[time-nuts] RFTGm-II-XO L108 &L109 Oscillator PLL Failure

[k1jos at att.net]

My earlier post described a problem where the XO failed to see any
satellites after many years of continuous use.  This turned out to be a bad
Oncore UT+ GPS and after replacing it, the XO quickly tracked and locked a
3D fix onto 4 satellites.   I left it open out of the chassis on the bench
thinking I would next do a 15-->10Mhz conversion but I noticed after a hour
or so that a new fault appeared "OSC PLL LOCK FAILURE".  I power down and up
and again looked fine for a while but the same fault reappeared.  I checked
the Datum 10Mhz output before and after and it was within some 10mHz.  No
change before or after the fault in control voltage (~15vdc), Temp (39.5C),
Ant Feed current (16mA), Osc voltage (~23vdc) .     However the VFC
initially was 4.85 and at time of failure it was 0.275vdc.  I assume that
issue could be excessive Datum osc jitter or poor VFC, etc.  Is tracking
down the problem worth the effort? .     I would like to try a repair if
only to hone my skills so any advice would be very much appreciated.
 
Jerry NY2KW   


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