[time-nuts] Efratom FRK - no 10Mhz oscillator
dlewis6767 at austin.rr.com
Tue Dec 20 12:29:13 EST 2011
A little help, pls, from the more experienced. This is my first time into
one of these .I have listened and learned from you' all for some time,
though. It can be intimidating in this close-packed FRK.
I am trying to bring up an Efratom FRK I have had for a while.
The 10 MHz oscillator does not start upon power on.
Any ideas where to look?
I have done the following:
* I have it opened-up and applied 24vDC and the current starts up
initially at 1.45 amp and slowly goes down to ~.6- .8 amps.
* Since I have no 10 MHz output, .so I looked at the oscillator board
and nothing out from it.
* The 17 volt dc supply-rail is good, and the VCO input signal to the
varacter control-circuitry is constantly ramping up and down slowly between
~1volt and ~15 volts.
* All the transistors in the oscillator circuit seem ok with a VOM,
..and when I purposely inject a 10Mhz signal into the collector of the
'oscillator' transistor (Q3), .I do get a clean 10Mhz out of the unit (of
course it won't lock), .and I haven't even been into the rest of the unit.
* I think the crystal is bad, .I took the cover off the crystal oven,
it 'looks' ok, . and the crystal heater in the oven is heating and
Any ideas? .does the 10 MHz crystal in these have a history of failing?
Can I get a replacement crystal for it easily?
How can I test this crystal for pass/fail?
Thanks, .just my first test of the waters as a fledging time-nut.
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