[time-nuts] Re: HP 5065A, no 2nd harmonic.

[Bob kb8tq]

Hi

The last time I went 10811 shopping, I found a seller with a lot of them. 
His price was right ($40 each) if you bought a batch at a time. I tested
them all for ADEV / phase noise and the other basic bench stuff. I did 
not run any of them over temperature ( but neither did HP …. ). 

Net result was about 5% that had some significant issue ( = you could 
not use them in a counter). Maybe another 20% had phase noise or 
ADEV that was in spec, but not that great. The balance ranged from pretty
good down a few with high parts in 10^-13 for ADEV. 

The real issue is finding a group that has not already been sorted. There
are folks who run through and do the same sort of testing. The worst 
1/3 of the group then goes back on eBay …. (including the ones with
significant issues). 

Bob

> On Dec 1, 2021, at 9:11 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> And I will bet the smell is as bad as the larger 0106 oven. As I say its in
> a sealed bag and not sure how I will recover it. Need the windows open.
> The suggestion of buying a replacement is the best even if you do need to
> buy 2-3 to locate a good one.
> Regards
> Paul
> 
> On Wed, Dec 1, 2021 at 6:13 AM Askild <megafluffy at gmail.com> wrote:
> 
>> Hi,
>> 
>> Just a little warning.
>> Included are some pictures of a 10811 where thermal fuse protection have
>> not functioned.
>> I do not know why, if the fuse did not work, or somebody replaced it with a
>> wire, as this was in a HP 8663A that I found in a recycling bin, and I do
>> not know the history.
>> 
>> 
>> Regards,
>> Askild
>> 
>> 
>> 
>> On Tue, Nov 30, 2021 at 8:34 PM Bob kb8tq <kb8tq at n1k.org> wrote:
>> 
>>> Hi
>>> 
>>> The thermal fuses die on their own far more often than they die
>> protecting
>>> anything. The fuse is there to provide safety is certain odd situations.
>>> The
>>> simple answer these days is to replace it with a piece of wire.
>>> 
>>> Bob
>>> 
>>>> On Nov 30, 2021, at 12:05 PM, Larry McDavid <lmcdavid at lmceng.com>
>> wrote:
>>>> 
>>>> Do these thermal fuses fail spontaneously or is there a common cause?
>>>> 
>>>> If the "heater" transistor mounting screws were quite loose, those
>>> transistors themselves might have overheated and failed. But, a thermal
>>> fuse should fail by high temperature...
>>>> 
>>>> Sounds like progress, though. Cold OCXO means low frequency.
>>>> 
>>>> Jared, I sent you a private email with some pictures; did you get that?
>>>> 
>>>> Larry
>>>> 
>>>> 
>>>> On 11/30/2021 8:03 AM, Jared Cabot via time-nuts wrote:
>>>>> Well, I found it, the thermal fuse is open circuit.
>>>>> If I briefly bypass it with a jumper wire, the oven pulls the expected
>>> current.
>>>>> Looks like I need something that will trip at roughly around 115C,
>>> rated to 1.0A
>>>>> (HP Part number 10811-80008)
>>>>> Hopefully I can find something in Akihabara to make it easier to get
>> my
>>> hands on ASAP...
>>>>> Jared
>>>> ...
>>>> --
>>>> Best wishes,
>>>> 
>>>> Larry McDavid W6FUB
>>>> Anaheim, California (SE of Los Angeles, near Disneyland)
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