Adjusting trimmer C10 will alter the TX frequency with respect to the
LSB receive frequency, which is dependent on the adjustment of C16. If
you go to the trouble of getting inside the Omni VI to adjust the BFO, I
suggest you check all of the BFO frequencies. There are five BFO
frequencies that must all be correct in order for the rig to work the
way it should. There are two crystals and five trimmer capacitors used
in the BFO. If you do not intend to ever use "real" FSK TX (using the
FSK keying input, not using audio tones in SSB mode) then only three of
these BFO frequencies are important to you. There is some interaction
between the adjustments of the trimmer capacitors, so it is best to
adjust them in the sequence described in the manual, and then recheck
and readjust as necessary to get them right.
The sequence is C10 for 9.000400 MHz in TUNE or CW TX mode, then C16
for 9.000000 MHz in LSB (or CW) RX. If you only operate CW and LSB you
can stop there, or if you want to use USB the next adjustment is C12 for
9.003000 MHz in USB RX.
Adjusting C16 only, without making sure C10 is adjusted correctly, could
achieve CW TX equal to CW RX when the received note is zero beat with
the sidetone, however the frequency displayed for both TX and RX could
both be equally wrong. Even if you do get the BFO adjustments right, the
displayed frequency still depends on the master reference oscillator on
the Logic Board.
DE N6KB
Fraser Robertson wrote:
I sent this info earlier but it seems to have disappeared. To fix the
TX/RX netting/tracking on CW you need to adjust trimmer C16, on the
corner of the TX Audio Board. This alters the CW TX freq. w.r.t. the
RX freq.
73 Fraser G4BJM
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