Monday, May 10, 2010

80 meter DC Rx step 3 - VFO built and working

Built up the VFO yesterday, put it on the frequency counter. Seems to even been in the right part of the band. I drew up the circuit on a little note pad, however I miss drew the tuning inductor and the tuning capacitors. So after assembling most of it, I thought that I would double check the original photo and noticed that my selection of capacitors was quite incorrect! The tap also needed extra reading, after I had to calculate the different number of turns from the original T68-2 to us a T50-2 instead. I had to unwind and add a tap six turns from the grounded end, worked it out in the end. Its stable enough once warm, although it was sitting on the washing machine with the back door open with a gentle breeze. I need to find some polystyrene glue or "Q Dope", I believe its called, for gluing the inductor windings. Now to build the filter and find why the AF amp isn't working.


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