Bluebell woods

Just spent a pleasant afternoon walking through an old wood near where I used to live in Devon. The woodland floor was a carpet of bluebells and garlic flowers. This is the first time I'd been back there in around 40 years and it was as lovely as ever.

Ultra low voltage oscillators

Thinking a bit more about my crazy idea for a mains hum powered QPRp beacon TX, I chanced upon this page which discusses FETs running from extremely low voltage supplies. See http://www.dicks-website.eu/fetosc/enindex.htm. Some of the zero threshold voltage MOSFETs (ALD110900A) used in sensitive crystal sets may also be useful in this application. The link shows an FET oscillator powered by just a thermocouple producing only 13mV! Incredible. See also http://cap.ee.ic.ac.uk/~pdm97/powermems/2009/pdfs/papers/069_0209.pdf and http://www.aldinc.com/pdf/Ultra%20Low%20Power%20Oscillators.pdf

UK trains - actually pretty good

For the last couple of days I've been down in Canterbury visiting my son, his wife and our grandson. As my wife was busy I took the opportunity to travel alone by train. There is now a new high speed service from London to Canterbury that has slashed journey times on that part of the trip. All trains were clean, on-time, fast and comfortable. Also, at £25.50 return with my senior railcard, excellent value. We complain too often, but railways in the UK are actually rather fine of you can travel off-peak when the commuters are not crammed in. As an ex-trainspotter back in the late 1950s and early 1960s I still love trains.  Secretly I'd like a Ian Allen locospotter's book (now Platform 5 books) so I could collect numbers still, but would risk being called a sad anorak!

325km with 50uW ERP on 137kHz

Well, Henny PA3CPM has just sent me a new screen grab showing my signal at 1041z today on 137.676kHz in QRSS30. This time you can make out some of the CW (visible just below the continuous Loran line) and the periodicity between callsign blocks is visible confirming this is indeed my signal.  Distance is 325km (202 miles) to JO22mb square. This is the first time my 137kHz signal has got into mainland Europe. I am amazed that a really simple beacon on a tiny board into a simple wire loop in the garden can span such distances. Even more amazed that Henny could find it!

Over 100km on 137kHz with 50uW ERP

Just got a screen grab from G3WCB 101km away showing my QRSS30 beacon signal being received at his QTH near Windsor. Mine is the lower trace in which you can see "BM" (part of XBM). It is not strong, but there. I will leave the beacon running with around 50uW ERP during today.

A few hours later G3WCB got me stronger with the XBM very clear on the screen.

Henny van Elst in Holland was also seeing traces at the right frequency, but too weak to positively identify.

QRSS3 beaconing on 137.6748kHz

My QRSS30 (slow CW) LF beacon has just been started up. I'm hoping that QRSS30 will get me reports from a bit further afield.  Any reports and screen grabs would be much appreciated. It will be on for much of the weekend unless I need the antenna for some VLF tests. The message cycle takes about 25 minutes and best results will be with Argo, Spectran or Spectrum Lab software on a PC and FFT bandwidths of around 0.1Hz.

Message:     XBM in QRSS30, pause, then G3XBM in 10wpm
Freq:           137.6748kHz
ERP:           50uW (antenna 80sq m vertical loop)
Location:    JO02dg, Burwell Cambs

2 transistor transceiver kit

The Four State QRP Group is offering the new "HamCan" transceiver kit for sale at just $30.  It is a 2 transistor crystal-controlled CW transceiver, delivering 0.5-1W TX power with enough sensitivity and selectivity to receive plenty of signals. They claim it is a minimalist yet good performance transceiver. The kit features a high quality PCB, low parts count and fast and easy building. It is claimed to be an excellent kit for first time builders. It has been selected as one of the ARRL Midwest Convention's Buildathon kits. 

More information at http://www.wa0itp.com/hamcan.html .

Mains hum powered beacon

Recent tests with earth electrodes at VLF have got me wondering about a simple QRSS HF/VHF beacon TX powered entirely from the rectified mains hum and other crud coming from a couple of earth rods in the ground.  Not sure of the available power, but I suspect it would be in the 0.1 to 2uW region, maybe more. This may be enough to drive a low voltage QRSS beacon for example. You can buy power harvester ICs these days for this purpose, but with a step-up mains transformer there may be a volt or two available at a few tens of uA and that alone may be enough to drive a keyed oscillator. The ultimate in free power beaconing!

3km DX on 8.97kHz WSPR today

This morning I successfully decoded a VLF earth mode WSPR signal from G6ALB at a distance of 3km. Signal was quite strong, but for some reason the WSPR software refused to decode it (apart from once) despite clocks being reset at each end. This is my best WSPR DX reception on VLF so far. Andrew was running 40W to an earth electrode antenna. I was copying him on an earth electrode antenna although the WSPR signal was stronger later on the 80m square vertical loop in the garden.

In the afternoon I used my wife's laptop and WSPR decoded every time at -16/-17dB S/N, a very decent signal. There is a video showing the VLF WSPR set-up if you want to see it. 

G3XBM is off to Mars

NASA is collecting names to be put on a microchip that'll be on the Mars Science Laboratory rover heading to Mars in autumn 2011. The rover has special CW indentations on its wheels spelling out  JPL (Jet Propulsion Laboratory).

To add your name/callsign go to http://marsparticipate.jpl.nasa.gov/msl/participate/sendyourname/