Friday, 15 August 2014

Wispy Complete?


I have just finished building, to Roger G3XBM's design, the receive chain. This is a very simple direct conversion receiver, based around a f/2 Polyakov mixer, fed from the same 14MHz oscillator that drives the doubler for the transmit side.

The lower half of the board is the receive side. The mixer and RF amp is to the left, with the oscillator above. This is followed by an audio amplifier chain. The only change I have made to Rogers design, apart from the bit of coax from the Tx/Rx diode switch to the RF amp, is to use a 220nF cap to couple between audio stages, where Roger used a 470nF. This is simply due to the fact that I have no more capacitors higher in value than 220nF left!

I will rig her up for testing in a little while.

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