[time-nuts] HP105B Help

[Dave Miller]

Thanks Bob,
I  got some offline help from someone and I redid my setup and I am now
getting decent data. It looks like it was finger problems.
It has only been warming up for a day but it is now looking decent. Once I
get a longer plot I will post all the things I did wrong in my setup.
It was the first time I was measuring a 5Mhz source against the 10 MHz on
GPSDO. And I learned something important.

I got the HP105B for $300 so I think I got a decent deal. No battery
which is probably a good thing.
A couple of resistors and a couple of electrolytics.
The next step is to bring out the 10 Mhz to the back.
Open to suggestions on how best to do that.
I do recall recently someone  posted a buffer solution using a LH0033CG. I
did get some of those from Fleabay. I do recall there were some comments
that those parts were not a good choice.

Thanks everyone I am not off to the races and look at it closer.
Dave
VE7HR




On Sun, Dec 13, 2020 at 5:58 PM Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> The “better” 10811’s were sorted out from the “general population”. There
> is a
> lot of anecdotal evidence that (at least for phase noise) far more hit the
> better
> categories than got labeled as such.
>
> If indeed your device seems to have trouble, the OCXO is a likely
> candidate.
> The power supply can be checked with a DVM (and maybe a scope). The output
> amps can be checked by tapping directly in to the oscillator output. EFC
> issues
> can be tossed out by grounding the EFC.
>
> Given the eBay price ratio between the 105 and 10811 prices, the roundoff
> error
> in the 105 price pretty well covers a 10811 or three ….
>
> Bob
>
>
> > On Dec 13, 2020, at 7:38 PM, Dave Miller <ve7hr at ve7hr.ca> wrote:
> >
> > Thanks Bob,
> > No rust just a couple of electrolytics leaked taking out a couple of
> nearby
> > parts.
> > Everything else looks very nice.
> >
> > I might be able to find another 10811 to try. I thought there were
> > different versions
> > The specified one was supposed to be special low phase noise.
> > But I know nothing about this as I am a rookie.
> >
> > This is the setup as I forgot to post it in original post
> >
> > 5370B
> > TI
> > 1PPS from HP GPSDO to Arm
> > External arm
> > 10 MHZ form HP GPSDO to start
> > Stop is 5 MHz output from HP105B 5MHz
> > The ADEV is terrible
> > There is a sawtooth on the Original Phase difference linear residual that
> > seems very repeatable and may explain the apparent jitter of the output.
> >
> > Dave
> >
> >
> >
> > On Sun, Dec 13, 2020 at 4:31 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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> >>
> >>
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> >
> >
> > --
> > 72 de Dave
> > VE7HR
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-- 
72 de Dave
VE7HR