[volt-nuts] Keithley Electrometer probe
eb at telight.com
Wed Feb 29 17:52:30 UTC 2012
There is no point to attaching a scope probe to an electrometer,
which is intended for special purpose measurements, having extremely
high input impedance and extremely low bias current. The UHF
connector is insulated with PTFE for very low leakage. If you want to
use it to its capability, anything hooked to it must be low leakage
as well - the connectors and cable need PTFE insulation. The manual
has the specifications and application info you need to figure it all out.
Also note that the 610A, B, and C evolved from all-vacuum tube to
only the front-end being vacuum tube. I believe the 610D (or maybe
the C) was the fully solid-state model, using a MOSFET front-end.
Again, the manuals for the various versions will show which is which.
I found this out the hard way, paying quite a bit for what appeared
to be the latest, solid-state model in an auction, and finding out
later that it was actually one of the older all-tube models - only
the meter was newer - it was used to replace the damaged one in the
old model. Since the model designation is on the meter only, you
can't tell what it really is from the front, so look at the back
nameplate, or better yet, inside, to be sure.
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