[time-nuts] HP10811 Oscillator Thermal Fuse

Bob kb8tq kb8tq at n1k.org
Thu May 11 19:51:44 EDT 2017


The ones that people decided are dead quite literally went into the trash can long long
ago. They never made it into the eBay era. The warranty on the gear was short enough
that nobody thought to send them back. The days of “tear into it and fix it” at the component
level were over *long* before the 10811 came out. Anybody servicing this gear was on
a strict “sway modules and get it running” set of orders. 


> On May 11, 2017, at 7:42 PM, Donald E. Pauly <trojancowboy at gmail.com> wrote:
> https://www.febo.com/pipermail/time-nuts/2017-May/date.html
> These oscillators sold for $800 in 1985 or so.  They are on eBay all
> working for $250 or more.  Where are all the ones with blown thermal
> fuses for $25?  I want to buy.  It would be interesting to have the HP
> warranty data for nuisance blows.  The three reported fire preventions
> would have paid for the labor on all of the reported nuisance blows.
> This is not to excuse the HP design error of picking a thermal fuse
> temperature too close to the operating temperature.  Smoke damage
> could do thousands of dollars of damage to a HP5061B or and expensive
> microwave instrument.
> πθ°μΩω±√·Γλ
> ---------- Forwarded message ----------
> From: Bob kb8tq <kb8tq at n1k.org>
> Date: Thu, May 11, 2017 at 4:28 PM
> Subject: Re: [time-nuts] HP10811 Oscillator Thermal Fuse
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Hi
> A bit in jest:… that compares to 3,957 incidences of open fuses that
> had nothing to do with
> a thermal runaway. Of those, the majority 3,721 resulted in the 10811
> being tossed
> in the garbage as “another junker”……(yes, those are estimates, but I’d
> bet they are close
> based on the number of 10811’s made and how flakey those fuses are).
> Bob
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