Gang,
I have two DATUM 9390-52054 Disciplined Oscillators that use a
Vectron International model 716Y2690 crystal oscillator module. One
of the two units is showing 10 kHz sidebands about 35 dB down from
the main 10 MHz carrier, and looking at them on my spectrum analyzer,
they appear to be modulated whereas the main 10 MHz signal looks
clean. The other unit is not showing these sidebands. Listening to
the sidebands I'm hearing what might be data.
I first became aware of this problem a week or so ago when using the
"defective" unit as the reference for my off-air frequency
measurement service (see: www.biwa.cc) It was diluting my precision,
so I suppose it is the same as phase noise. Anyway, I'm looking for
any application notes on this module and also wondering if anyone
else has experienced such problems.
I've swapped the power supply with the good unit and the problem
stays with the original defective unit. I'm thinking the real
problem may be filter or bootstrap filter caps on the defective
unit's circuit board. I really need to probe the control and supply
voltages going to the oscillator module to be sure they are clean.
I'm also looking for another oscillator module. I've got a call into
Vectron, but so far, no return call from them.
All suggestions are appreciated.
Thanks,
Burt, K6OQK
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
b...@att.net
www.biwa.cc
K6OQK
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