[time-nuts] HP 5061A problem

wje wje at quackers.net
Mon Aug 18 21:14:29 EDT 2008

Possibly, but from what I remember, the real issue is erosion of the EM 
dynode surfaces from the high level of ion bombarment, resulting in 
reduced output and lower S/N, and eventually such low multiplication 
that the tube is considered 'failed'.

Bill Ezell
They said 'Windows or better'
so I used Linux.

wa1zms at att.net wrote:
> Per the last statement in the message below:
> "The danger running without a working ion pump, though, is that at 
> eventually you'll damage the electron multiplier."
> Is it correct to presume then that the EM becomes covered in
> "cesium splatter" and thus the S/N output gets poor?
> -Brian, WA1ZMS
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of wje
> Sent: Monday, August 18, 2008 1:43 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP 5061A problem
> If you install the second unit, your 5061A still won't work. +20v at the 
> sensor output will signal the ion current monitor to shut down the 
> electron multiplier supply.
> If you have some high-value resistors around, can you make up a test 
> 200M resistor string? If so, see what happens when that's connected 
> across 4 & 5 of the first 3500 v supply.
> However, even with the failure case you describe with the first unit, 
> I'd expect your 5061A to still work at least for a short time. Do you 
> have beam current? If not, you might have other problems as well. Check 
> the voltage at A15 pin 4. You should have +18 v or so. If not, more 
> troubleshooting is in order.
> Bill Ezell
> ----------
> They said 'Windows or better'
> so I used Linux.
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