[time-nuts] HP5061B Beam Tubes

John Miles john at miles.io
Mon Sep 23 17:43:49 EDT 2013


I've always wanted to try baking the entire tube to vaporize any
accumulations of Cs metal outside the internal oven.  Is that what you did,
Paul?  If some of the free cesium metal near the detector can be recondensed
at the oven end, or just redistributed uniformly throughout the tube, it
might render a noisy tube usable again.

The point at which cesium vaporizes is 250C / 482F, and that seems like it
could be survivable unless there are thermoplastic structures or insulation
sleeves inside the tube for some reason.  The operation might be tricky,
because while you wouldn't want to heat the tube sufficiently to vaporize
all of the remaining cesium in the internal oven, you would also need to
bake the tube for quite some time to heat its internal structures uniformly,
since it's basically a vacuum bottle.  Outgassing from various internal
materials and structures would also be a concern.  Something to try with a
tube that is otherwise ready for the scrap heap...

-- john, KE5FX
Miles Design LLC

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-
> bounces at febo.com] On Behalf Of paul swed
> Sent: Monday, September 23, 2013 12:52 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP5061B Beam Tubes
> 
> Tom
> I added 10 degrees and used the built in temp sensor in the tube as a
> gauge. So its sort of accurate to say 10 degrees. I remember evaluating
the
> temp several ways.
> I did not return it to original temp as I believed at the time I was
baking
> out the last few Cs.
> What your saying in the threads very interesting. But don't have time to
go
> back and adjust or reconnect the old oven controller. I would have to look
> at all of that again to see whats needed. I did this about 2 years ago its
> in the time nuts archive I suspect.
> Regards
> Paul.



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