[Elecraft] Auto-spot, tuning aids, and the arcane history of CW pitch-matching

[ab2tc]

Hi all,

Agreed; the problem can easily be solved in analog radios without frequency
synthesis by offsetting the BFO frequency by those 700Hz or so in transmit.
In down conversion machines with a single IF in the 8-9MHz range that could
easily be done by pulling the BFO crystal. The Drake TR4 undoubtedly worked
this way. I bought my first transceiver in 1969 (I think), a Yaesu FT-200, I
think it was called in the US. In Europe it was sold as Sommerkamp FT-250.
As the Drake TR4 it was down conversion with a single 9MHz IF and worked CW
by pulling the BFO crystal into the passband of the 9MHz crystal filter on
transmit.

Another technical solution, which was used in the Collins KWM2 (and probably
KWM1) was to keep the balanced (de)modulator balanced and inject an audio
tone into it on transmit. Clearly the spectral purity of the CW signal would
be less than ideal in this case, but I am not sure if FCC type approval was
needed in those days. Nor am I sure what the the FCC spec for "inband" (read
close in) spurs would be.

AB2TC - Knut 


n0uk wrote
> The transceive problem didn't seem to exist on any older non-synthesized
> transceiver that I have used, including FT-101 series, TS-520/820 and
> later, KW Electronics KW-2000E.  these were all '70s era transceivers.
> 
> 
> 
> --
> 73 Chris Cox, N0UK, G4JEC

> chrisc@

> 
> _
> <snip>





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