Resurrecting Old HP 5061B From the Boneyard

[Hawaii596]

Okay, so we have multiple GPS receivers, multiple Rubidiums (Novatech 2950AR - I like them for portable standard use), and three Cesiums ("Caesium" for the eclectic in the crowd).  One is a nicely working 5071A.  The other two are a 5061B(STD) and 5061A(-004).  Trying to resurrect the two elderly Caesiums, there are power supply problems with the 5061A which techs are troubleshooting, and an interesting issue with the 5061B.

The HP 5061B, during initial turn-on (been in storage for a number of years, by the way), One of the first things required is to put in LOOP OPEN MODE with MOD OFF.  Then set Circuit Check to ION PUMP I position and leave it that way until ION PUMP I readings get to no greater than 20 meter reading.  It started at about 44 when I powered it up yesterday.  By the end of the afternoon yesterday, it had gotten down to about 40.  Left overnight this way, this morning it had gotten down to about 30.  Right now it is down to about 28.

So far it has been on I think about 16 to 18 hours or so. 

I am holding out hope that it will get down to the required 20 reading.  What I am wondering is if anyone here knows what that reading actually represents.  Is this some sort of pump down value where the tube is being pumped down to a needed vacuum?  Or what exactly is this reading?

Also, I tried the rest of the turn-on procedure yesterday, and I could not get the 10 MHz Crystal Oscillator to peak at all and unable to get a lock.  Various other readings are unable to adjust to desired values.

I do have good Power Supply reading of about 40.

The other system started to come up (it has the LED clock on the front panel).  It was counting time, then started flickering and went dead.  The Power Supply reading was really flaky and finally dropped to zero.  So we're tracing down bad power supply components.  If anyone has a spare 05061-6150 card for sale, let me know and we'll buy it.

[TAW]

There was an expert on these @ Robins. The guy could do magic on these things. He was the IMs repair guy. Had 30 "queens" in the back (yes 30!) not sure of his name. Will try and find out. Good luck, hope the ion pump isn't bad!

[Hawaii596]

Would love to hear about this.  I am in contact with a gentleman I located on a forum thread who seems to be very knowledgeable about resurrecting 5061A's.  Maybe he's the same guy. 

[microwave-kevin]

REF:5061B

I don't thin the beam will turn on until Ion Pump is below 24, the A (sorry skipped the B model and went to the 5071) manual had a procedure to use an external power supply for units that had been in long storage, should work for the B as well

Aloha

[Hawaii596]

I have experienced the <24 issue.  It has been running in CS OFF mode for a few days now.  I got it down to 16 on ION PUMP I, but after I successfully got a lock and began running, and even got a good stable 10 MHz (as verified with a rubidium locked counter), it lost lock and ION PUMP I has gone back up to about 30 and is now staying there (at 30).

According to some wisdom I've received, I need to just let it sit in that state for days or even possibly weeks to wait for it to pump back down.  I guess we'll see.