[Premium-Rx] HP8640B NOISE MEASUREMENT

[Pat1McA at aol.com]

Greetings all,
 
Sorting out my junk collection today I re-discovered two  old HP units:-
 
08640-60504 Noise Phase Lock Circuit
 
08640-60506 Low Noise Amplifier 20Hz - 10MHz
 
I suspect they are parts of an HP8640 locking phase noise measuring  system?
 
Can anyone shed more light on these items and where further info  may be 
found please? 
 
Thanks - please respond offline
 
Pat G3YFK