The whole of precision.
The 1621 represents the first major improvement in nearly a decade
in ultraprecise laboratory capacitance intercomparisons and dielectric
measurements. It is a completely self-contained system capable
of capacitance measurements in increments as small as 0.1 aF (10-7
pF) and conductance measurements in increments as small as 100
aS (10-10 µS; equivalent to a shunt resistance
of 1010 MΩ). Measurements are three terminal,
with 2- or 3-terminal connection, and provision is also made for
the connection of an external standard for comparison measurements.
Such capability and precision are usually accompanied by restricted
frequency and complex operation. The 1621, however, avoids these
difficulties. Little degradation of performance occurs from 10
Hz to 10 kHz and operation to 100 kHz is possible. Balances are
achieved by in-line readout lever switches-easily adjusted and
read correctly. All digits of capacitance and conductance, as
well as pertinent multipliers, are also provided by BCD-coded
contact closures, available* at rear-panel connectors for use
by printers or data-processing equipment.
Three integrated units. The 1621 is an assembly
of three integrated instruments: A precision ratio-arm bridge,
a highly stable oscillator, and an extremely sensitive detector.
Most of the bridge's internal standards are enclosed in an insulated
housing to reduce the effects of ambient temperature changes;
unused standards are disconnected to reduce shunt capacitance
at the detector input. The oscillator provides up to 125 V or
5 A for sufficient signal to be detected even with unbalances
as small as one part in 108 of 10 pF. The detector contains three
meters to help you speed the balance: One displays the magnitude
and the other two simultaneously display the in-phase and quadrature
components of any unbalance.
Comprised of a 1616 manual bridge, 1238 detector and 1316 oscillator,
the 1621 Capacitance Bridge is the most accurate manual capacitance
bridge available. The 1238 and 1316 are decade switch controlled.
The heart of precision. The 1616 is the heart of the 1621 Capacitance-
Measuring Assembly. The bridge is also available separately for
use where oscillator and detector are on hand or in applications
in which they must be specialized for a unique need.
The 1616 employs a transformer ratio-arm bridge with which unbalances
as small as 0.1 aF (10-7pF) and 100 aS(10-10 µS) can be
resolved Detection of such small unbalances is aided by ratio-transformer
voltage< capabilities up to 160 volts at 1 kHz and by range switching
that disconnects the unused internal standards in order to reduce
shunt capacitance across the detector input.
For thermal stability in precision intercomparisons, eight of
the twelve internal capacitance standards are mounted in an insulated
compartment to reduce the effects of ambient temperature changes.
Misreading the values at balance is virtually impossible due to
direct-reading lever switches that control the balance for both
capacitance and conductance. Panel layout is unusually neat-only
the unknown capacitor and , if desired, and external standard
for comparison measurements are connected to the front panel;
the oscillator and detector are connected to the rear as are the
BCD data-output channels. |
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