5W (from the PA) on 500kHz

With the arrival of some IRF510 FETs I've built a small PA to go on the end of my WSPR beacon transverter. The output (from the PA) is now 5W, so my ERP should be up by around 10dB to around 50-60uW. Already I have been spotted by G7NKS some 10dB stronger than ever before - most encouraging!

The first transistor - read Shockley's lab notes

Take a look at William Shockley's hand written lab notes at Bell Labs when he created the first point contact transistor back in December 1947. Little did he know then what this would lead to in the next 60 years. Amazingly the patent wasn't filed until 1951. Who actually invented the first transistor is debated and was the result of separate discoveries and hard work by many. This is often the case in science.

500kHz WSPR - last time before improving the station

This evening and overnight I am running my 500kHz WSPR beacon for the last time in its unmodified state before beginning to make improvements to the antenna and PA. I am still hopeful that I'll get another one or two new stations spotting my signal. Once the ERP starts to be increased by up to 20dB my "sphere of influence" on 500kHz should increase.

Do listen on 500kHz WSPR and upload any spots you get.

POSTSCRIPT: I did actually fire the "old" setup again last night (Friday evening) for a few hours but was only reported by G7NKS. I'm now thinking of practical and relatively unobtrusive ways of making the signal a bit more potent on 500kHz without the garden looking like Droitwich or GBR Rugby.

A new station hears my 500kHz WSPR QRPp

This evening I received reports from G0BPU in Ipswich on 500kHz WSPR, This is now the 5th station to have heard my 6uW ERP signal. I am still hopeful that I will beat the 100kms barrier before I start the station improvements. Other reports today came from M0BMU and G7NKS. My best DX remains at 69kms.

500kHz WSPR restarted - please listen

In the coming weeks I shall be improving my ERP, but to get a baseline I've just restarted my 500kHz WSPR beacon which is believed to have an ERP of around 6uW (microwatts). Since starting it up I've already received reports from M0BMU at 69kms away with S/N levels ranging from -24 to -29dB. These are the levels I was getting last month, so all is still working (see picture of the WSPR database).

If you are able to listen on 500kHz WSPR set you receiver to 502.4kHz in USB mode and click "upload spots" on the WSPR screen so that your SWL reports will be added to the database on the internet automatically.

It really would be good if more people listened on 500kHz WSPR even if they can't TX. WSPR is very easy to use especially on RX and the WSPR software can run in the background whilst you get on with something else. The WSPR software can be downloaded from http://physics.princeton.edu/pulsar/K1JT/WSPR112.EXE

All reports really would be most welcome.

161kms voice powered QSO by AA1TJ

Just got an email from Mike Rainey AA1TJ describing his TX powered only by his voice. He achieved a distance of 161kms with a germanium transistor oscillator putting out a few mW of power. The power for this was generated by rectifying the audio signal from the loudspeaker used as a microphone. In the end Mike resorted to a sort of MCW mode shouting CW into the LS but W1VZR copied this and made a recording. Mike is also looking at a receiver using "RF harvesting" to allow a receiver that requires no DC power source other than that derived from off-air RF.

Mike's amateur radio pages are at http://mjrainey.googlepages.com/radio

Free power QRPp transceiver or beacon?

The idea of powering a low power receiver, or even a transceiver or QRPp beacon, from free, otherwise wasted, RF energy that is all around us appeals to me. A few people have been toying with this idea and there are even some commercial ICs likely to appear which "harvest" energy from stray RF and even vibrations. The circuit shown here is from the excellent site by KE3IJ (R.Andersen) and shows how to use 50 or 60Hz mains "fog" and stray RF to power a simple receiver. See http://www.tricountyi.net/~randerse/nopower.htm .

See also Ben Tongue's crystal set pages for a circuit using a supercap to store harvested energy which is then used to power a micropower op-amp.

A "harvester" QRPp transceiver or beacon which derives its energy from stray RF, storing this is in a supercap and allowing brief periods of transmission at very low power is worth developing I think. I have not seen such "harvesting" circuits used to power a transceiver or beacon before but for a uW level beacon this should be feasible.

GQRP Club SPRAT 140

The latest copy of GQRP's quarterly magazine SPRAT arrived here today and it was nice to see my little Sixbox 6m AM transceiver featured on the front cover, alongside my car keys! Also in this edition was my article about WSPR weak signal beaconing. Since the article was written back in the summer I have been using WSPR almost daily on all bands from 500kHz up to 50MHz.

Just £6 annually gives you GQRP Club membership with 4 article-packed issues of SPRAT magazine a year, as well as access to the GQRP QSL bureau and club sales items such as toroids, QRP frequency crystals, transistors and ICs at good prices. As a GQRP club member, you can get a CD with all 140 editions of SPRAT magazine for just £4. It's worth joining just for this alone. If all other magazines had to go then SPRAT would be the one I'd still get as it is the best.

Rybakov Wideband Vertical Antenna

For those looking for a simple vertical antenna that can cover a wide range of HF bands you might want to try the Rybakov antenna. This is what IV3SBE says about it:

"Multiband NO TRAP NO GAP Antenna. This Antenna is a small wonder, easy to build and allow you to work all HF spectrum with your TRX and it's internal ATU. It consist of a matching device at it's feed point to enable lowering the impedance of a randow wire. Winding 14-18 turns of twin insulated wire 1.75mm over an AMIDON T-200-2 RED Toroid type and wiring as the image on your right will enable you to perfectly feed the radiating element . Once finished, place it in a waterproof plastic casing used for electrical wiring suitable for UV radiations. Complete it utilizing a SO 239 socket and two Stainless Steel Bolt to ensure long life under external condition. Connect, to the Wire Terminal, a lenght of wire ranging from 7,6m onwards depending the frequency range we would like to obtain. With 7,6m we can easily cover from 7Mhz upwards, for better performance we suggest to leghten the wire up to 8,6 > 12m so to have a better performance staring from 3.5 Mhz. The Antenna will perform well in vertical position utilizing a retractable fiberglass pole ( we use a 9m fiberglass fishing rod ) so to deploy the Antenna in seconds just hook the wire to the top part and extend the elements fully. You are now ready to operate ALL BAND NO GAP making use also of the internal ATU of your TRX for portion of band where SWR is above 2:1. See Below the Antenna fully extended and in Action during a short Portable Expedition."

See http://www.iv3sbe.webfundis.net/html/Rybakov806.htm

IC703 TX failure

After many years of excellent service my IC703 decided to expire on TX last night: power started to drop when running 5W on 30m then 80m (good matched load), then nothing, although I could detect a signal on the FT817, probably at mW levels.

I believe this is a common IC703 issue. Does anyone have data on how to fix this and where I get the spare parts? I believe it is either a driver or PA failure.

Incidentally Martyn Lynch quoted £45/hr plus parts and shipping to do a repair. I don't expect I'd see any change from £100.

This is the first time in 42 years of operating that I have had ANY piece of amateur gear fail, confirming that generally equipment is reliable if used carefully, so I cannot complain.