6m WSPRing and aeroplanes

Just been active on 6m WSPR this morning running 5W to the vertical colinear. The only person to report me, several times, so far has been G3ZJO who is 79kms to the west of me. What is most interesting are the number of multipath 6m signals seen on the WSPR waterfall with large amounts of Doppler shifts. G3ZJO has been analysing these are has made predictions about the aeroplane flight paths which would result in such traces. Here is the WSPR screen when receiving G3ZJO through an number of such multipath and Doppler shifted traces.

Simple beacon keyer IC: the K-ID2

Looking around for a simple beacon keyer to use with a QRSS beacon, I discovered the ICs sold for $6 (available via Paypal) from K1EL. This 8 pin IC looks ideal as it allows a variety of pre-programmed messages to be selected and sent at predetermined keying speeds.

See http://k1el.tripod.com/KID.html . At $6 each you can hardly go wrong with this. I shall be ordering a few shortly.

Another new country on 500kHz WSPR

My 500kHz WSPR beacon has now been heard in a fourth country: a -26dB S/N report from F5WK who is in the Paris area, a distance of 436kms away to the south. The beacon has now been reported by 11 different stations in four countries so far.

Lambda diode circuits

Mike Rainey AA1TJ has some good tunnel diode ideas on his pages but these devices are hard to find these days. Instead one can create a negative resistance device called a Lambda diode with a couple of FETs or an FET and a transistor. See for example the pages of Ramon Vargas Patron at http://www.zen22142.zen.co.uk/Theory/neg_resistance/negres.htm where he has examples of oscillators and regenerative receivers using Lambda diodes.

500kHz WSPR - a summary so far

So far, spots have now been received from 10 unique reporters (9 via the WSPR database + G3YMC's report using WSJT7 not shown here) in 3 countries and 7 grid squares.

If I could summarise what this tells me it is:

(a) WSPR works very well at 500kHz allowing weak QRPp signals to be detected.
(b) Very low power (ERP <0.3mW) and electrically tiny antennas do work on 500kHz if weak signal modes are used.
(c) 136kHz is worth a go next, even with the poor antenna and very low ERP.

A map to end a fantastic day on 500kHz QRPp

This is the map that says it all: DX that even yesterday I would not have believed possible with a true QRPp microstation on 500kHz WSPR. I go to bed very happy, leaving the beacon running overnight in case any others manage to detect my signals.

K1JT, Joe Taylor, thank you for bringing us this wonderful software package.

What next - 136kHz WSPR?

Having now almost achieved more than I could ever have expected on 500kHz WSPR with uWs ERP, I'm wondering if I should give 136kHz a try with the same antenna and transverter. If I could maintain the same antenna current (20mA measured) my ERP would be around 3-5uW on 136kHz. I'm wondering how far that might get. Almost certainly not too far, but probably enough to be detected by some of the nearer stations

Even greater DX on 500kHz QRPp WSPR - 896kms!

This is getting unbelievable now with such low power and a simple antenna: having just got a report from OR7T I've just now got one at -26dB S/N from GM4SLV in the Shetland Is all of 896kms away! This has been one of the best days ever in my ham radio life.

International DX on 500kHz WSPR

Just received my first 500kHz report from outside England at -26dB S/N from OR7T in JO20ix which is 337kms away.

Using the formula in the RSGB LF Handbook I just calculated my ERP on 500kHz assuming an effective antenna height of 6m (probably less than this in reality) and a measured antenna current of just 20mA. It works out at 315uW ERP. Based on earlier measurements by M0BMU it should now be around 60uW. I suspect he is nearer than the theory suggests. Anyway, still a long way below 1mW ERP even but getting great results with WSPR.

One Laptop Per Child (OLPC)

Good to see that Uruguay has become the first country to provide a laptop for every child attending state primary school according to a report on the BBC News website today as part of the OLPC Initiative.  Over the last 2 years 362,000 pupils and 18,000 teachers have been involved in the scheme, which aims to provide low cost, but high specification, laptops to school children across the world.