Posted by
wayne burdick on
Jul 16, 2005; 6:21pm
URL: http://elecraft.85.s1.nabble.com/K2-birdie-at-28-265-MHz-tp380371p380373.html
The (-) voltage generator (oscillator) in both the KIO2 or KPA100
generates a couple of weak birdies. They will move around a bit from K2
to K2, because the birdies are the result of high harmonics of this
crystal oscillator mixing with high harmonics of the K2's VCO, and the
fundamental crystal frequency has a tolerance of about +/- 0.5 kHz.
We attempted to position the birdies in obscure parts of the spectrum.
If the 10-meter birdie happens to hit close to a beacon that you want
to monitor (28.265 is in the beacon area of the band), you should be
able to move it a bit by changing one capacitor in the crystal
oscillator. In the KIO2 case, the best choice would be C14. It is
normally 56 pF, but paralleling another 10 pF across it should shift
the oscillator a kHz or two, enough to move the signal off a CW beacon.
The value of C14 isn't critical; it could change +/- 20% without
significantly affecting output of the oscillator.
73,
Wayne
N6KR
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