Thursday, 19 September 2013

Transformer Troubles

Well, much Rf work was put aside for some time, whilst the show was got out the way, and the FT-857D was sent of to Geoff at Castle Electronics to be fixed. Also during this time, I myself underwent a 'gentlemans procedure' and all thoughts of radio were off for a few days.

The show was a pretty good success. Operating predominantly on 40m SSB, we made a couple hundred QSOs. 2m FM showed itself as suspected to be pretty much a lost cause. Bob M1BBV and Steve G7TAO both came to help out, and their assistance was very much appreciated, as was the dual band handie from Steve!

So now I can get back to a bit of RF engineering. The Wispy 10m WSPR transceiver is first up for completion. All the transmit side is now built, as can be seen below
But, its not yet operational. With no AF input, im still seeing lots of output, but also lots of harmonics. AF input doesnt seem to have any affect. Although the spectrum analyser says the 28MHz signal is strongest, the Marconi 2955 doesnt register it, but instead shows a few tens of mW at about 43MHz. I suspect that theres a problem with the RF transformer in the mixer. The PA is obviously taking current, as its getting hot, perhaps a bit too hot!

I think the transformer must be the culprit, and i'll take it off and have a look.

Further to the show station, the thought occurs that since were held in the grounds of the Deaf Trust, we should be demonstrating at the station ways in which the hobby can be enjoyed  by those with hearing problems. So, im starting to investigate digital modes, with the idea of operating a digital station next year. It seems either old fashioned RTTY, or PSK31 are the modes to choose.

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