[time-nuts] hp5061a/b no I beam current

[service at frequencystandards.com]

>    3. hp5061a/b no I beam current (paul swed)
> Message: 3
> Date: Sun, 18 Oct 2009 12:25:30 -0400
> From: paul swed <paulswedb at gmail.com>
> Subject: [time-nuts] hp5061a/b no I beam current
> To: time-nuts at febo.com
> Message-ID:
> 	<ac803ca80910180925y78cf028ai31e6560554264d62 at mail.gmail.com>
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>
> Lets see if this works.
> I am new to the time-nuts user group
> Just obtained a HP 5061a CS standard. Pumps down very well to 0 (Hard to
> believe) But it did.
> CS oven comes up to temp. But in operation no I beam current.
> Noticed that the tube states -2083V multiplier. But its regulating to
> -1606V
> can adjust to 2083.
> Still no current. Also no 2nd harmonic but with No I that's what I expect.
> Its an interesting unit from the naval observatory.
> I have the traditional 5061 a service manual. Its halfway between a A and
> a
> B unit.
> As example A15 power reg is using ICs and I found a website with that
> schematic.
> The CS control board A11 also is using ICs at least 3 switching supplies
> us
> SG3524s
> I would like to see a schematic of this if anyone has it. Though I suspect
> that the CS board is fine.
> I want to check several of the voltages though.
> Any help would be appreciated.
> Thanks

Paul, there are several different versions of the A15 board. To get the
correct schematic, you will need the part number which is etched on the
board. It will be something like 05061-6199. The series number will also
help. It may be on a sticker lable or etched, depending on the age of the
board.
The A11 module also has more than 1 version. 05061-06144 is the last one
if my memory serves right. Hopefully you don't have one with several round
epoxied transformers on it with lots of taps. If you do, that means you
have the old AC controller. You can probably tell that just by listening
for the whistle of it. The DC ones don't whistle. Since you said the Cs
oven comes up to a normal meter reading, you are probably safe in saying
that A11 is OK.
The first key though is to make sure that the 5Mhz oscillator is on
frequency. If it is very far off, you will not get 2nd harmonic or beam
current. If you are off even 1/2 hz, it is too much. I usually try to get
them within 3 millihertz before look8ing for beam current. Be careful
turning the coarse frequency adjust, it only takes a small fraction of a
rotation to make a very large frequency change. You can twist them off if
you try to turn too hard and are at the end of the adjustment range.
There are several sites hosted by Time nuts members that have manuals for
the 5061 scanned in. I dont believe any of them charge you to download a
copy. Don't remember off the top of my head which sites they are. Try to
find one as close to the series of your unit as possible. If not exact, go
for the next series up as they contain backdating info in all of them. If
you aren't familiar with finding the series, it is the first 4 digits of
the serial numbers on the back of the unit. This does not mean all the
modules in the unit are this series, it is just the series of that unit.
Let us know how you make out.
Chuck Norton