500kHz transverter rebuilt (and working)

This morning I rebuilt the 500kHz transverter in readiness for putting it in a small case. It fits comfortably on a 4 inch by 3 inch single sided piece of copper laminate built "ugly style". The unit worked first time and it has already received 4 WSPR spots from G3ZJO at lunchtime today.  The car keys give some idea of how small this unit is.

SAQ (17.2kHz) - on line receiver

Dec 10th the transmitter at SAQ (Sweden) on 17.2kHz is transmitting a special CW message. Also there is a transmission on Dec 24th. An on-line SDR in The Netherlands that can be used to listen to this. See  http://websdr.pa3weg.nl/ .  Alternatively, try listening with a simple up-converter or simple VLF receiver. 

Extra transmission on 10th December
In order to celebrate the 100th anniversary of the Nobel Prize to Guglielmo Marconi and Karl Ferdinand Braun, we plan to be on air on 10th December at 08.00 UTC and 16.00 UTC. No reports are required and no QSL-cards will be given.

Traditional transmission on Christmas Eve 24th December
SAQ will be on air on 24th December at 08.00 UTC. The frequency is as usual 17.2 kHz CW. Reports are welcome and will be confirmed by QSL-cards.

Latest sunspot predictions (from NOAA)

The very latest table of predicted sunspot numbers for cycle 24 have just been published on the NOAA website. They show a peak of 90 (+/-10) in May 2013. According to the table, the sunspot count will have risen to 45 by this time next year, so we should be assured of some regular USA contacts on 10m next autumn.

500kHz transverter (breadboard) photo

This is a photo of the 5W 500kHz transverter breadboard in its "raw" state. In the next couple of days it will be rebuilt tidily into a small aluminium project box and should look a lot neater. Still, isn't it amazing that something this rough on the bench top can work so well and be heard 951kms away!

Power harvesting IC - runs off 20mV produces 5V

This week's Electronics Weekly has a link to Linear Technologies new power converter IC (LTC3108) that can run from 20mV and deliver 5V. It is designed to be used with Peltier effect devices and similar sources of low voltages, but it could be used with the DC power derived from a crystal set.

Weather and 500kHz antenna matching

It surprises me how much my antenna matching changes depending on weather, temperature etc. I use my simple ferrite rod ATU for the main antenna tuning (tapping down the coil for best antenna and TX connection but I make final adjustments using my little Elecraft auto-ATU at the shack end of the feed coax to the remote ATU in the back bedroom near the antenna. If it rains or the weather is cold, I need to rematch the T1 ATU to get best SWR.  I guess this is all due to the ground losses changing in wet weather as a result of changes in soil conductivity.

A new report from Germany on 500kHz

Last night I was copied, just, at -30dB S/N, by Veit DL7ET in JO31 square at 468kms. This is now my 47th unique station report on the band (well 49 if you include 2 CW contacts). At some point soon the antenna for 500kHz will have to come down so I can re-erect my 28MHz antenna, but maybe not for a couple more weeks.

The next QRP project?

Having finished the 500kHz transverter to my satisfaction I'm mulling over the next project "big idea" to keep me amused on a winter afternoon. I do want to build some homebrew gear for 28MHz as this remains one of my favourite bands: antennas are small and unobtrusive, DX is not hard to work with QRP when the band is in good shape, and the frequency is low enough to be able to make gear, and get it working, with my limited test equipment. Maybe I should do it in stages:

1. A direct conversion mixer and back end with CW/SSB filter bandwidths.
2. A direct-conversion 28MHz front end mixer and RF filter based on an SBL1 or NE612/602.
   
3. A stable mixer-VFO covering the CW and SSB part of the band.
4. A driver and PA for up to 5W.
5. A DSB mixer module to use with the above to use in a simple DSB transceiver.

Scottish DX on 500kHz

After no luck on CW I returned to 500kHz WSPR and was immediately rewarded with 3 spots including one from GM4PMK in the west of Scotland in IO66 square some 615kms to the north west of me. He's spotted me before but this is my first report from him in several weeks. He is reporting Andy G4JNT some 20dB stronger than me, which is consistent with the difference in ERP (Andy is running 200mW ERP and I am running around 1mW ERP).

500kHz CW activity tonight

Several DX stations on tonight on 500kHz CW. OR7T was calling LA3EQ (recently allocated the band in LA) and OZ8NJ was a good signal working G3DXZ. So far tonight, with all this excitment, no-one has heard my 1mW ERP signal on the key! WSPR is much easier!