10m/40m WSPR

This afternoon, for a change, I've been putting out a signal on 10m WSPR as my vertical on 500kHz can be resonated on 28MHz using the Elecraft auto-ATU. So far nothing heard here and no reports.

All was quiet so I moved to 40m where instant reports at 5W, then 500mW, from all over Europe. Now testing at 50mW output.

New grid square and station report on 500kHz

Just got my first WSPR report from Brittany, France from F5JNV in IN98 square at 427kms. This is now my 41st report so far on 500kHz. A 42nd report was received from a G SWL a few minutes later.

SAQ (17.2kHz): extra transmission Dec 10th 2009

There will be a CW transmission with the Alexanderson alternator at SAQ on 17.2 kHz on Dec 10th 2009 at 08:00 UTC and again at 16:00 UTC the same day.

The reason for the extra transmission is a centenary commemoration of the Nobel Prize given to Guglielmo Marconi and Karl Ferdinand Brown. SAQ does not want QSL-reports this time and will not verify. They still intend to continue with their annual transmissions on Christmas Eve (morning), Dec 24, at 08:00 UTC with tuning up from 07:30 UTC.

This is always a great opportunity to try your hand at VLF CW reception either with a simple up-converter, direct conversion RX or even a software receiver totally implemented on a PC.

Back on 500kHz WSPR (TX)

Having just got some more IRF510 FETs from the GQRP club I've rebuilt my 500kHz PA and got it working properly towards class E. As long as the antenna is close to 50 ohms the PA hardly gets warm (on a WSPR TX cycle at 5W RF from the PA) as the efficiency is now so good.

Will run the 500kHz WSPR beacon overnight tonight then plan to modify the PA and ATU to 136kHz for a few days. 136kHz WSPR tests will run over the weekend if things go to plan. ERP will be even lower than on 500kHz, but I'm hopeful of some reports. If you get a chance to listen and report (via the WSPR database) I'd be most grateful.

The new TX PA is working well: I've had a 0dB S/N WSPR report from F6CNI near Paris!

RXing on 500kHz this evening

Although I cannot TX on 500kHz at the moment (should be back on next week), I am listening again this evening and hoping to copy G3ZJO who is testing his station on WSPR. Not heard him yet but will keep listening.

Off 500kHz TX for a few days

Our little 2 year old grandson has come to stay for a few days, so I'm unlikely to get much operating time until Sunday evening. I have to rebuild my PA before I can get back onto 500kHz TX, so it may well be next week before I'm on the band again. I shall try to listen as and when I am able. The main information I've gathered on FET PAs (especially in class D/E) for 500kHz is to make sure the antenna is well matched (i.e. don't adjust the ATU/matching when the PA is on), don't exceed the peak voltage rating on spikes, ensure that parasitic oscillations are well suppressed and be generous with the heatsinking.

Another oscillator calculator

Harry Lythall SM0VPO has a most interesting site full of ideas. Among the useful stuff is an oscillator calculator which allows you to work out values of L and C to make an oscillator that Harry claims always works. The circuit produces about 20mW.

This is the link http://web.telia.com/~u85920178/blocks/osc7m00.htm

500kHz WSPR - back to 100uW ERP

Having blown my 3rd IRF510 PA because of overheating, I decided to go back to my 700mW PA based on a 2N3906/2N3904 pair until I rebuild the transverter with a decent heatsink. This PA is bullet proof!  Having made antenna improvements since I last ran this ERP, it will be interesting to see what reports I now get. So far, just M0BMU and G7NKS at -10dB on the reports when running 1-2mW, so all is as expected.

WSPR and DXCC

The following is an extract from a posting on the LF reflector and may suggest getting QRPp DXCC may have become a whole lot easier:

"The discussion at the RSGB meeting noted the ARRL’s position that essentially if two stations make WSPR reports with each other and this is confirmed by QSL or some other approved method then there has been a two way exchange of call sign, report and other info e.g. locator and that qualifies as a QSO for DXCC purposes."

This may surprise some, and did me.

Does anyone know precisely what the ARRL has said regarding DXCC qualification and WSPR? By the definition above I "worked" VK6POP with a few watts of WSPR on 40m earlier this week.

As someone pointed out, a lot LESS data is exchanged in an HF contest, when often the callsigns are not sent (very often) and reports are meaningless. At least with WSPR you get the full calls, location and QTH locators exchanged.

Blown my 500kHz PA ......again

My IRF510 500kHz PA has a tiny heatsink (soon to be addressed when a new heatsink arrives) and it is not very tolerant of poor antenna match. As a result it died again this evening in mid WSPR! This afternoon I managed to raise to PA output to 8W by changing values and this must have made the tiny heatsink just too small to be useable. I also need to find a better way of getting my antenna tuned to 50 ohms.  This is all a good excuse to do a proper rebuild next week.