[time-nuts] Flutter Issues with the timebase in Philips PM6654C

[Walter Shawlee 2]

I recently got 3 of these excellent counters, all ex-NASA in excellent 
physical condition.
They all have the PM9696 OCXO option installed, but they also all have 
the same odd problem:

Measuring my very stable GPSDO (which is monitored with another PM6654C),
the new ones constantly bounce around, with a pronounced rapid 0.1-0.3Hz 
flutter.
The reference counter is rock solid, as is the scope monitor, down to 
0.01Hz with no flutter.
No adjustment or setting on the new counters will eliminate it.

I am very puzzled by this effect, as I have never seen this kind of 
short term fault
manifest in multiple units before. Is there anyone with experience with 
these high end
counters that has seen this and knows the correction?

my only tack at this point is to rip one apart, and go through 
everything from power
supplies to the OCXO looking for clues.

any advice appreciated. I must say I do love these counters,their 
performance is quite amazing
when working properly. I also wish I had a source for the 1.5GHz C 
channel input options, as these
had it missing.

all the best,
walter--

Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca
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