Transconductance
Amplifier
Model 8100
 HIGHLY ACCURATE |
7 VOLT
COMPLIANCE |
100 AMPERES to 100 kHz |
 200 mA to 100A in six ranges
100% over range
capability
40ppm short
term stability
0.04% dc and
0.10% ac accuracy
Accuracy
independent of load
Distortion
below -60dB
Complete Front
Panel Calibration
IEEE-488.2
Interface standard
Stable with
inductive loads
High output
impedance
Power Factor
corrected supplies
(PF>0.98 at 100A output)
WIDE CURRENT RANGE / EXTREMELY BROADBAND
The Model 8100 Transconductance Amplifier is a precision, high stability, high
accuracy instrument which produces an output current which is directly proportional to the
input voltage over the frequency range from dc to 100kHz. Six overlapping ranges, with
full scale values of 2mA, 20mA, 0.2A, 2A, 20A and 100A, provide low distortion output
currents from 200uA to 100A. With the exception of the 100A range, for which a 1 V rms
input produces the 100 Arms output current, the transconductance of the other ranges is
set such that a 2Vrms input produces the full scale output current. With the exception of
the 100A range, all of the other ranges may be operated to twice their full scale value
without any deterioration in performance.
LOW TOTAL HARMONIC DISTORTION
The total harmonic distortion introduced by the transconductance amplifier is less
than -60dB up to 10 kHz (typically 20kHz) and less than -40dB to 100kHz for all current
ranges.
AMPLE COMPLIANCE VOLTAGE
The maximum compliance voltage (the maximum permissible voltage which can be
developed across a load connected across the output) is at least 7Vrms (7V for dc) for all
ranges and all frequencies. This high voltage limit permits a large variety of loads to be
driven from the transconductance amplifier. These loads may be resistive or resistive with
capacitive or inductive components without causing any instability in the output current.
An OVERCOMPLIANCE indicator is illuminated when the 7V has been exceeded.
FREQUENCY AND COMPLIANCE VOLTAGE DISPLAYED
Both the compliance voltage (0.00V - 7.00V) and the frequency of the input voltage
drive (10Hz - 500kHz) are continuously displayed by bright seven-segment LED displays.
HIGHER FREQUENCY OUTPUTS AVAILABLE
With the exception of the 20A range and the 100A range which are internally limited
to 110kHz, the Model 8100 Transconductance Amplifier will normally supply full scale
currents up to at least 500kHz into suitable loads.
WIDE RANGE OF APPLICATIONS
The Model 8100 Transconductance Amplifier is ideally suited for calibration of any device
that requires a precision current excitation. High current and high frequency combinations
are available that have heretofore been difficult to obtain. The Model 8100 may be used to
calibrate (or to develop) current transformers, shunts, ammeters and V-A-W meters.
Whenever the compliance voltage limits will allow it, units may be paralleled to obtain
even higher currents.
EASY TO CALIBRATE
The Model 8100 Transconductance Amplifier has a CALIBRATION PANEL on the front
panel which allows the unit to be calibrated without having to remove either the top or
bottom cover. The Calibration Mode is activated by breaking the seal over the CAL key and
then depressing it with a small, narrow screwdriver. When the CAL key is again depressed,
the new calibration points are stored in an internal non-volatile memory.
COAXIAL OUTPUT FOR HIGH CURRENTS
To minimize the output inductance, the current output for both the 20A and the 100A
range is supplied through a coaxial LC connector. The output current for the lower current
ranges, where inductance is not as much of a problem, is supplied through a set of
recessed safety terminals.
IEEE-488.2 BUS CONTROL
The Model 8100 Transconductance Amplifier is equipped with an IEEE-488.2 interface
which incorporates all of the common commands and queries. Any function which can be
entered manually can be sent by a bus controller to the Transconductance Amplifier over
the IEEE interface. In addition, the frequency and the compliance voltage, which are
displayed on the front panel, can be queried by the controller and returned to it over the
bus. The status and states (e.g. current range, standby, etc.) of the Transconductance
Amplifier can also be queried by the controller and returned over the bus. The bus address
is set from the front panel and is displayed both at turn on and when the LOCAL key is
pressed. A REMOTE lamp indicates that the Model 8100 has been placed in its Remote state
by the controller.
