[time-nuts] 5065A Problem

[John Miles]

Suggestions:

1) Was it working before?  If not you may need to follow the cell-flooding
correction procedure in the manual.  Corby Dawson made an informative post
about that phenomenon a couple of years ago, if you can find it in the
archives.

2) If it was working but failed, check the +20V supply at J16 first.  If the
voltage at that jack is OK but no current is being drawn, the Colpitts
oscillator that drives the lamp has failed.  Nothing else will work until
you open the RVFR and fix the oscillator -- which is possible but not much
fun.

Suggest checking the ESR of all of the capacitors on the A11 oven controller
before you put it back into service.  When I got my 5065A I had to replace a
resistor on the oscillator board that had physically cracked from
overheating.  Both C23 and C24 on A11 were open; so were the same two 20
uF/50V capacitors on the battery-charger board.

I don't immediately see how that could have caused the oven controller to
run away, but it was pretty clear that it had happened at some point.
Either way, if the lamp or cell oven current hasn't decreased within 20-30
minutes after turnon, you need to power it down and look for a controller
problem.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of J. L. Trantham
> Sent: Tuesday, February 09, 2010 9:16 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] 5065A Problem
>
>
> I have a 5065A that shows no PHOTO I or 2nd Harmonic.  I am
> suspicious that
> the Rubidium tube is the problem.  There is voltage to the tube and I
> measure no current from the tube directly.  All other indications seem
> normal.  Does anyone have any experience trying to rejuvenate the Rubidium
> tube from a 5065A?
>
> Thanks,
>
> Joe
>
>
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