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My BITX20 rig
Hans Summers <Hans.Summers@...>
My BITX20 is at an advanced stage of construction, but due to family
commitments I won't have very much time to finish it off over the next few
I used a modular construction style, each stage of the transceiver is
constructed on a 2 x 1 inch (approx 50 x 25mm) of PCB stock in the "ugly"
style with no PCB etching. The modules are mounted at right angles to the
"chassis" which is also made from single-sided PCB. I have used tap washers
like the original, except for the transformers which are 15 turns
bifilar/trifilar on FT37-43.
The VFO works fine, I'm using an old variable capacitor and I removed 20
turns from the 150 turn coil to get the frequency range right. I noticed the
fine tune is rather non linear with voltage, and also much more effective at
the low end of the frequency range than the top. Something to investigate
I'm using one of my simple 2-chip frequency counters with 8 LED binary
readout of the frequency offset in 0 - 100KHz, 0.5KHz resolution. The cost
of this module is just UK £2. See my counter page
http://www.hanssummers.com/radio/sfreq/index.htm for details (the Mk1 is in
I have some photographs for you but it'll take me a while to sort them out
as I'm rather busy right now. Hopefully sometime next week I'll have them
72/3 de Hans G0UPL