[time-nuts] Re: Attempting to start HP5061A {External}

[paul swed]

Great to hear and with a reading I see in the pix you included thats a nice
tube.
Appears to be 38?? Granted the beam current isn't absolute.
I have a unit with 0 beam current and it still locks and is consistent with
the other CS units.
Regards
Paul
WB8TSL

On Thu, Feb 9, 2023 at 1:42 AM Matt Krick via time-nuts <
time-nuts at lists.febo.com> wrote:

> I am pleased to report that the unit is Alive and Ticking!
>
> After 30 minutes of the cycling my unit stabilized. I have it another 2
> hours of CS OFF mode and then started it again this time stable with no
> cycling.
>
> With Loop Open the Beam meter started at 2 and slowly climbed to about 15
> after about 20 minutes where I did a rough tune.
>
> After another 20 minutes I went with Oper mode and centered the coarse
> tuning getting a peak meter reading of 34. Pegging control to -50
>
> I then centered the control reading by again tuning coarse and hit the
> reset button and got the continuous operation to light.
>
> I set the clock to my watch and will compare tomorrow
>
> On Wed, Feb 8, 2023, 15:22 Aiden Gibson via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
> > Hi Matt,
> >
> > Just to add another 2c to this thread, I went through roughly the same
> > process Jim describes with my 5061A.
> >
> > I also kept the hot wire ionizer powered on in order to catch any neutral
> > particles which may have been affecting the vacuum.
> >
> > I took some measurements of the process to get a rough "pump curve" which
> > can be seen here:
> >
> >
> >
> https://docs.google.com/spreadsheets/d/1zsTUAiDZ92Eb-2lID9Hkoe7ByOylcx_LJ3ktGqG_uac/edit?usp=drivesdk
> >
> > Best of luck!
> > -Aiden
> >
> > Sent from my Verizon, Samsung Galaxy smartphone
> >
> >
> >
> > -------- Original message --------
> > From: Jim Muehlberg via time-nuts <time-nuts at lists.febo.com>
> > Date: 2/8/23 17:34 (GMT-05:00)
> > To: Matt Krick via time-nuts <time-nuts at lists.febo.com>
> > Cc: Jim Muehlberg <jmuehlbe at nrao.edu>
> > Subject: [time-nuts] Re: Attempting to start HP5061A {External}
> >
> > Hi Matt,
> >
> > I just went through this when resurrecting a 5061A option 4 that was
> > about to be scrapped (Horrors!).  My ion pump power supply was flakey,
> > but after I fiddled with it, I got it to work.  I then saw the same
> > behaviour.  Ultimately, I connected an external supply to the ion pump
> > and left it powered for a few days.  This cleaned (or whatever happens)
> > the tube and I was able to lock it.  FWIW, the supply I connected was
> > about 7 kV.  The label said 3KV, but apparently that was under the rated
> > load.  In any event, I thought I wrecked the whole thing.  I was assured
> > by some time nuts that it was OK, and it was.  It's been running
> > continuously now for about 2 months.  Here's an ADEV plot for fun...
> >
> >    Measured against another opt 4.  Both units have an unknown history,
> > and they are 40 year old tubes, so I consider this a success!  Good
> > enough anyway.
> >
> > Good luck, and keep one hand in your pocket.
> >
> > Jim
> >
> > On 2023-02-08 12:39 AM, Matt Krick via time-nuts wrote:
> > > Hello,
> > >
> > > I recently acquired a HP5061A and I am attempting to start it but there
> > are
> > > some things that are puzzling me.
> > >
> > > Per the manual I have left the unit plugged in for 24 hours with mode
> set
> > > to CS OFF set to and I have observed the Ion Pump readings go to 0
> after
> > > about 3 or 4 minutes of first plugging it in.
> > >
> > > So now I am attempting to power up the tube by switching to Loop open
> > and I
> > > can hear another power supply engage. My Ion Pump reading climbs to
> about
> > > 30 after about 10 seconds and then the power supply shuts off. Then I
> get
> > > into a cycle of about 2 seconds on for 10 seconds off with the Ion Pump
> > > going between 20-30 or thereabouts.
> > >
> > > I'm not sure if this is normal and part of the pumping down process.
> > > Should I leave it on or keep trying to run it on CS OFF?
> > >
> > > Am I correct in assuming that with CS OFF the +3500V supply is running
> > and
> > > that is what is acting as the Ion Pump to evacuate the tube, and then
> > when
> > > I switch to Loop open that also powers  up the Cesium Heater and the
> > -2500V
> > > supply?
> > >
> > > I have experience with high power Triodes and Tetrodes where you run
> the
> > > filaments without high voltage to help evacuate the tube so I'm unsure
> > how
> > > a tube like this operates.
> > >
> > > Thank you!
> > > _______________________________________________
> > > time-nuts mailing list --time-nuts at lists.febo.com
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> > --
> >
> > 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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