The Keithley Model 410 Micro-microammeter is a line operated
vacuum tube electrometer designed and constructed especially for
measuring small currents.
Full scale ranges are from 10⁻³ to 3 x 10⁻¹³ ampere,
The features include full-scale voltage drop at the lnptit of
less than five millivolts, zero drift of less than 2% of full scale
in eight hours, good accuracy and calibration stability, and simplicity
of operation. It also has an output which will drive a O-l
or 0-5 milliampere recorder as well as the numerous potentiometer -
rebalance recorders; one output terminal is at ground, making it
convenient to connect cathode ray oscilloscopes or pen-driving
amplifiers, similar to the Brush and Sanborn equipment.
The major panel controls are the range switch (amperes fullscale)
and the zero. Minor controls are the Zero Check, used to
short circuit the input and in setting the zero, Meter Polarity
Tar providing up-scale readings for currents flowing in either direction,
and an ON-OFF power switch. The mater dial is illuminated,
and these bulbs serve as the pilot light.
The Keithley Model 41OC is identical to the Model 410, except that
the panel meter is provided with contacts which can be set to
close at any predetermined meter pointer deflection. The delicate
contacts of the meter operate a relay in the 410~7, and the relay
contacts (SPDL') are available for external switching functions
through an AN connector on the rear of the chassis.