Dear LF group,
If you have an RA1792 RX, and require and accurate audio
frequency (for calibrating a sound card for "Wolf" reception for
instance), you can get one very easily by tuning the RX to 0Hz in
CW mode. This makes the LO equal to the IF frequency, and some
signal leaks through the mixer into the IF, where it is demodulated
as a CW tone. The audio frequency output is then equal to the
BFO offset, which can be set in 10Hz steps from 0 to 8kHz, as I
recall. The frequency accuracy will be that of the internal
reference, ie. 0.1ppm if it has been calibrated fairly recently.
This might well work in other receivers with synthesised BFOs
which can be tuned to zero too.
Cheers, Jim Moritz
73 de M0BMU