[time-nuts] HP 10811 40 Hz low.
kb8tq at n1k.org
Fri Dec 16 07:18:44 EST 2016
If it is a crystal, a broken seal on the can is a pretty good guess. Often this runs up
the resistance as well.
> On Dec 15, 2016, at 8:57 PM, paul swed <paulswedb at gmail.com> wrote:
> 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.
> On Wed, Dec 14, 2016 at 7:10 PM, Bob Camp <kb8tq at n1k.org> wrote:
>> Crystals do indeed fail. In the case of 40 Hz low, I’d look for a shorted
>> cap in series with the crystal.
>>> On Dec 14, 2016, at 5:23 PM, paul swed <paulswedb at gmail.com> 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
>>> It needs to be within a Hz. Checked everything feeding voltage and such
>>> 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
>>> 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
>>> 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
>>> hot happy.
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