Hi Ron,
Why not use logic?
If your logic is impeccable, yet built on incorrect premises, you can
make false conclusions.
For example, in most radios that have a digitally controlled VFO, with
memories, all of the oscillators in the rig are phase locked to a single
master oscillator. In that type of rig if you wanted to get the
frequency calibration just right, and if you have good strong reception
of WWV or WWVH on 10 MHz ( I'm using 10 MHz in this example, because it
is a frequency that the Omni VI can also tune to.) you could set your
VFO to 10.000.00, PBT to hear the beat between your BFO and WWV/WWVH
carrier, and adjust the master oscillator to get zero beat. No frequency
counter or other reference standard needed.
If you were to try this with the Omni VI, not realizing that the BFO is
a separate crystal oscillator, with several trimmer adjustments, you
could misalign the 20 MHz oscillator to compensate for an off frequency
BFO. Now after having made that mistake, if you have no way to directly
measure the BFO frequency, you would have a difficult time getting
things right. The information to avoid this mistake IS in the Omni VI
manual. Probably the best way to learn this detail would be to read the
BFO adjustment procedure. That procedure is in the circuit description
for the TX AUDIO BOARD. Not the first place a new owner of this radio
would think of looking for a frequency calibration adjustment. If you go
to the LOGIC BOARD description, it will tell you that the band select
crystal oscillators are lock to the 20 MHz oscillator. It does not make
any mention of the BFO, so it would be easy for a new owner to make the
mistake of adjusting the 20 MHz oscillator for zero beat of WWV on 10
MHz, only to find out later the BFO is off.
A step by step procedure could provide the necessary information all in
one place.
DE N6KB
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