[time-nuts] Re: Attempting to start HP5061A

[Matt Krick]

Looking at the inside I believe the unit is from 1980 and had the tube
replaced at HP in 1983.   The label on the door is pristine and hasn't been
used.

I'm thinking the last time it may have been in service was no later than
1992.




On Wed, Feb 8, 2023, 14:31 paul swed via time-nuts <time-nuts at lists.febo.com>
wrote:

> Toms right though the last paragraph is a little misleading.
> In the open position you hear the 2500 V supply. This causes the crud burst
> and the meter climbs.
> At 30ua approx the 2500V supply turns off. The Ion pump pumps down and then
> the 2500V comes back on.
> The effect.
> Slowly but surely the 2500 V will stay on longer. When it shuts off the ION
> pump brings it back down faster.
> Over some time it simply stays on.
> The fact that the tube pumped down so fast is amazing if its been off a
> long time.
> Regards
> Paul
>
> On Wed, Feb 8, 2023 at 4:57 AM Tom Van Baak via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
> > Hi Matt,
> >
> > You're doing everything right. Read Paul's comment about the "crud
> burst":
> >
> >
> >
> https://febo.com/pipermail/time-nuts_lists.febo.com/2022-November/106842.html
> >
> > The entire thread will be of interest to you. Search for "5061A HV
> > Supply" in the sorted monthly archive:
> >
> >
> >
> https://febo.com/pipermail/time-nuts_lists.febo.com/2022-November/subject.html
> >
> > The short answer is it's totally normal for a 5061A to cycle like that
> > if it's been powered off for months or years. Leave it in open loop and
> > once in a while mentally measure the period. You say it's 10 seconds
> > now; it will slowly get faster and faster and eventually finish. The
> > entire process could take many minutes or even many hours; it all
> > depends on how long the tube has been unused. But as long as the cycle
> > slowly gets faster you're all set.
> >
> > /tvb
> >
> >
> > On 2/7/2023 9:39 PM, 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!
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