:19:17 160         1843.0 CW   F5BBD          599 599
    56 2013-01-27 07:24:44 160         1843.0 CW   EI6IZ          599 599
    57 2013-01-27 18:45:20 160         1843.0 CW   OK5Z           599 599
    58 2013-01-27 18:45:42 160         1843.0 CW   HA30S          599 599
    59 2013-01-27 18:46:42 160         1843.0 CW   S53O           599 599
    60 2013-01-27 18:47:46 160         1843.0 CW   OL7M           599 599
    61 2013-01-27 18:51:50 160         1843.0 CW   OM7RU          599 599
    62 2013-01-27 18:56:20 160         1843.0 CW   DL0CS          599 599
    63 2013-01-27 18:59:40 160         1842.2 CW   DL0GL          599 599
    64 2013-01-27 19:10:35 160         1841.0 CW   G3UHU          599 599
    65 2013-01-27 19:13:26 160         1841.0 CW   UZ2M           599 599
    66 2013-01-27 19:18:00 160         1841.0 CW   SM5CZQ         599 599
    67 2013-01-27 19:19:36 160         1841.0 CW   DL1DTL         599 599
    68 2013-01-27 19:22:20 160         1841.0 CW   DL3DTH         599 599
    69 2013-01-27 19:24:29 160         1841.0 CW   LY2W           599 599
    70 2013-01-27 19:30:59 160         1836.4 CW   HB9ARF         599 599
    71 2013-01-27 19:32:24 160         1835.3 CW   DL1ET          599 599
    72 2013-01-27 19:34:47 160         1832.2 CW   DK5DQ          599 599

160m was/is very lively. Dies a bit during daylight. I woke up at 5:30 am
(went QRT at 10pm) and went to the shack just to see if things
improved. The shack is COLD COLD COLD and 50m from house and no
heating so looked like a Michelen man!

Not sure why couple comment about it being really hard work.. still I never managed any NA stations (except VY2ZM), heard some (on the recording) and JA's. Almost every station came back first call (no kidding) sometimes some fluff on the exchange. This morning I even thought what the heck and called CQ :-)

KX3 and only 5W into a Z11Pro (not the internal KX3 ATU) into the LF
longwire (140ft abt 20ft AGL).

Sure plenty will beat my score but it is the taking part that matters.

I even sat on 1.843 (QRP CoA) for a bit, see my log. Not really S&P more like
rotate tune up khz or so find next station, wait for the blah TEST and send
M1KTA and sometimes full response othertimes ?KTA

Friday 25 January 2013

472KHz KX3 Transverter - update

Few emails about this so a couple more comments:

1. It seems Elecraft have not got the XV transverter functionality working as it might be expected in the KX3. In K3 one option is to use the internal 10MHz as a LO which would be rather nice but that is not  available ffrom KX3 at this time.

2. LO will be using a crystal oven. The 472KHz band is 7KHz wide so drift is not an option.

3. No I do not intend including a power output as per XV but I expect that could be added.

4. I 'might' allow input power up to the full output from the KX3 so 12W but it would be safe to stick to lower input. Some sort of intelligent attenuation will add a lot of complexity.

The likely LO will be 28MHz put that down to availability of LO and other components.

Thursday 24 January 2013

472KHz KX3 Transverter

Started to layout a manhatten construction last night, I might transfer to a PCB and 'pretty' the build eventually. I am going to use my KX3 as the RX and drive of the TX side of a 472KHz setup. I also have an Softrock V6.2 I modified for 500KHz already but it is a bit high I can lower it a bit which might be good as a second RX and sort of panadapter.

The KX3 will require an external transverter setup as the LPF would never fit inside.

The design is loosely...

RX side:
A main HF band colpitts LO, exact frequency will be down to the mixing schema and the KX3 transverter options then use a DBM either one made from torroids and diodes or a packaged version I will look at 602/612 and ADE-1 or and SBL-1 to mix UP the RX 472KHz signals to the KX3 RX IF. It all depends on the response to tests. I have a 500KHz xtal in a test oscillator that I can pull DOWN and I will add attenuation so can do the typical 1uV and 50uV S meter calibration tests to determine which has the better response.

On the TX side:
Use the same HF band LO as RX, and DBM (decision to be defined) to mix DOWN the KX3 TX IF to 472KHz. As G3XBM has pointed out and it is in the spec sheets you need to limit the input power to the mixers to c10mW so I will need to 'play' with attenuation. The output will be followed by a 1W PA and then a 25W PA using IFR510 and output LPF similar to the GW3UEP versions in an earlier post. SM7UCZ gave me some interesting BUZ MOSFET so I might also try one of them.

