[time-nuts] Buzzing 5061B

J. L. Trantham jltran at att.net
Sat Sep 3 11:52:37 UTC 2011

When you first plug in these, in 'CS OFF', the +3500 VDC power supply comes
on to pump the tube down while the 10811 10 MHz oscillator warms up.  Once
the Ion Pump I goes below abut 25 to 30 on the meter, then you can put it in
'LOOP OPEN' which turns on the CS Oven, the -2500 VDC supply and pretty much
the rest of the system.  Once the CS OVEN warms up, the BEAM I and 2nd
Harmonic come up, you can put it in 'OPERATE', hit the start button and it
should lock.  The clock will 'run' at initial power up in the 'CS OFF' as
long as there is 10 MHz (and thus 1 PPS) output.  That says that the power
supplies are operating and probably normally.

Therefore, assuming my memory of this is accurate and you just have it in
'CS OFF' position, I would be suspicious of the +3500 VDC supply which sits
behind the clock.

Of course, your power transformer would be suspect as well as L1, the choke
that sits in front of it.

Lifting the top and bottom covers and plugging it in should be helpful in
identifying the culprit.

Do you have the battery back up option?  If so, the batteries are 'drained'
from the unit being powered down and the battery charger could also be an

Good luck.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jeffrey Okamitsu
Sent: Saturday, September 03, 2011 5:31 AM
To: Time Nuts
Subject: [time-nuts] Buzzing 5061B

We lost power for several days after the hurricane last weekend.  As a
precaution I pulled the AC plug for my 5061B from the UPS it's attached to
since I was pretty sure that we would be without power for a while and
didn't want to have the unit plugged in when the power came back in case
there was a surge.
Power was restored on Tuesday but I only got around to powering up the
system  this morning.
When  I plugged it in, it immediately started making a buzzing sound -
alomost like an alarm.  The system appears to be working normally otherwise
- alarm LED on, clock advancing, etc.
I've never heard this buzzing  before during power up.
Not knowing what the issue was, I powered the system down.
Anyone have any clue before I start tearing it down?
BTW - I don't see any mention of this in the manual.
Thanks in advance.
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