Saturday, March 19, 2011

Re-packaged 80m DSB transmitter

Encouraged by the success of the 80m DC receiver built in a CD ROM drive case, I spent some time re-packaging a previously built 80m DC transmitter into another case so they will work together as a matched pair.

Front

The transmitter has the job of antenna switching.

Rear

I didn't do a very good job of arranging the boards but happily there's plenty of space.

Inside

These bits have previously let me have a contact from Sydney to Melbourne, about 700Km so I'm confident I can get a functional home built transceiver going. Last time I played with this circuit I had RF feedback troubles which I'll probably have to have another go at with it all in one box.

Front open

One problem is that the transmitter is crystal locked on 3686 while the receiver is tuneable so I'm going to need a way to "net" the receiver to the transmit frequency - presumably by powering up just the oscillator and leaking a bit of it through to the receiver.

The receiver is currently centred on 3595 for the ARNSW Home Brew group challenge, but after that's presented next Sunday, I'll move it to match the transmitter. (Peter VK2EMU has already been hinting at a followup challenge).

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