[time-nuts] Bad batch of HP10811's

John Miles jmiles at pop.net
Tue Jan 16 23:22:43 UTC 2007


Powers down after how long?  The oven current should drop dramatically in a
few minutes.  Does it quit oscillating?

Doesn't sound like the thermal fuse, if it stops oscillating altogether.

-- john, KE5FX

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Jason Rabel
Sent: Tuesday, January 16, 2007 3:15 PM
To: richard at karlquist.com; 'Discussion of precise time and frequency
measurement'
Subject: Re: [time-nuts] Bad batch of HP10811's


Here's one for you guys...

What would the cause be when you power one up, and it seems to try to
oscillate, but then powers down (current consumption drops way down)?

Thermal fuse again or just toast?

Jason


> I'll apolgize on behalf of HP for putting in that stupid thermal
> fuse.  It cannot be soldered in for the obvious reason that the
> soldering temperature exceeds the fusing temperature.  Therefore,
> it must be socketed.  It does NOT have gold plated leads, and
> hence the reliability of the contact with the socket is poor.
> I think the reason for it was that if the oven ran away, the
> thermal foam would burn up and out-gas toxic fumes.  Ovens very
> rarely run away.
>
> The unit that is 500 Hz off is not due to a cold oven.  There isn't
> that much tempco in the crystal.
>
> Rick Karlquist N6RK





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