900CT Datasheet, PDF (4/19 Pages) Frequency Devices, Inc. – Tunable Active Filter Instrument

Models 900CT & 900BT
Single Channel – Certified
Model 900 Series
Front Panel Description
AB
Location of Front Panel Terminals and Controls
C
D
E
M
L
K
J
I
H
G
F
A. POWER Status Lamp: This red LED
indicates whether or not the power to the
analog filter circuitry of a Model 900CT/BT
Series instrument is ON. With the power
switch in the ON position, the LED glows
continuously indicating internal DC power
levels are correct. If LED does not light when
power switch is in ON position, 1) reset
instrument by cycling POWER switch OFF
and ON, 2) Check line fuse.
For 900BT models only: If LED is flashing,
recharge batteries, approximately 30 minutes
of operation remains.
B. CORNER FREQUENCY Selector Switch
(0-400Hz): This five position rotary switch
selects the 100’s digit of the corner
frequency designator.
The switch
selectable values are 0, 100, 200, 300 and
400 in five discrete steps.
C. CORNER FREQUENCY Selector Switch
(0-90): This ten-position rotary switch
selects the 10’s digit of the desired corner
frequency between 0 and 90, in discrete
increments of 10.
D. CORNER FREQUENCY Selector Switch
(0-9): This ten position rotary switch selects
the 1’s digit of the desired corner frequency
between 0 and 9 in discrete increments of 1.
E. MULTIPLIER Selector Switch: This four-
position rotary switch multiplies by a factor of
either 0.1, 1.0, 10 or 100, the aggregate value
set on the 3 CORNER FREQUENCY selector
switches. (B, C & D)
F. GAIN Switch: This three-position toggle
switch selects an overall filter gain of 0, 10, or
20 dB.
G. BYPASS Switch: OUT and IN setting of
this two position toggle switch routes the input
signal to the internal filter or around it,
respectively. E.g. OUT position - no Bypass,
the signal passes through the filter. In either
case, the gain switch remains operational.
H. INPUT Switch: This three position toggle
configures the instrument for either differential
inputs (A-B), a single-ended input (A), or input
nulling ( ) which grounds both the (A) and (B)
input terminals.
I. & J. (A) and (B) Input Terminals: This pair
of shielded, female BNC connectors accept
signal inputs (A) and (B). The instrument
applies a non-inverting gain to input (A) and
an equal but opposite inverting gain to input
(B) while the GAIN switch sets the magnitude
of differential gain to 0, 10, or 20 dB. The
BNC shields have been internally connected
to the instrument ground.
K. GROUND ( ) Terminal: This “Banana”
type test jack provides neat and secure
access to the internal ground. This terminal
is a convenient junction for grounding
external system and measurement
instrumentation and/or apparatus.
L. OUT Terminal: This terminal is a female
BNC connector. The shield on the BNC is
internally connected to the instrument ground.
M. OFFSET Adjust: This adjustment is
intended to zero the offset that results from
the instrument’s own circuitry and does not
provide for wide range offset to remove dc
input signals.
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