[time-nuts] TEMEX Rubidium

Erno Peres ernieperes at aol.com
Mon Jan 9 21:14:02 UTC 2012



Hello,
 
I have a Temex RMO  10MHz rubidium osci but no lock signal comes out.

Checking the RS232 diag code  I have the flwng hex code:
                             7D 04 39 8B 41 4A 48 CB

where the second HEX code indicating the Rb signal level  which is in my case  is almost zero and it should be  1,0 to 3,3 Volt.

Opening up the unit/case I found that the 20MHz xtal osci signal level is low, it stops oscillating when I put very close to my finger-tip....and has to be a power reset in order to get it oscillating again...??????.......touching other pars on the PCB found also that  it locks to a freq  and 
the Lock detect level is OK / TTL /  but the 10MHz freq is almost 180 Hz LOW......
playing around with cooling spray on different spot on the PCB sometimes is stops  10MHz and the lock detect voltage  is OK but only a few sec and then drops out again...... the unit prefer to lock to the lower freq and just sometimes locks for a few sec  to 10MHz exactly ....
I have no manual ie. circuit diagram and looking any good advise if somebody had some hands-on  experience to repair this unit. I assume it has problem with the 90MHz VCO circuit........?????

Please help.
Many thanks and rgds,
Ernie.





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