[time-nuts] HP 10811 update

paul swed paulswedb at gmail.com
Fri Jul 26 12:47:35 EDT 2013


sounds like time to add a R across the temp set R. That will lower the R
and raise the temp. Its also easy to actually do.
Thanks


On Fri, Jul 26, 2013 at 12:08 PM, Bob Camp <lists at rtty.us> wrote:

> 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 <paulswedb at gmail.com> 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 <lists at rtty.us> 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 <paulswedb at gmail.com> 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
> >>> <stefan_heinzmann at gmx.de>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
> >>>>
> >>>>
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