[time-nuts] Maximizing Cs Tube Life

[John Miles]

You're right, at 11 ua, that 5071A is pretty much hosed.  I'd be surprised
if it knows what day it is.  You'd better cut your losses and send it to me
before it gets any worse.  Cesium is a hazardous material, not that there's
much left in this particular unit, and you don't want to be stuck having to
throw anything away that contains it.  There's all sorts of red tape, up to
and including EPA fines and prison time.  That said, I could reimburse the
cost of shipping, to defray the inevitable expenses associated with
disposal.  Do you take PayPal?

Seriously, the manual says 0-40 uA is the 'typical' range, so I wouldn't be
inclined to worry about it.  It could be an artifact of the high-performance
tube, for that matter.  You might open the unit up and measure the current
yourself, to make sure the monitoring circuit isn't lying to you for some
reason.

Looks like pages 68 and 127-129 of the service manual .pdf cover ion-pump
supply verification.  Have you tried those procedures yet?

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of aceamusements at mchsi.com
> Sent: Friday, July 10, 2009 7:58 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Maximizing Cs Tube Life
>
>
>
>
>  I have a similar question I have 2 hp 5071a and I purchased one
> new in the box never opened and one used.both have been in
> operation over a year, the new one high perf tube new style tube
> US4240 started out in storage for two years before I plugged it
> in for the first time..the pump went right down to .2 -.4ua as
> normal but as time has gone by it has risen (lineraly) to almost
> 11.0uA (I think this may not be good). the elect mult volts on
> this tube started out about 1500 and droped within 6 months to
> 1150 and has stayed there.
>
> my other used unit has a pump current of 0.0 or 0.2 all the time
> and a mult of 1430 (stays steady also)been like that for months
> but the new unit continues to rise(pump current).have tried
> turning off the cs oven and leaving on the pump but with no avil
> is this new tube heading twd an early death?
>