Hi, Don It's been quite a while since I worked on a FRK, but from what I remember the only signals going to that oscillator board are power and the control voltage. It might be worth checking the control voltage to see if it's at a plausible value (nominal is 5V, spec range is 1V-16V, IIRC) - if you have a spare xtal around, just try connecting it to the pins on the PCB and see if it starts up.
I'm not aware of the xtals being failure prone - I have seen one FRK with a bad one, but having seen the condition of the system it was removed from, that was clearly impact damage. Regards, Pete On Wed, Dec 21, 2011 at 1:29 AM, Don Lewis <[email protected]> wrote: > 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 > regulating. > > > > > > 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. > > > > Don Lewis > > Austin, TX > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
