The Model 261 Picoampere Source is a secondary standard
for use in calibrating picoammeters and electrometers. The
output of the Model 261 can be adjusted between 10-‘4A and
1.1 x 10.4A in eight decade ranges. The source has 3 digit
resolution for current outputs b#etween 10~12 and 10~4A.
The current output of the Mlodel 261 is derived from a
variable voltage source and a selectable range resistance. The
voltage supply is highly ragulatled for stability and uses highquality
components throughoul for reliability. The low side of
the output can be floated to avoid possible ground loop problems.
1.2 MODEL 261 FEATURES
Important Model 261 features iixlude:
1. 11V Internal Source. The internal voltage source can be set
to a value between 0 and 1’lV in O.OlV increments. This
permits accurate calibration of picoammeters and electrometers
with input voltagt! drops up to 1OmV without
2. Stable High-Meg Resistance Standards. The highmegohm
resistance standards are selected for maximum
stability. Individual temperature coefficients and resistance
values are supplied with each instrument.
3. Line Operation. The Model 261 is line operated from either
105.125V or 210.250V power sources. Voltage selection is
easily accomplished with the rear panel line voltage selection
4. Eight Current Ranges. Eight current ranges are user selectable
with a single front panel control.
5. Shielded Output Connector. The UHF output connector
on the front panel is Teflon@ insulated to minimize possible
6. Floating Low Connection. The low side of the output connection
can be floated to miinimize the effects of ground