I found that on my OMNI VI + mod 3, I was easily able to hear a beat
note between the TCXO and the carrier of 10 MHz WWV.
I used Spectrogram to sort things out and make sure that I was beating
to the carrier and not one of the modulation tones.
It may be necessary to attenuate the WWV antenna input to make sure that
it does not overwhelm the TCXO signal.
When the tcxo is within less than 10 or 20 Hz you can see the beat on
the S meter.
This "feature" allows you to adjust the TCXO to within a fraction of a
cycle of WWV. One pulse per second is within 1 Hz of zero beat. 5
seconds per s meter cycle is within 0.2 Hz. This method is as good as
or better than using a counter and is limited only by the resolution to
the TCXO adjustment.
Only after making sure that the TCXO is accurate at 10 mHz. can you then
proceed to adjust the BFO frequencies. I was totally unsuccessful in
tuning the other oscillators and getting good audio on both sidebands
until after the TCXO was properly tuned. Once it is tuned, do not touch
it to compensate for errors in the BFO settings. This will just unravel
your good work.
I have a good HP counter but like the above method for tuning the TCXO
better.
Aloha,
John KH7T
|