[time-nuts] Re: Attempting to start HP5061A

[Tom Van Baak]

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!