ATU (see G3XBM ferrite rod design) and antenna will as per 500KHz either be /P beach thing using a 10m pole and loading coil (I used a 2 litre coke bottle wound with tapes every 10 turns) or a 140ft LF long wire I have used successfully at home, with a homebrew variometer made from a section of 6" Yellow gas pipe (when they replaced the mains to the street I asked for an off cut if they had one and was given a couple 6 foot lengths!) and a smaller 3" white PVC pipe that would go inside.

The easiest HF LO to choose might be 28MHz so that the dial reads 28.472 to 28.479 giving 472 to 479 KHz but as I mentioned it depends on the KX3 transverter setup Elecraft said if you want 472KHz build a transverter and use 7MHz IF.

I have a second KX3 that does not have the AUTO ATU so will need to make sure the transverter matches well.

KX3 RX on 472KHz directly is poor so you could not use it as you might an FT817. As the circuit has not been released and there is no obvious place where you could inject a 472KHz RX signal. I am sure it is possible but it is not recommended that you  bypass the KX3 front end filters that will effect normal operation.

It 'might' be possible to control from the KX3 menu system..

From KX3 manual..Revision B4 June 1, 2012
Copyright © 2012, Elecraft, Inc.

Page 5

Keyline Out and GPIO (ACC2)
The 2.5-mm stereo ACC2 jack provides a keyline
output (ring contact) and a general-purpose 3-volt
logic signal (tip contact).
The keyline output goes low during transmit, and
can be used for transmit/receive switching of linear
amplifiers and transverters. For keyline voltage and
current limits, see Specifications.
The general-purpose signal, GPIO, can be set up for
various equipment control functions. For example,
it can send band-change information to Elecraft
XV-series transverters. See the ACC2 IO menu
entry for a full list of uses for this signal, as well as
hardware interface requirements.

Page 9

Transverter Bands
Nine user-definable bands are provided for use with
transverters. These can be used with the Elecraft
KX3-2M internal 2-m module, Elecraft XV-Series,
or other transverters.
The KX3 does not have a low-level
transverter output; transverters are driven from
the main antenna jack. This requires the use of
transverters that have a common receive/transmit
antenna jack and associated T/R switching. Consult
the transverter manual for drive power limitations
and switching requirements.
The ACC2 jack provides a keyline output for
keying transverters. The ACC2 jack also provides a
GPIO pin that can be used to select among multiple
transverters based on the band selected at the KX3.
This is further explained below.

Transverter Band Setup

Transverter bands are set up using the XV menu
entries, as follows:
? Locate the XVn ON menu entry. Tap 1 – 9 to
specify which transverter band to configure. Set
the parameter to YES to enable band n.
? XVn RF sets the operating frequency (MHz).
? XVn IF specifies the I.F. band (7, 14, 21, 28, or
50 MHz). Use 50 MHz for the KX3-2M option.
? XVn PWR sets maximum KX3 power output
for the current transverter band in watts (0-1).
Use 0.3 watts for the KX3-2M option.
? XVn OFS can compensate for frequency offset
in the transverter’s oscillator. (An offset is not
required for the KX3-2M module, since its
oscillator signal is derived from the KX3’s
main synthesizer. If there is a frequency error,
calibrate synthesizer using REF CAL.)
? XVn ADR should be set to TRN 0 for use with
the KX3-2M module. It can also be used to
specify an optional Elecraft XV-series
transverter selection address. Only addresses
TRN1-TRN7 are recognized for this purpose.
To select XV-series transverters using this
method, set MENU:ACC2 IO to TRN CTRL,
and connect the ACC2 jack’s GPIO pin to the
transverter’s auxBus line.

Page 35


Determines the function of the GPIO signal (ACC2 jack, left side panel):
OFF (output, 0 V), ON (output, 3 V), LO=PTT (input; apply 0 V or ground to
activate PTT), HI=PTT (input; apply 3 to 5 V to activate PTT), LO=Inh (input;
0 V inhibits transmit), HI=Inh (input; 3 to 5 V inhibits transmit), TRN CTRL
(output; XV-series transverter control using Elecraft auxBus prototcol). If the
GPIO signal is inhibiting transmit, the TX icon will flash as a reminder.

