[time-nuts] WTS: Efratom PTB-100 Precision Timebase

ed breya eb at telight.com
Mon Jul 9 20:30:13 EDT 2018

It's not necessarily a fault in the Rb physics - sometimes "regular" 
circuit or component problems cause the grief.

I have three units kind of like this - "SPTB-100/LN-001," to be exact, 
with 5 MHz out. As I recall, it's similar to the M-100, so close enough 
to use some of its available schematics and info. I had a problem a few 
years back with one that wouldn't lock, and found that a ceramic 
capacitor in the VCOCXO PLL filter had gone bad - leaky, so it never 
settled down. I could not ID the exact circuit or part because that's 
one of the areas that differs quite a bit from the M-100. Replacing the 
cap brought it back to normal operation.

I haven't searched for the "proper" manuals/schematics in a while. If 
anyone knows of these being available, please let me know.


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