[time-nuts] Re: 5061A HV Supply, et al. {External}

[Jim Muehlberg]

Rodger,

Thanks for the encouragement!  I'm trying not to spend too much effort 
on this - sort of a distraction from real work.  One would think that 
NRAO would have a HV power supply lying around somewhere, but astronomy 
has gone solid state now for decades!  We have a grad student trying to 
nurse along another 5061 and we'd like to have a pair. I guess I'll 
slice open the A18 module and see what makes it tick.

Thanks again,

Jim

On 11/10/2022 9:11 AM, Rodger via time-nuts wrote:
> Hey Jim,
>
> I got a 5061a a couple years ago with high ION pump current.  In my case the 3500 volts was there but the tube was not pumping down, even after being on for weeks.  I found a Terranova 741 Ion pump power supply on eBay for under $100.  It was listed as not working but worked AOK when I got it.  It's a nice supply with variable output voltage, current limiting, safety interlocks, etc.  I hooked it up to the tube and let it run for a few weeks.  Tube pumped down successfully and is working AOK now.  My guess is that my A18 wasn't capable of supplying the current needed to pump down the tube but the external power supply was.
>
> Note: I proceeded very carefully with the external supply, letting it run for days at lower voltages and gradually working up to 3500.  Also, I kept the current limit set as low as it would go.  Anyway, it worked for me.  Good luck with yours.
>
> Rodger
>
> -----Original Message-----
> From: Jim Muehlberg via time-nuts <time-nuts at lists.febo.com>
> Sent: Wednesday, November 9, 2022 11:07 AM
> To: time-nuts at lists.febo.com
> Cc: Jim Muehlberg <jmuehlbe at nrao.edu>
> Subject: [time-nuts] 5061A HV Supply, et al.
>
> I've recently come into possession of a 5061A.  It is claimed that the tube is exhausted, but I'm unwilling to scrap it (horrors!) yet.  I'm not well equipped for HV measurements, but it appears the +3500 V supply is not working.  So, I'm hoping the tube just needs to be pumped since it hasn't been powered for years.  Also missing the A3 assembly, but I'll worry about that later...
>
> Anyone willing to part with their A18 or loan it to me?
>
> Thanks!
>
-- 

Jim Muehlberg
Senior Engineer

National Radio Astronomy Observatory
ngVLA Local Oscillator Lead

1180 Boxwood Estates Rd B-111
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www.cv.nrao.edu/~jmuehlbe