Burt, those old Vectrons can be tricky. I had a 100MHz unit in my DTS-2070 and it could not be adjusted to 100MHz anymore, it had out-aged its trim capacitor. I threw it away I think, and replaced it with something more modern. My initial point was that your trim cap problem is very similar to what the loop is experiencing on oscillators that have an EFC hysteresis. There is not a single vendor in the world that I know of that specifies this EFC hysterisis, and this and the retrace of the crystal over the first couple of hours are two extremely important parameters as they can cause significant errors in GPSDOs. bye, Said In a message dated 10/21/2014 15:10:09 Pacific Daylight Time, [email protected] writes:
Said, The DATUM 9390's I have came from the Sieko pager watch project that I was involved in back in the mid to late 90's. As I recall, even when the DATUM clocks were new we'd have to adjust the oscillators periodically to keep them within lock range. The center of the DAC was around 27000 and they'd wander about 10000 plus or minus. They'd sometimes wander out of lock at plus or minus about 15000 and one of us would have to make a trip to some transmitter site to re-set the clock and re-center the Vectron module. The adjustment was accessible through a hole in the back of the clock. As I recall, you could give the oscillator a half turn one way or the other without causing too much distress to the clock. This held true with my two units until the one oscillator developed the adjustment problem. Not knowing what was really inside the Vectron, I attributed the problem to a defective or cracked piston capacitor. The adjustment certainly had the feel of a piston capacitor. Since I made the modifications I described, the DAC sits within about 10 of 27450, and that's where my units are happy. By the way, I've got two 1.5 KVA UPS's in my shoppe, one for each clock. They'll run for a long time on those. Burt >From: Said Jackson <[email protected]> > >Subject: Re: [time-nuts] LTE-Lite module and the pendulum... > > >Burt, > >Great insight thanks. You nailed it: out with the old oscillator and >in with one that doesn't have that problem. > >Btw the mechanical tuning issue you mentioned is essentially the >same exact problem: even the slightest turn will make the frequency >jump too high or too low. It can drive you (and the loop) crazy >trying to get it on-frequency. > >Bye, >Said Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. [email protected] www.biwa.cc K6OQK _______________________________________________ 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.