NOTE: External interface circuitry may be required. The GPIO pin is a 3-V
logic input/output with a 500-ohm series current-limiting resistor. It is tolerant of
0-5.5 VDC when used as an input. If a voltage outside this range is to be used,
insert a larger series resistor. (Example: when an RS232 RTS signal is used to
activate PTT, use a 2.2 to 10 K series resistor.) When the GPIO pin is used as an
output, its 3-V logic high may not be sufficient for use with some equipment. In
this case a 3-V to 5-V level translation circuit can be used.

Page 37

{band} In

Allows you to remove one or more bands from the BAND rotation. Use BAND
up/down to select bands, then set them to In or Out using VFO A. (Works with
transverter bands, too.) You can still get to mapped-out bands using memory
recall, direct frequency entry, or computer-control commands.

Page 39


If set to NOR, TUNE power level follows the POWER knob. Otherwise,
establishes a fixed power level for TUNE, overriding the present POWER knob
setting. Note1: TUN PWR does not pertain to ATU TUNE , which always uses 2
or 3 watts and is internally controlled. It also does not apply to transverter bands
using the low-power KXV3 output (XVTR OUT).

Page 40


Tap 1 – 9 to select the applicable transverter band (1 - 9). Set parameter to YES
to turn the transverter band on.


Lower edge for transverter band n (1-9); 0-24999 MHz. (Tap 1 – 9 to select
applicable transverter band.) Normally, 144 would be used for the K144XV
internal 2-m module. But if the K144XV is being used as an IF for a higher-band
transverter, you can set it to the lower edge of the higher band.


Specify KX3 band to use as the I.F. for transverter band n (1-9) . (Tap 1 – 9 to
select the transverter band.) I.F. selections include 7, 14, 21, 28, and 50 MHz.
Use 50 MHz for the K144XV internal 2-m module.

H 0.1

Sets upper limit on power level in watts for XVTR band n. Applicable only to
external transverters, not the KX3-2M module. Tap 1 – 9 to select band.
The KX3 does not have a low-level transverter port, so external transverters must
have their own T/R switching and be able to handle the specified power level.

Offset (–9.99 to +9.99 kHz) for transverter band n (1-9). (Tap 1 – 9 to select
transverter band.) Compensates for oscillator/multiplier chain errors in external
transverters. Not applicable to the internal KX3-2M module, which derives its
signal from the KX3’s synthesizer.


Assigns optional band-decode addresses to transverter bands. Addresses TRN1-7
can be used to select Elecraft XV-series transverters if the ACC2 IO menu entry
is set to TRN CTRL and the transverters are connected to the ACC2 jack
(tip=auxBus, ring=key out). TRN0 is used with the KX3-2M module (internal).
Tap 1 – 9 to select the transverter band; rotate VFO A to select the address.
To configure an Elecraft KX3-2M 2 m module as XVTR band 1, set XV1 ON to
YES, XV1 RF to 144 MHz, XV1 IF to 50 MHz, and XV1 ADR to TRN0. The
XV1 OFS and XV1 PWR menu entries are not applicable in this case.

Tuesday 22 January 2013

472KHz TX

 Mine is based on the 472KHz VFO and 25W PA from GW3UEP.

I have the PA from the 500KHz TX that is in this blog based on a M0MBU design as well.

The capacitors and IC I picked up from Rapid.(Bought 2 sets)

Line No.  Product Code  Description  Quantity  Each  Total
1 83-0354 4024b 7 Stage Binary Counter         2 £0.358 £0.716
2 83-0380 4049ub Hex Inverters/buffers         2 £0.262 £0.524
3 10-1455 6n8 100v Polypropylene Capacitor 8 £0.126 £1.01
4 10-1795 1uf 100v Mks4 Poly Capacitor Case L 2 £0.271 £0.542
5 10-1805 100n 250v Mks4 Poly Capacitor Case B 4 £0.148 £0.592
6 62-2162 22k 0.6w Metal Film Resistor - Pack of 100 £1.63 £1.63  

I have a number of variable capacitors and a die cast box fore the VFO stage.

Monday 21 January 2013

5MHz & 472kHz NoVs

Yippee... after being monumentally stupid and entering the wrong email address so the NoV ended up in some void I was sent them...

So I expect to be qrv on 472KHz and 5MHz shortly.

I will not run some MOPA station (i.e QRSS or WSPR beacon) but will be a real op at a key (472KHz) or on a mic (AM 5MHz).

Will try a modification of the ZL2BMI on 5MHz perhaps..

Saturday 19 January 2013

PS-SPS250A back to life

Replaced the NPN transistors but no change....

