[Boatanchors] HP 8640A new owner

[Arthur Shulman]

Thanks to all who took the trouble to reply, especially to those who offered
to send page scans. I have been able to download and examine the complete
.pdf file for the 8640B gen and it has been very helpful. I have been
unable, however, to find any manuals specifically for the 8640A. It seems to
be fairly scarce.

So before I spend a fair amount of cash (nearly what the gen cost) on a
commercial copy of the manual, I would like to get some advice from someone
who is familiar with with the 8640A, which is the model I have.

My instrument seems to operate properly, but I still have a question
regarding reading the markings on the attenuator dial. There is a wide band
connected to a thin line screened on the panel. When the output meter is set
to 0db, where on the marking should one read the attenuator setting?

If the right-hand end of the thin line is the correct setting, the output is
as much as 6 db high, as read by comparing the output to the 30mhz
calibration signal on my HP141T. On the other hand, if I were to insert a 6
db pad, as I would expect to do when doing a receiver alignment at UHF, then
the setting could be inferred to be correct.

Also, Feeding the gen directly to my HF-1000 (really crude try) also
suggests that output might(???) be higher than dial indicates. This level is
consistent across all bands, though, and I don't think there is a general
calibration shift.

Another thought might be to look at the peak DC voltage measured across a 50
ohm load and a diode rectifier. Again, pretty crude.

I'm confused! Any help from the group? Is it time to think about using a
power meter? (I don't have/can't borrow one.) My thought right now is that
perhaps the calibration signal on the 141T might be the best available
reference.

Arthur Shulman