Thank you all for your help this afternoon. Good ideas. I better hope the crystal is good and just concentrate on the discrete.
I'll continue to investigate. The oscillator won't oscillate on its on, ....but if I 'force' a 10MHz signal either on the collector of Q3 or even touch the crystal oven with the 10MHx signal, ...it will oscillate and amplify and deliver a signal. Must be a cap or perhaps the inductor in the 10MHz circuit. -Don -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio Boriani Sent: Tuesday, December 20, 2011 3:01 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Efratom FRK - no 10Mhz oscillator 10MHz crystals used in OCXO are designed for the temperature of the oven so it is not possible to find an off-the-shelf suitable crystal. Better find a crystal coming from an OCXO. On Tue, Dec 20, 2011 at 7:10 PM, Peter Bell <bell.pe...@gmail.com> wrote: > 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 <dlewis6...@austin.rr.com> > 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 -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
