8 Sep 2010 – Home-Brew Stroke-P by John Cooke GM8OTI

In his Presidential Address John began by explaining that his main interests in amateur radio are VHF and up, simple “home brew” radio equipment, and portable operation. He talked about how he got started in the hobby and how limited facilities for aerials at home had led him to portable operation including SOTA – Summits on the Air – and the need to build his own equipment tailored to these requirements.

 

 

 

John showed all the items that he had built over the years since he was first licenced in 1978:

First rig – 2m FM portable – and he still has the circuit diagrams!
HF linear amplifier — IRF510 push-pull – 24V supply – 35W on lower bands

2m linear amplifier – BLF245 – 24V supply – 25W out.
6m linear amplifier – IRF510 × 4 – 36V supply – 50W out

The use of 24V or 36V (rather than 12V) supplies was necessary to achieve the required power output from the devices.

At last – above 1GHz – an RF sniffer (which he used to test for leakage from his microwave oven)!

Microwave wavemeter
23cm Transverter
More compact 23cm transverter

Future plans:

– 23cm PA, integrated into transverter
-13cm transverter with PLL / synthesised LO
– Phasing method SSB driver
– Hardware for a software defined radio

John described the constructional techniques he has used over the years, from the valve days to “dead-bug” and veroboard to printed circuits with surface-mount components. He plans to produce printed circuits photographically soon.

John has built all his antennas for portable work on VHF, UHF and HF, using readily available hardware, configured to reduce to a size that fits his back-pack, which he demonstrated:

 

Click for John’s slide-show (.pdf).

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