SPECIFICATIONS
RANGES AND TRANSCONDUCTANCE
Range (Full Scale) |
Output Current |
Transconductance |
100A |
0 to 100A |
100 Siemens |
20A |
0 to 40A |
10 Siemens |
2A |
0 to 4A |
1 Siemens |
0.2A |
0 to 0.4A |
100 Millisiemens |
20mA |
0 to 40mA |
10 Millisiemens |
2mA |
0 to 4mA |
1 Millisiemens |
TRANSCONDUCTANCE STABILITY (10 MINUTE INTERVAL)
|
0% - 100% of Full Scale |
100% - 200% FS |
Frequency |
±(% of Reading+% of Range) |
±% of Reading |
dc |
±(0.002 + 0.002) |
±0.004 |
10Hz - 10kHz |
±(0.005 + 0.005) |
±0.010 |
10kHz - 100kHz |
±(0.010 + 0.010) |
±0.020 |
| The stability specification is valid after
the Model 8100 has been in a particular configuration for at least 5 minutes. Measurement
system must have a stability which is better by at least a factor of four. |
TRANSCONDUCTANCE UNCERTAINTY (1 YEAR)
|
0% - 100% of Full Scale |
100% - 200% FS |
Frequency |
±(% of Reading+% of Range) |
±% of Reading |
dc |
±(0.02 + 0.02) |
±0.04 |
10Hz - 10kHz |
±(0.05 + 0.05) |
±0.10 |
10kHz - 20kHz |
±(0.10 + 0.10) |
±0.20 |
20kHz - 50kHz |
±(0.15 + 0.15) |
±0.30 |
50kHz - 100kHz |
±(0.30 + 0.30) |
±0.60 |
| The dc uncertainty is based on the average
of the transconductance obtained with a positive and a negative input. The
uncertainties pertain to the transconductance and do not include any variations in the
output current induced by the output capacitance and the reactance of the device under
test. These high frequency effects must be corrected for separately as outlined in
sub-section 1-7 of the instruction manual. |
| OUTPUT OFFSET |
Less than ±0.05% of Range. |
COMPLIANCE VOLTAGE 7Vrms for ac and 7V for dc. The
accuracy of the display is ±0.10V
| TOTAL HARMONIC DISTORTION |
-60dB from 10Hz to 10kHz |
-50dB from 10kHz to 40kHz |
|
-40db from 40kHz to 100kHz |
| |
|
| NOISE |
0.05% of current range in a band from dc to 100kHz |
INDUCTIVE LOADS Free from oscillations for
inductive loads up to 1mH. The quality factor of the inductor (Q) at 200kHz should be less
than 15.
| INPUT IMPEDANCE |
500kW from each input terminal to chassis ground. |
| FREQUENCY DISPLAY UNCERTAINTY |
0.01% of reading. |
DISPLAYS Three LED (10.9mm/.43 inch high)
Displays. One five digit display for Input Frequency, one three digit display
for Compliance Voltage and one two digit display for Calibration Mode. The display is
updated 10 times a second.
IEEE-488.2 INTERFACE SUBSETS SH1, AH1, T6,
L4, SR1, RL1, PP0, DT0, DC1
| TEMPERATURE RANGE |
Operating: 10°C to 35°C |
Within Specifications: 18°C
to 28°C |
|
Storage: -20°C to 60°C |
| |
|
| RELATIVE HUMIDITY |
Less than 80% |
| |
|
| WARMUP TIME |
Thirty minutes for all specifications |
| |
|
| POWER REQUIREMENTS |
207V to 253V, 50Hz to 60Hz, 12A Max. |
Input Power Factor Corrected |
| |
| PHYSICAL |
Weight 36.4 kilograms (80 pounds) |
|
Size 43.2cm x 40.0cm x
55.9cm (17" x 15.75" x 22") |
| ACCESSORIES |
Included: |
L-C connector to screw
terminal adapter |
|
Optional: |
100 Ampere cable pair terminated in high
current lugs. (1/4" mounting hole in lugs to connect to adapter and device
under test) 1, 2 or 3 foot lengths |
APPLICATIONS
The following papers describe in more detail the properties and
applications of the Model 8100 Transconductance Amplifier
Evaluation of 100 Ampere, 100 kHz Transconductance Amplifiers
by Donald T. Hess and Kenneth K. Clarke
Measurements
of Impressive dc Gain Accuracy and Stability |
|
|
