This listing is for a Main Oscillator Assembly for the USM-393 Signal Generator, which is the hardened version of the HP 8640B.  We understand this will not work in a regular HP 8640B.

This unit was marked as refurbished by the US Air Force and condition code A.

This unit comes from the estate of a Ham Radio operator who collected many various Test Equipment over the years.
We have thousands of items to sell from this recently purchased estate.

Excellent Condition -Marked as refurbished by the US Air Force

We have two of these at the start of this listing.
Price is per part.
If you want more than one, change the Buy It Now quantity to the number you need.
Pictures 1-11 are the first one and pictures 12-22 are of the second - both are in similar condition except the second one's RF connectors are not perfectly round (see pictures 21 & 22)