On Sun, 2006-07-09 at 09:30 -0400, Bwana Bob wrote:
> It should be possible. I've been thinking about it myself. It should be
> easy to modify the bandpass filter and change the crystal. We need to do
> the math to make sure there will be no spurious outputs. My concern
> would be the second harmonic of the PTO which operates at 2.2-2.7 MHz
> getting into the output, though there is a low pass filter on the PTO
While a low pass filter on the PTO output will keep it clean going into
thee mixer, most mixers create considerable harmonic internally.
> Other than that, it should be possible to modify a 40 meter band module,
> but where can we get band modules? I don't think Ten Tec has any more.
It may be necessary to go away from direct frequency read out to move
PTO harmonics away from the 60 meter channels so as to reduce
interference on receive, but it may not be possible to move them far
enough to not have spurs transmitted. For a long time there was the same
concern for the Collins S-line and KWM-2 in the 5 MHz region because of
second harmonic of the PTO (2.5 to 2.7 MHz.). But its been proven to not
be a problem and more recent manuals allow such operation.
> Bob WB2VUF
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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