Manual 08640-90017 covers 08640-60383 ser
2520A-2828A and 08640-60483 ser 2835A and above.
So you are looking for a manual prior to 08640-90017.
It appears that there were at least fore different revisions to
this board.
All of the military manuals that I have cover 08640-60023.
Maybe this will narrow down your search.
73
Glenn
WB4UIV
On 3/23/2024 2:58 PM, Renaud F5ZR via
groups.io wrote:
I am working on a US made HP8640B from around 1987. The SN is
scratched which doesn't help but some ICs are dated 1987.
It is working fine and apart from the usual cracked gear, lightly
and only one, no mechanical issue. All the brushes in place.
The two upper bands, 250-500 and 500-1GHz deliver perfectly. All
mechanisms smooth. But no output under 250 MHz so I inquired about
the divider board A10A2.
I swapped the A10A2 board with the one of my other 8640 (UK made
1978). This cured the problem so I now have to repair the faulty
one.
On the left is the old working one whose service manual
"HP_8640B_Maintenance_Manual 1986" I have. I don't have one for
the more recent clearly different.
Anybody know about that "new" design? Thanks.
Renaud
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