So went further and looked as discrete resistors about the transistors (R5,R6,R7,R8,R9,R10,R12)... one of the 1/2w resistors was open circuit. (R6) Visually did not look like there was a problem. Value was 2.2ohms 1/2W so not one I have normally but I do have 1/4W versions... so I did the parallel/series dodge and using four 2R2 1/4W made up a 2R2 resistor.... I have at least 1/2W capacity and should be fine.

Rebuiilt and plugged in, switched on and supply jumped back into life... :-)

Those transistors are rated at 15A and 25A surge, the power supply is supposed to be 25amp... hum... so I think I'll be careful.

Thursday 17 January 2013

Appear in RadCom QRP column for 6W and C5 trip

Rev George Dobbs (G3RJV)  has added my note to him about C5 and 6W trip with new KX3 last Summer to his RSGB QRP Column. It perhaps shows that DX trips are not only for those with a dozen members and 400W although maybe not that rare a location. Given recent events maybe I should have tried harder for TZ.

Hoping to manage a couple trips this year.

BERU in March (9th/10th) hoping to get away from all the snow and ice and will be somewhere suitably warm, QRS and QRP only of course.

First will be Portugal CT (Not that DX but I'll be on a beach again), might also try to get to ZB2 but not sure if can be QRV. I will be in Sweden during June and last w/e in July planning to be on an island off UK coast line (puffins and seal allowing of course). Later in the year hoping for something more DX though.

Monday 14 January 2013


Notes (as asked).

Needed to be up 08:00 - 18:00 UTC or 17:00 - 07:00 Local time so nearly all the operation was overnight.

Local sunset was about 6pm local time with dust between 5:30pm and 7pm, total darkness after that until runrise near 6am.

I visited several stores in Pago Pago, a hardware store  just past the MacDonalds on the road towards PAgo PAgo centre from Sadies where I bought the battery jump leads I used to recharge the KX3 batteries.

The SUV I rented was from Dollar. You REALLY need to arrange rental cars well before arriving as they usually all get rented out between the flights (bi-weekly) into and out of American Samoa.

On the North side of American Somoa main island, north east shore beach nights of 8th, 9th and 10th October. QRV 07:00 UTC 8th (about 3am local time masts broke), 05:00 UTC 9th (mast broke again during night) 05:39 RV9CPB was first QSO followed by UN7TW and 06:02 UTC on 10th.

Both before 8th and after 10th I operated from the South shore near Sadies.

Long way for 3 nights operating :-)

Similar to 6W and C5 operating for 15m and 20m frequencies were:

14.055 CW although I was QRV 14.015-14.035 as well (G3SXW recommendation).
21.055 CW although I was QRV 21.015-21.035 as well (G3SXW recommendation).

The beach location would be great for 40m, 80m and 160m but when I was there the night time winds were too strong to allow me to support the 10m poles I had taken for a phased 40m/80m antenna and broke, if I had planned better before hand (trip was very hastily put together) I would have made sure I had adequate guys. There is plenty of availability of stranded insulated wire, e.g. US mains zip cord can be obtained in long lengths from numerous locations as well as various guy cord as the island main export is tuna so there are hardware stores selling all manner of suitable materials.  The local garages and car sales all have surplus, some brand new but not current model, car and larger vehicle batteries as there is no local recycling so a power supply that is suitable to float charge one of these batteries might be advisable. Note they WILL BE much more expensive that might be obtained in EU/UK or US. I never found a source of long poles although it was possible to obtain lengths of Aluminum and Steel tubing up to 2" diameter from some of the hardware stores.

It would seem that a number of business were still effected by the 2009 Tsunami that ruined much of the island. See this for an idea what it was like:


Have been asked for a few words about KH6, where, when and what frequencies I was QRV from KH6/M1KTA.

I hired a car from the Honolulu airport and drop through Honolulu pased Diamond Head and Hanama Bay (I had been to both on a previous trip), follow the coast for a while longer and just as you start to head up the NE side of Ohau you will come upon a layby with a number of 'surf dudes' complete with VW camper vans etc and a layby off the main road.

I pulled in and at the far end of the car park stopped next to and between a row of tal palm trees.

At 08:38 local/18:36 UTC QRV from Sandy Beach, NE Ohau

After listening to the bands I started a CQ at 18:46 UTC (08:46 local)

Frequencies & Modes operated:

21.015 CW
18.075 CW
18.130 SSB
24.895 CW
14.015 CW
10.105 CW
7.005 CW
28.055 CW

40m and 80m had no disernable signals.

