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

[paul swed]

Yup good progress.
Corby discussed this in the thread. Thats the crud burst I mentioned as the
ionizer comes on and releases accumulated dead Cs. The system will keep
toggling on and off. The key is that over time it will stay on longer and
longer as the crud clears. Finally (Fingers crossed) staying on.
You can also cheat given you are the NRAO. With the loop open adjust the
internal 5 MHz osc as close as possible to one of your very good references
after the 5 MHz osc has warmed up for a few hours.
When everything is staying on. Close the loop/Operate and with a drop of
luck you may see some beam current and then second harmonic. At that point
Look at EFC you may be locked. Press the logic reset button. Green light?
Your operating.
Watch out for the lights over time the pin flattens on the lamp and may not
make connection. A drop of solder/heat will reform the base. Or the bulb
can simply be burned out.
Regards
Paul
WB8TSL

On Fri, Nov 18, 2022 at 5:56 PM Jim Muehlberg via time-nuts <
time-nuts at lists.febo.com> wrote:

> Update:  After tearing into the A18 and finding nothing obvious, poking
> prodding and testing, it decided to start working.  I hate it / love it
> when that happens.  I suspect a clearance issue as when I reassembled it
> I could hear it snap.  So I left the cover off.
>
> Voltage at pin 4 is 4.4 unloaded and about 4 connected to the tube.  In
> "CS Off", pump current is 1 on the scale.  Switching to "loop open" or
> "operate" causes the meter to peg and pin 4 goes to 0 or less.  Return
> to CS off, and the power supply recovers in about 20 seconds to about 4
> volts.
>
> I'll leave it on over the weekend and sort through the embers on Monday.
>
> Jim
>
> On 2022-11-09 11:07 AM, Jim Muehlberg via time-nuts wrote:
> > 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
> Charlottesville, VA 22903-4602
> P 434.296.0270
> C 434.422.2017
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