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

[Bob kb8tq]

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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