pete
you can get schematics for any 70000 modules except of the bit
error testing stuff - i got em all on my shelf and bought them
officially from agilent and the level of propriatary parts is not
much higher than the 8566B , consider also that the 8566B is
longer in obsolence than the 70000 so the parts availability is
much worse on the 8566B
Hmm, I wouldn't say that, when you can get a whole parts unit minus the CRT
and cables for $810 (e.g. item 140172731962).
What are the requirements to calibrate a 70000 outfit, by the way? A Tek
2784 is much nicer than a 494, too, and if you turn over the right rocks,
you can even get the schematics for them. But when you open the 2784's
calibration manual, you won't get very far before it tells you to hook up a
lot of very specific (and very expensive) gear including a 40 GHz HP 8350B
sweeper to an MS-DOS PC that's running an obsolete version of Lotus 1-2-3
and some proprietary Tek calibration software.
So, does the 70000 still use actual trimmers, or is calibration mostly
automated and undocumented? After spending a lot of time tinkering with an
8642B signal generator, I am reluctant to recommend that hams and other
hobbyists get into something that tethers them to a professional calibration
lab, or requires them to run one.
Conversely, you can calibrate an 8566 with much cheaper 8620C sweeper gear,
which you probably want on your bench anyway if you're playing in that
league.
I have serviced and sometimes still service both units and i
have seen alot of customers getting rid of their 8566 units
because we couldnt get parts anymore.
Keep in mind that users in home labs don't necessarily care if the parts
come in a shrink-wrapped bag from Agilent.
At the prices we're seeing, most anyone who can afford one 8566 can afford
to keep a parts mule. I don't know if it's that easy to find salvageable
70000 hardware (maybe it is), but one thing I have learned is that you can't
count on long-term parts availability from Agilent.
-- john, KE5FX
