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

[paul swed]

Jim
Thats great news to hear. I think I know the part your missing on the 5 MHz
osc. Its like a offset shaft thing. OK now the next simple clue to the
units. What is the beam current reading?
My unit Frankenstein truly is running on fumes it does lock and has never
shown any beam current. The actual circuits are good since I have HP pico
amp generator and meter system and can inject the current at the preamp.
But that said if your meters were say 5-20 that would be great.
Lots of thoughts on how to treat the 5061s. I have 4 and have found the
following works really great for me.
I use an external supply 24 VDC (Wall wart switcher) through a small
dropping resistor to each ION pump running all of the time. All 4 units
draw something less than 1 watt. As compared to running the oven all of the
time. (Not government funded here. chuckle) The benefit of this approach is
that from turning on the unit for real use. They are locked in 20-45
minutes approx. Thats because the system is pumped down.
Even cranky Frankenstein locks.
So thats my 10 cents. But others will have equally fine approaches such as
just using the 5 MHz osc all of the time and occasionally firing up the CS
to adjust it.

Your catching up to Rodger and me on operational CS units.
Regards
Paul
WB8TSL

On Fri, Dec 2, 2022 at 11:17 AM 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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