DESCRIPTION
The Ectron Model 778 Wideband Amplifier / Conditioner is an
ac-line-powered, all solid-state, high-performance, direct-coupled,
wideband differential dc amplifier with transducer conditioning
and filtering capabilities. Among its features are excellent
linearity, stability, low noise, extremely fast overload recovery,
and unique high-frequency common-mode rejection.
Specifically designed to process wideband low-level signals, the Model
778 is ideally suited for use wherever wide bandwidth,
high-frequency common-mode rejection, and outstanding overload
recovery are required.
Up to ten Model 778 Amplifiers mount
in the Model R718 19-inch rack-mount enclosure. Each amplifier
has quick-disconnect rear-panel connectors for all inputs, outputs, and power.
BANDWIDTH, FILTER, and COMMON-MODE VOLTAGE
The amplifier bandwidth is dc to 3 MHz with ±300 V
common-mode-voltage capability and 80 db of common-mode rejection
at 5 MHz. Front-panel-selectable, four-pole-bessel, low-pass
filters provide reduced bandwidths of 10 Hz, 100 Hz, 1 kHz,
10 kHz, 100 kHz, and 300 kHz, plus a wideband position.
As the amplifier frequency response is within 3 dB from dc
to 3 MHz; at frequencies below 1 MHz, an extremely flat response
is provided. For example, from dc to 100 kHz, typical amplitude
response is within 0.5% and is within 1% to 1 MHz. This
means that for the first time it is possible to make precise
data measurements at frequencies from dc to several hundred
kilohertz.
GAIN and ZERO
Amplifier gain is continuously variable from
0.3 to 1000 by ten fixed gain steps from 1 to 1000 in a 1-2-5
step sequence plus a gain vernier of 1 to 0.3. Separate
front-panel recessed screwdriver adjustments are provided for input and
output zero.
OUTPUT
Dual independent outputs are standard. One is a low-impedance
output for general use, while the second output
has a fixed 50 Ω output impedance to match long cables
for high-frequency response. Both outputs are controlled by the filter
switch. Output connectors are BNC.
CALIBRATION
Self-calibration is provided by an internally
generated calibration voltage that is coordinated with
the gain switch. Controls include a front-panel voltage-substitution
CAL / OPER switch and a recessed multiturn screwdriver
level control.
CONDITIONING
Transducer conditioning provides constant-voltage
excitation, front-panel variable from 0 V
to 15 V and a recessed multiturn screwdriver bridge-balance control.
Terminals are also provided on a separate plug-in assembly to accommodate
completion resistors for one-, two-, and four-arm remote bridges,
resistive temperature detectors (RTD's), or any other bridge-type
transducer.
Totally isolated from the amplifier, power,
and case; the excitation supply has exceptional overload
protection and recovery as does the amplifier.
SAFETY
For personnel safety, the frame of each amplifier/conditioner and the enclosure
are connected to power ground and are isolated from all signal
inputs and outputs.
ENCLOSURES
The Model R718 enclosure provides mounting for up to ten Model 778 Amplifier /
Conditioners in seven inches of vertical panel space in a standard 19-inch
rack. Each amplifier is mechanically secured. Power distribution to all amplifiers
is provided from a single ac line cord.
Model R718 Enclosure
Model R718 Enclosure (rear view)
|
