[time-nuts] HP105B Help

[Bob kb8tq]

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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> 
> 
> -- 
> 72 de Dave
> VE7HR
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