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.

Belgium gets 4m allocation

With immediate start all radio amateurs in Belgium holding a full licence have access to 69.950MHz (+/- 5kHz) with 10W EIRP on a non-interference basis.  If you can read French or Dutch there is more information here.

New WSPR DX record tonight (40m)

Trying out WSPR2 on 40m this evening and just got a report from VK6POP at 14465kms, which is a new DX record for me. I was running 5W to my 500kHz antenna tuned via the Elecraft T1 ATU. It must work pretty well on 40m!

First experience with WSPR 2 (new version)

Well, it works. I deleted the old version from my PC and installed V2 tonight. Set-up was straightforward and I like the slider to set the TX percentage. Also 500kHz is now one of the default listed bands (600m). My first TX was spotted (with the new version) by I2IAL on 40m.

WSPR 2.0 now available

WSPR 2.0 introduces a number of new features including a  user-friendly setup screen with drop-down selection of audio devices and rig-control parameters, support for compound callsigns, fine selection of the fractional time for transmitting, and a Tune button.  A new Advanced setup screen offers optional CW identification and tools for frequency calibration and automated frequency corrections for your radio.  Full details are presented in the WSPR 2.0 User's Guide, which you will need to read in order to use the new features.  For the first time, a binary installation package is made available for Ubuntu Linux (versions 8.10 and later), Debian 5.03, and other Debian-based 32-bit Linux distributions.

WSPR available at http://physics.princeton.edu/pulsar/K1JT/wspr.html 

Sunspots - blimey!

Just seen the sunspot count for today - 29 - which is pretty good for where we are in the new cycle. It is very clear that sunspot cycle 24 has got into gear and next year should show considerable improvement on bands like 10m.