Hi HP spec'd the crystals to be at a < 1x10^-8 / C slope at the marked temperature on the crystal. The center of the curve should be in the vicinity of 90C.
You are ~ -4.5 x 10^-6 low, so that would be > 10 C away from that point going cold and a bit further going hot. Since the oven is at ~80C, it's not to hot… Bob On Jul 26, 2013, at 10:09 AM, paul swed <[email protected]> wrote: > Good comments. Indeed I will order up a new xtal from digi-key. They should > be in stock any day now. I do agree with the comment on the cap in > parallel. I had not thought about the series cap dropping and there is a > .1uf as I recall. Need to look. The varicap seems to work very well so > don't believe thats an issue. > Will do some more hunting. > By the way as a heads up the top and bottom cover of the xtal compartment > are actually a pain to screw back together. > Anyone have a sense of the Hz change per degree C? > Thanks > > > On Fri, Jul 26, 2013 at 8:52 AM, Bob Camp <[email protected]> wrote: > >> Hi >> >> Ok, since it's moved *down* and it's about on temperature there are a >> couple of likely possibilities: >> >> 1) The crystal leaks and there's air in it >> 2) The trap coil(s) / capacitor(s) have changed value >> 3) The varicap is shorted / forward biased >> >> Normal factory troubleshoot (after checking the varicap) would be to swap >> the crystal and see if the problem follows the crystal or the oscillator. >> Yes, I know, that's not very helpful in this case - sorry about that. >> >> Bob >> >> On Jul 25, 2013, at 9:32 PM, paul swed <[email protected]> wrote: >> >>> Well lucks not so good do have the voltage closer but as Bob C said. That >>> ain't the issue. >>> Darn I hate when he is right. By the way the oscillator draws 26 ma >> approx >>> as a reference. Reassembled everything and let the oven heat up it >> settles >>> at 81C 15 min after start and within a respectable range of the temps >>> listed in the service manual. Measured with a K thermocouple. Freq is at >>> 9.999955. or 45 Hz low >>> Tuning the variable cap has 20 Hz range and the cap was pretty much >> center >>> range. Have not played with the varicap but that should have a very small >>> effect. >>> I can easily adjust the temp setting R to raise the xtal temp. But that >>> seems like a jerry rig. >>> Could a xtal of this quality simply go bad over time? >>> Somewhat at a loss here. >>> I have a spare 10544 (Would not use the z3801 outer oven)and wonder if at >>> least I could use that with the Z3801. Anyone know if the efc would work? >>> Regards >>> Paul >>> WB8TSL >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> On Thu, Jul 25, 2013 at 10:28 AM, Stefan Heinzmann >>> <[email protected]>wrote: >>> >>>> paul swed wrote: >>>> >>>>> I can't believe you found the transistor. When I pulled it out last >> night, >>>>> its actually a MPSA18!!! I had not had time to look it up but figured >> it >>>>> was a ebay leftover hunt. :-) >>>>> At that price I may order 20 of them. Like the gain. >>>>> >>>>> Toshiba used to make a transistor with even higher gain, the >>>> 2SC3112/2SC3113/2SC3295/**2SC4666 (same chip, different package). They >>>> discontinued it recently, however. >>>> >>>> Cheers >>>> Stefan >>>> >>>> >>>> ______________________________**_________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to https://www.febo.com/cgi-bin/** >>>> mailman/listinfo/time-nuts< >> 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. _______________________________________________ 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.
