Perry,
Marv W6OQI and Stu K6YAZ and I looked at ways to either stabilize the
Product Detector's L.O or devise a scheme to derive the necessary
L.O. frequencies from the reference. Short of creating a monster of
a science project, there's no simple way to get there. Stu made a
comment that there's nothing sacred about the 1850 Hz tone. You
could change the L.O. to produce any tone within the systems (audio)
bandpass and have it work - as long as you know what the offset is
that results from the "new" tone and apply that to your
calculations. If that's all you wanted to use the receiver for that
would be ok.
The downside of that is that the reproduced audio would contain an
error, much like a SSB receiver that is improperly tuned. Remember
that the L.O. is replacing the carrier that would normally be present
in AM signal. It needs to be at precisely the right place relative
to the sidebands in order for the demodulated audio to be
correct. Even a small amount of error, one that would not be obvious
to the ear but could produce a sizable amount of error for this
groups demands for accuracy.
For me the HP-3586B is a tool, a wonderful tool.
For the present I plan on using the measurement technique that Burt
Weiner K6OQK so graciously shared on the net and to us on the
list. Locking my 3586 and 3336 to my GPSDO should allow me to get
good results. I also can compare my first GPSDO to a second
redundant GPDSO. This I can understand and do.
Regards,
Perrier
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
[email protected]
www.biwa.cc
K6OQK
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