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

[paul swed]

Totally agree with the comments its a real gamble. Even if it says the tube
works what does that mean? The beams high enough to lock. I can tell you
the beam can be unreadable and the system will lock. I have a 5061 unit
with 0 beam and the metering circuit is not bad.
That gets to Bobs comments well its locked but how good. The noise is
higher and the stability is noisey. It can be seen using a good reference
and a scope. But on average it tends to stay put.
The unfortunate reality is the asking price is something but at 60 LBs the
shipping is expensive.
By all means go for it. It has been a great education for me at least
working with the 5061s and FTS.
But go in eyes wide open.
Good luck to you.
Paul
WB8TSL

On Thu, Jun 15, 2023 at 1:44 AM Bob Camp via time-nuts <
time-nuts at lists.febo.com> wrote:

> 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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