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

[Andy Talbot]

My 5061, which I think still has plenty of beam activity, I keep on
standby continuously with just teh VCXO running, and it's been running like
this for about 25 years.   Occasionally, perhaps once per month, turn the
CS on for a few hours, or a day depending on the experiment I need it for.
Although the manual says it needs about two to three hours from turning Cs
on, to switching to run and getting loc up, I find it can often work in as
little as 30 minutes.  Always in less than an hour.

Perhaps my tube is quite healthy.    I know the unit was chucked into the
skip where I found it for "internal political" reasons when the
organisation split up, so it may not have  had much use at all.

Andy
www.g4jnt.com



On Fri, 2 Dec 2022 at 16:17, Jim Muehlberg via time-nuts <
time-nuts at lists.febo.com> wrote:

> It locked.  Wow.
>
> I appreciate all the guidance! Thanks Paul, Rodger, Chris and all who
> commented.
>
> After swapping in a multiplier module (I was missing the A3 Multiplier,
> not the divider module).  I let it warm up and made sure the 5 MHz was
> reasonably close to my best external source.  The mechanism to tweak the
> oscillator is missing from this unit and a real pain to tweak.  So, I
> did not peak the beam current.  After that it would not lock.  I saw the
> 2nd harmonic was almost 0, so I adjusted the loop gain per the manual,
> and voila! it locked!
>
> I've got a HP counter and TimeLab software, so I suppose the next thing
> will be to (learn the software) to make some measurements.
>
> We've got three of these working now. Well, at least they lock. I
> revived a standard unit using the external HV supply, and we have two
> opt 004 units working.  Not sure for how long, though.
>
> What's the best way to keep these beasts running?  Shall I leave them on
> in "CS Off" all the time, or just turn them on when needed?
>
> Again, I appreciate the help!
>
> Jim
>
>
> On 2022-11-30 2:52 PM, Jim Muehlberg via time-nuts wrote:
> > OK, after an 11 day hiatus, there is no change in ion pump current.
> > Still very low (1 uA?) in "CS OFF". Switching to another mode (any)
> > causes the pump current to increase and the A18 output to fold over,
> > then it recovers and keeps doing this at about a 5 second period.  The
> > monitor point reaches about 1.2 V before folding back.
> >
> > So, I found a little laser HV supply that puts out 1250V at 4mA. So, I
> > thought I'd attach that.  On my homemade 172 MOhm Divider, the voltage
> > turned out to be much higher, around 7kV!  Which I only found out
> > after connecting to the tube.  Hopefully, that didn't kill it.  It
> > drew about 50 uA at this voltage.  I ended up leaving for a few
> > minutes before I realized what was going on, since I couldn't believe
> > the reading from my divider.
> >
> > In any event, after reconnecting the A18, ion pump current is very low
> > again, but this time the monitor point stays up at around 4V with the
> > clock in "LOOP OPEN".  It no longer folds back at all.
> >
> > Recall it has no divider module so I'm not sure monitor points are
> > useful, but most are dead, except Supply, Ion Pump I, Osc Oven, CS
> > oven.  There is a tiny bit of Beam current.
> >
> > Next steps?  Did I kill it?  I may have access to a divider module...
> >
> > 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
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