Shure us pro 450t microphone

Page 1

SHUREQ

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MICROPHONES AND ELECTRONIC COMPONENTS

222 HAFITFIEY AVENUE
EVANSTDN, ILLINOIS 80202-3898 U.S.A.

DATA SHEET

MODEL 450T

450T PREAMPLIFIED BASE STATION MICROPHONE

GENERAL

The Shure 450T Base Station Microphone is a rugged,
omnidirectional dynamic microphone with a built-in pre-
amplifier. It provides radio communications and dispatch
systems with clear, high output voice transmission, even
in noisy environments.

The 450T has extremely low sensitivity to hum pickup
and low susceptibility to RF interference. A built-in pream-
plifier makes the 450T compatible with biased-audio
(powered audio) radio communications systems. An ex-
ternally accessible microphone sensitivity control, located
under the base, allows the operator to adjust the output
level. If desired, the preamplifier can be bypassed and the
microphone can be operated in the direct output (non-am-
plified) mode.

An especially useful feature for shared-channel radio
systems using the Continuous Tone Coded Squelch Sys-
tem (CTCSS) is the split-bar Press-to-Talk (PTT) switch.
The Transmit side of the switch can only be actuated when
the Monitor side of the switch is depressed, so the opera-
tor is forced to verify that the channel is clear before trans-
mitting. The Monitor switch can also be locked into the on
position, if desired, by sliding it forward.

Copyright 1992, Shure 5mm Inc.
27A2682 (L!)

The microphones height can be adjusted for greater op-
erator comfort, and its rugged ARMO-DUR® case is virtu-
ally indestructible.

Features

. Built-in preamplifier

. Dynamic cartridge with omnidirectional pickup pattern

. Frequency response from 200 to 4,500 Hz, tailored for
optimum speech intelligibility

. Low sensitivity to RF interference and hum pickup

o Lockable split-bar PTT switch

. Adjustable microphone height

. Rugged ARMO-DUR case

ADJUSTING OUTPUT LEVELS
To adjust the output level, proceed as follows:

1. Insert a screwdriver into the sensitivity control poten-
tiometer, located under the microphone base.

2. Rotate the control to the right (clockwise) to increase
sensitivity or to the left (counterclockwise) to de-
crease sensitivity.

SETUP
The 450T may be used in one of three electrical configu-
rations:
Option 1 : (As Shipped) Two wire operation (biased audio
line - do and audio combined)

Option 2: Three wire operation (unbiased audio, separate
dc line to microphone)

Option 3: Cartridge direct output (passive operation - no
power required)

Options 2 and 3 are implemented by cutting or moving
the jumpers as shown in the tables on the following page.
To configure the jumpers, refer to the printed circuit board
legend in Figure 5, as well as the schematic diagram in
Figure 6, and proceed as follows:

1. Remove the base plate by removing the screws se-
curing it to the microphone.

2. Configure the jumpers according to the tables on the
following page. Refer to Figure 5 forjumper locations.

3. Reinstall the base plate and the screws.

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