[R-390] Frequency Synthesis on the R-390/A using the SBM-1102

[Tisha Hayes]

I ran across a document explaining the setup of the FFR-41 and how the
SBM-1102 would provide precision frequency synthesis to a pair of R-390A's.
(document MM03276).

It appears that the connections to the receivers would be to the 1st mixer
with an external 17 MHz reference, the 2nd mixer with an external 9-17 MHz
reference and to the VFO with an external 2.455 - 3.455 MHz oscillator.

All of it is locked to a single 1 MHz crystal and there are provisions to
support the CV-1597 sideband converter for receiver tuning.

It is a neat idea and I can see the application for diversity reception of
RTTY where the receivers would have a single frequency reference.

This looks sort of 1967'ish and knowing that many list subscribers were in
far away, hot, sticky environments at the time I wonder if anyone had
experience with this lashup. I would think that the R-390A's would require
some modification (additional jacks and cabling) to bring the 1st and 2nd
mixers and the VFO connections to the back panel. Has anyone seen a rig
modified in this manner?

I know that NASA (and probably NoSuchAgency) had R-390A's modified so they
could adjust for doppler shift from space vehicles. This was also done with
an external reference and the R-390A was rebranded as a different model.

-- 
Ms. Tisha Hayes

----------------
"I will not recant the truth. I am corn, not chaff; I will not be blown away
with the wind or burst by the flail. I will survive both."
-Walter Milne, 1558