AA1TJ's "Code Talker TX" - all voice powered

Mike Rainey continues his work on purely voice powered transmitters, in which just the energy in his voice is used to power the RF circuits i.e. no batteries or PSUs at all. He's achieved well over 100kms on 80m this way using a form of CW derived by whistling into a loudspeaker to generate the energy needed. Here is an example of his signal received 109kms away. He can clearly be heard "keying" (actually whistling!) the words of "Mary had a little lamb" in CW.

A good evening on 500kHz QRPp

This evening my 500kHz WSPR beacon has been running from 1700-2300z, still with less than 1mW ERP. As the map shows, this is not preventing 8 stations in 4 countries copying me and many at considerable distance. There has been some transatlantic propagation this evening with SM6BHZ and OR7T being copied in Canada already. These are distances I can only dream of with my tiny station!

A 19th reporter on 500kHz

G4EFE managed to hear my WSPR beacon on 500kHz several times last evening (127kms) bringing the total number of unique stations receiving me to 19 now. I still have work to do to get over the 1000kms distance target.

500kHz - an 18th station hearing me

This morning at around 0930z I received a new report for my 500kHz WSPR beacon, this time from G0HNW who is 200kms away. This brings the total number of reporters to 18. 16 were via the WSPR database and a couple of others via the RSGB LF reflector. Clemens DL4RAJ has been looking for my signal for many nights but thinks I need a further 10dB of ERP before I reach central Europe.

CQWW contest summary - 10m was great

With darkness falling now 10m is going quiet after an exciting 2 days. In the end, my 5W SSB and halo antenna worked 35 stations in 20 countries. DX from outside Europe was not workable this time but I was hearing CX, PY, ZS, 6W, etc so conditions were definitely not bad. Although there were a couple of stateside stations worked from Europe, I did not manage to hear them. The slight upturn in sunspot activity came just at the right time.

10m - the return of the good days?

The CQWW SSB contest has livened things up on 10m this weekend, but the sunspots are also showing signs of activity again and the band generally has been in good shape. In the last 24 hours I have heard DX from 4 continents and confidently expect it to open to the USA this afternoon. Good signals from 9J2B0 on CW and ZS9X on SSB today as well as wall-to-wall Europeans from 28.38-28.62MHz at times. Could this be a sign of the good times to come? Let's hope so as 10m is one of the best allocations we have on HF and a great band for QRP DXing when conditions really improve.

500kHz TX schematic (5W)

This is the current schematic of the 500kHz TX down-converter I use for WSPR. It uses an IRF510 FET PA and generates about 5W from the PA stage, although the ERP is only around 1mW from the antenna. I am planning to add the RX converter stages and an RF sensing circuit so I can use other modes in full transceive on 500kHz. The input is my FT817 at 500mW on 28MHz which is mixed down to 500kHz in an SBL1 mixer.

G0NBD and G4FDD log me on 500kHz

My 500kHz WSPR signal has been logged by new reporters G0NBD in IO83 square (261kms) and G4FDD in IO93 square (212kms) tonight.. This now brings the total number of different stations that have heard me to 16. Not bad with <1mW ERP.

10m - CQWW SSB DX Contest

This BIG HF contest runs this weekend and is sure to make the bands sound busy. I shall be having a go with 5W SSB on 10m only and see what happens.

By 1600z Saturday I'd worked 24 stations in 16 European countries with 5W QRP SSB including C4I, P33W, 4L0A, US5D and TM1O. It is nice to hear 28.4-28.55MHz crowded with stations. Funny how "conditions" magically improve when there is a big contest! In the afternoon there was some decent DX about including LU1HF and PW5G but I did not work them.

EPAD FETs and low voltage TX

This application note shows a 32uW oscillator using EPAD FETs that works with 0.5V supply and may be useful for "harvested energy" TX circuits. The ALD110800 FETs used has also been used to power an amplifier with just a 0.2V supply.