[time-nuts] hp 5245L counters with 10544 and 10811 OCXOs

Loney Duncan loney2 at sbcglobal.net
Mon Jan 8 23:08:55 EST 2018


I have two 5245L counters which appear to have had a field mod where the original 1 MHz cylindrical oven standard has been replaced by the 10544 and 10811 10 MHz ones.  Both counters have late 4-digit serial prefixes.  Both of the standards plug into an interface circuit board that, among other things, appears to have a divide by 10 circuit to produce a 1 MHz output to the counter’s oscillator card as the old cylindrical oven standard did.  This card for both has an hp p/n 5245-60033.

My 10811 counter works well, but the 10544 unit has a troublesome intermittent problem that appears to be on the board.  I cannot find a schematic and parts list for this board to troubleshoot and repair it.  These probably were on a change insert into the counter Service Manual, but I’ve yet to find one.  Have checked on Keysight’s website with no success.

Would anyone in this group possibly have these, or point me to an archive that would?  I very much would like to have the 544 unit function.  I have observed that after many decades of aging, a lot of the old original oven standards are out of adjustment range, while my 544 and 811 OCXOs can still be adjusted.  

Thanks very much for your advice.

Loney Duncan  W0GZV

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