Hi If it is a crystal, a broken seal on the can is a pretty good guess. Often this runs up the resistance as well.
Bob > On Dec 15, 2016, at 8:57 PM, paul swed <[email protected]> wrote: > > Bob > Took your advise and did check all of the caps in teh oscillator along with > resistors. All are as they should be. Though they do differ from the > schematic I have for the HP 10811. But thats normal reality on HP stuff. So > it is a sick 10811. > So at this stage I have jacked a external 10 MHz reference into teh system > to replace it and the rest of the Z3801 seems to be working. It needs more > time but did acquire satellites. It hasn't locked yet and unsure it can > with an external reference unless I use the TBOLT 10 MHz. Kind of liking > that idea. > Since the oscillator was bad and thats how I received it several years ago > the DAC is at 99.99% full scale because it was 40 Hz low. Want to reset > that to mid range. > Also I speculate the actual gps receiver is down on sensitivity but I do > have replacements. > Regards > Paul. > > On Wed, Dec 14, 2016 at 7:10 PM, Bob Camp <[email protected]> wrote: > >> Hi >> >> Crystals do indeed fail. In the case of 40 Hz low, I’d look for a shorted >> cap in series with the crystal. >> >> Bob >> >>> On Dec 14, 2016, at 5:23 PM, paul swed <[email protected]> wrote: >>> >>> I have a hp z3801 that is spare parts it never worked correctly. Did some >>> digging and at least one major issue is the actually HP 10811 is 38 Hz >> low. >>> It needs to be within a Hz. Checked everything feeding voltage and such >> and >>> they are solid at 5.7V from the regulator. The varicap works as expected. >>> Signal levels out are clean and correct. Temp is about 82C also inline. >>> The oscillator is actually fairly simple. Do xtals just fail after many >>> years? >>> May see if I can map a Piezo oven oscillator into the z3801 just to see >>> what if anything happens. Now that I know the warm oven signal drops >> fromm >>> 22V to 3.8V when hot. Fake it out. >>> Not sure the outer oven actually matters on the z3801. But even that can >>> actually be hooked up to make any circuit that might want to know thats >> it >>> hot happy. >>> Regards >>> Paul >>> WB8TSL >>> _______________________________________________ >>> 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. >> > _______________________________________________ > 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.
