[time-nuts] HP105B Help

[Dana Whitlow]

If you're thinking it's the 10811, here's something to try:

Arrange to measure output frequency, and tune voltage, and put the curves up
on a dual-trace o'scope.  If the output frequency fluctuations correlate in
the
correct direction of the tune voltage fluctuations, then the problem is
probably
not in the 10811.  But if the tune voltage appears to be fighting the output
frequency variations, then it's most likely to be the 10811 (or perhaps
just its
power supply source) who's at fault.

Dana


On Sun, Dec 13, 2020 at 6:31 PM Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> If the inside of the 105 went under water long enough to rust out a lot
> of parts on the boards, it’s a good bet that the 10811 in the unit got
> hit pretty hard as well.
>
> Simple answer: Spend $40 on an eBay replacement for the 10811.
> It should just plug in ….
>
> Bob
>
> > On Dec 13, 2020, at 5:15 PM, Dave Miller <ve7hr at ve7hr.ca> wrote:
> >
> > I am in the middle of resurrecting a HP105B, It is one of the later
> models
> > with an 10811 in.
> >
> > I have fixed the obvious issues like the electrolytics that were missing
> > and other parts that had leads evaporated due to corrosion.
> >
> > The basics seem to work, A not bad looking sine wave etc.
> > But the ADEV numbers are terrible.
> > I am going back to make sure it's not a measurement setup issue. That is
> > good. Just tested another OCXO and the test setup is good.
> > Attached in a link to a .tim file
> > https://www.dropbox.com/s/zebwiqy913v7k0k/HP105B%20test.tim?dl=0
> > I am hoping one of the more knowledgeable folks might suggest where to
> > start looking.
> > I have checked all the other electrolytics and the ESR and capacitance
> > looks good. I think the power supply seemed clean.
> >
> > I have taken out the easy to get boards and cleaned card edges etc but
> this
> > persists.
> >
> > The saw tooth on the original phase is yelling something at me but I
> > don't have a clue.
> >
> > Thanks
> > Dave
> >
> > --
> > 72 de Dave
> > VE7HR
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