All 5W from my KX3 #1082 into a W3EDP (84ft & 17ft counterpoise) hung vertically  up one and then horizontally between two tall (30ft+) palm trees at the edge of the car park on the shoreline right by Sandy beach. A good operating location for any that look for one in the future.

Sat in the shade by the car I was operating with power coming from the battery of the rental car using a set of jump leads, as the KX3 had no other power. The car was left running whilst I operated.

QRT just after 12:00 local time, completely forgot to take a photo of the setup but did take a photo of Sandy bay (because the QSL card) and returned to airport for flight to Houston where I met up with AE5X.

Sunday 13 January 2013


I'll be CT1/M1KTA/P between 9th and 17th Feb.

Wednesday 9 January 2013

PS-SPS250A Power supply

Transistors arrived from CPC.

Follow original here.

Note that both are open and one had cratered.

Tuesday 8 January 2013

KX3 RF board

This is the RF board of my KX3 before I start building.


Sunday 6 January 2013

si570 in KX3

Was asked... what is the Si570 in a KX3...

Thursday 3 January 2013

472KHz Nov

Just applied for my 472KHz Nov.

I'll be trying the VFO from with the PA I built for 500KHz.

Arrrgh used wrong email address... NoV still processing.

paying licence fees for The Gambia before you arrive

Asked this a few times so I post it here, you will have to confirm with PURA if these details are still correct though. I take no responsibility if they are wrong.

I got this from PURA. 94, Kairaba Avenue, P. O. Box 4230 Bakau, The Gambia Tel. (220) 4399601 / 4399606 Fax: (220) 4399905 E.mail  Website

Type Approval Fees Payment to PURA Account

The method of payment will be by cheque or cash transfer from either a USA bank or a London to the following PURA accounts:

1.       From a USA Bank
BANK:                          HSBC BANK USA NA
ADDRESS:                   452 FIFTH AVENUE, NEW YORK

FED WIRE:                   021001088

SWIFT CODE:               MRMDUS33


SWIFT CODE:               GTBCCMGM

ACCOUNT NO:              000141526

                                    ACCOUNT NO: 201-108594-201 

2.       From a London Bank
BANK:                          HSBC BANK PLC LONDON

ADDRESS:                   8 CANADA SQUARE
                                    E14 5HQ

SWIFT CODE:               MIDLGB22


SWIFT CODE:               GTBGGMGM

SORT CODE:                40-05-15

IBAN:                            GB61MIDL40051558979540(EURO)

ACC NO:                       58979559 (GBP)
                                    58979540 (EUR)
                                    58979567 (USD)

                                                                                    ACCOUNT NO:  (201-108594-110)

Wednesday 2 January 2013

SPS250A power supply

Small error lead to quite a problem...

A SMPS I take on trips I forgot is NOT auto voltage sensing on input and was still set to 110V after recent US trip... plugged it in and lets just say it died and let out the magic smoke, oops :-)

Pretty obviously the power transistors got fried and rather than junk it I thought I should fix it

This is dealing with mains voltage so do not do this unless you know what you are doing as the voltages are lethal.

It took a bit of digging to find the circuit diagram (thought it was on the pdf that came with it), still haven't found it exactly but this is very similar except mine appears to run the fan full all the time instead of having a fan control board on the lower right here.

This is closer

These power supplies are widely in use and all are called SPS250A in the name and are all made in China under various names... so if yours has SPS250A in the name and looks like mine then chances are it is the same but no responsibility if it is not, use information at own peril (and this is running at mains voltage which can kill so do not do this without a healthy respect for high voltages).

This is the same supply just a different brand name 'MyDEL' mine says Sharman.

The two NPN power transistors 2SC2625 were removed still attached to their heatsink.

Note all the common mode filtering on the input side (top right corner).
Mine has had the right hand transistor crater and the other is short circuit between the pins.

I'll add the photo of mine shortly.

Anyway suffice to say power supply can be easily repaired.

2Sc2625 were available from a number of sources but ebay was the cheapest.

I hear that it might make sense to replace the 2Sc2625 10A versions with 2Sc3220 which are 15A versions but I could not source them when I looked but they are also on ebay often enough.

Shack PC

Over Xmas the shack PC failed... so the shack website has gone down so anyone that had noted designs (I see the download logs)

It seems that something got too hot the northbridge on the motherboard failed :-)

I have a new video card and water cooler for the CPU coming.

I'll get the website back up shortly.