[time-nuts] Re: HP 5061Bs on ebay

[Tom Knox]

There were also late model 5061Bs that used the compact tube, which was a modified 5071A tube, I.E. different harness and EPROMs.
I agree when looking at a used cesium standard one should assume it is near or at "end of life" but that said personally I found a surprising number of cesium standard that the tube was excellent and the issue was related to other issues, some minor as cap failures. But ultimately CBT life is about 4-6 years for a High-Performance CBT and 8-15 years for a standard CBT. So, for us Time-Nuts it is an expensive hobby.
Cheers;
Tom Knox
SR Test and Measurement Engineer
Phoenix Research
4870 Meredith Way Apt 102
Boulder, Co 80303
Formerly of:
357 Fox Lane
Superior Co 80027
303-554-0307
actast at hotmail.com

https://www.thedenverchannel.com/news/marshall-fire/superior-man-moving-forward-after-losing-dream-research-lab-during-marshall-fire

"Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein
________________________________
From: Bob Camp via time-nuts <time-nuts at lists.febo.com>
Sent: Wednesday, June 14, 2023 8:14 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Cc: Ke-Fong Lin <anotherlin at gmail.com>; Bob Camp <kb8tq at n1k.org>
Subject: [time-nuts] Re: HP 5061Bs on ebay

Hi

There are a *lot* of 5061 chassis running around. There are *very* few working
tubes to go with those chassis.  The tubes wear out, but the chassis gets kept
“just in case”.

It is not unusual to buy a half dozen or more in order to find one with a tube that
“kinda sorta” works. Many of the ones that do get running are not very close to
their original spec performance. (The stability of the unit degrades as the tube
wears out …..)

For a while FEI had a contract to supply replacement tubes to the US government.
You will find those tubes in some units. You also will find units with tubes out of other
brands of Cs standards. How well those work is a bit of a “that depends” sort of thing.

None of this is to say “don’t do this”. It only is a caution that the route from having
nothing to having a good performance unit may be pretty long. You might get lucky
early on …..

Bob

> On Jun 14, 2023, at 6:09 PM, Ke-Fong Lin via time-nuts <time-nuts at lists.febo.com> wrote:
>
> Hi everyone,
>
> So unfortunately, no, I won't be able to buy the newly introduced
> 5071B (or rather revamped 5071A) :)
>
> However, and you probably know already, there's a few 5061Bs from one
> particular seller.
> They're pretty tempting, and I'm considering making an offer.
>
> They seem to be later models (late 80s), and some of them even have
> "tube good" or "tube ok" sticker on them.
> Some are missing bits and pieces (like HV supplies) but with the
> cesium tube. And it seems that parts other than the cesium tube, are
> easy to find (lots of 5061 with dead tubes to scavange from).
> A few seem even customized, perhaps by Frequency Electronics? For
> internal use? Seems that they've added some monitoring circuitry.
>
> Any comment, especially on the tubes, their remaining life or lack thereof?
> Still a project, but that's really something I start considering.
>
> Best regards,
>
> --
> /* Lin Ke-Fong
> * anotherlin at gmail.com
> * I always do what I say, especially if it's something stupid.
> */
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