[time-nuts] HP5345A "modified front end" (p/o HP5390A)

[Charles P. Steinmetz]

I've encountered an HP5345A (prefix 2040A) that was apparently 
originally part of an HP5390A frequency stability analyzer (prefix 
2036A).  It has a factory label (No. 05345-80023) indicating that it 
has a "modified front end."  I have not seen anything in the 5345A or 
5390A documentation to suggest what might have been changed in the 
front end.  Does anyone here know?

So far, the 5345A appears to work normally, but I have not 
characterized its sensitivity or triggering performance.  The 10811 
oscillator does seem to be a cut above the others I have in terms of 
stability -- I don't know if this was intentional or accidental.

Thank you,

Charles