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PAGING AND DISPATCHING MICROPHONE
222
HARTREY AVENUE
SnUe@
EVANSTON, ILLINOIS
60202-3698
US.A.
THE
SOUND
Of
THE
R?OFEUIONMSO
\YORLWIM
MICROPHONES
AND
ELECTRONIC
COMPONENTS
GENERAL
CONNECTIONS
The Shure Model 450 is a CONTROLLED MAGNETICm Figure
1
shows the internal wiring of the 450
microphone especially designed for high speed intel-
microphone.
ligibility and exceptional reliability for radio com-
munications, paging, and dispatching systems. The
microphone has a high output level, tailored response,
and an omnidirectional pickup characteristic. The 450
can be converted to
MonitorlTransmit switching with
the Shure
RK199S Split-Bar Conversion Kit.
..
DATA
SHEET
MODEL
450
Microphone Features:
Dual impedance (low or high) with impedance switch
for convenient changeover
Finger-tip control bar (locking or non-locking action)
to actuate microphone circuit and an external relay
or control circuit
Long-life switch to satisfy rigorous requirements of
communications and paging systems
Sturdy, high impact ARMO-DURm base and micro-
phone case
Adjustable microphone height
Dependability
-
under all operating conditions
Conversion kit available for MonitorlTransmit switch-
ing
i
PRESS-TO-TALK SWITCH OPERATION
The finger-tip control bar can be used as a locking or
nonlocking switch. To use as a nonlocking switch,
simply depress the control bar and release after
transmission. To use as a locking switch, depress the
control bar and pull it forward. To unlock the switch,
move the bar back and release.
IMPEDANCE SELECTION
High or low impedance is selected by the switch
located on the underside of the microphone base near
the cable entry. The microphone is shipped with the
switch in the "Hi" position.
The low-impedance connection is recommended
where long cable lengths are required or under condi-
tions of severe hum disturbance. The permissible cable
length is practically unlimited, since neither response
nor level is appreciably affected. Shure A95 Series Line
Matching Transformers are available for use in those
cases where a low-impedance microphone line is
desirable but the associated amplifier has a
high-
impedance input. These transformers provide a proper
impedance match between a
19
to 300 ohm microphone
line and a high impedance input, and are available with
various input and output connectors.
For unbalanced high- or low-impedance operation,
the white cable lead is the "hot" conductor for the
microphone circuit; the GREEN cable lead and the
shield are connected to the amplifier or chassis ground.
Set the impedance switch to the proper position. The
RED and BLACK leads control an external relay or
switching circuit.
For balanced-line low-impedance operation, with the
Impedance Switch in the "LO" position, the WHITE and
GREEN cable leads are the "hot" conductors for the
microphone circuit; the shield is connected to the
amplifier or chassis ground. The RED and BLACK leads
control an external relay or switching circuit.
BLACK
CARTRIDQ CONNECTIONS:
RED
8
WHITE- HIGH IMPEMNCE
BLACK
a
WHITE- LOW IMPEMNCE
INTERNAL CONNECTIONS
FIGURE
1
Copyright 1995, Shure Brothers
Inc
27,4246
(OG)
Printed
in
U.S.A