When a PLL is locked the VCO is operating at a frequency with an exact
fractional relation to a reference oscillator. There is always a minimum
frequency step size, which is dependent on the frequency divisions
(always integers) available. The only way to get frequencies in between
the minimum steps is to "warp" the reference a bit. If two PLLs use the
same reference, and have different step sizes due to different dividing
schemes, then warping the reference will move them both. There will only
be certain discrete frequencies where both can be really locked to
exactly the same frequency. Maybe that is good enough for some form of
diversity reception.
In the K3, the two receivers are electrically identical, except perhaps
differences in the IF filters installed.
DE N6KB
I have never encontered a condition with both rx on same
freq, not to say it could not happen if both were general coverage . But I
think it has to do with mathematical resolution limits in the two
synthesizers . They are "phase locked" in that both start from the same TCXO
but the schemes are different.
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