Shure 550T, 550TS User Guide

OMNIDIRECTIONAL PREAMPLIFIED DYNAMIC BASE STATION MICROPHONE

MODULINK

Note: After unpacking the microphone, remove

the protective film from the nameplate

GENERAL

The Shure 550T and 550TSB Series II Modulink Base
Station Microphones are rugged, omnidirectional dynam­ic microphones with a built-in preamplifier. Designed for
optimum voice clarity, they can replace dynamic or ceram­ic, high- or low-impedance microphones supplied as origi­nal equipment. Both models provide radio communica­tions, paging and dispatch systems with clear, high output
voice transmission, even in noisy environments.

The 550T and 550TSB Series II are MODULINK
versal replacement microphones. They are compatible
with a variety of five-conductor, shielded, coil-cord cables
(sold separately), each of which has a locking, telephone­type modular plug on the microphone end. One cable type
has bare tinned leads on the transmitter input end so that
the user can install any desired connector. Since cable
damage is the major cause of microphone failure, this in­novation allows economical, quick and simple repairs.

The 550T and 550TSB Series II microphones have ex­tremely low sensitivity to hum pickup and low susceptibility
to rf interference. A built-in preamplifier makes them com­patible with biased-audio (powered audio) radio commu­nications systems. An externally accessible microphone



SYSTEM I



uni-

Model 550T and 550TSB Series II Modulink

Base Station Microphone User Guide

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-amplified) mode.

An especially useful feature for shared-channel radio
systems using the Continuous Tone Coded Squelch Sys­tem (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 opera­tor is forced to verify that the channel is clear before trans­mitting. The Monitor switch can also be locked into the “on”
position, if desired, by sliding it forward.

The 550TSB Series II microphone is functionally and
electronically identical to the 550T Series II, but it has a
single PTT switch instead of a split bar PTT switch. The
550TSB Series II can be used with trunking or other radio
systems which do not require the channel monitoring.

Both microphones are ergonomically designed; the
pushbuttons and grasping surfaces conform naturally to
the hand. The virtually indestructible ARMO-DUR
is immune to oil, grease, most fumes and solvents, salt
spray, sun, rust and corrosion. It is outstanding in its ability
to withstand mechanical shock and vibration.

The microphones’ Million-Cycle-Plusleaf switch is de-
signed for constant use even under extreme conditions.
Its nickel-silver plated blades and palladium alloy con­tacts resist oxidation for years.

Features

• Modular-plug coiled cord—easily changed for other

radio sets or to replace defective cable. A genuine uni­versal replacement microphone

• Built-in preamplifier with convenient external gain ad-

justment

• Dynamic cartridge with omnidirectional pickup pattern

• Frequency response tailored for optimum speech in-

telligibility, and clear, crisp response

• Low sensitivity to rf interference and hum pickup

• Rugged, lockable PTT switch stands up under severe

environments and constant use

• High-impact ARMO-DUR case is stronger and lighter

than die-cast metal



case

2004, Shure Incorporated
27B3024 (Rev. 7)

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Printed in U.S.A.

MODIFICATION

The Monitor switch as provided is normally closed for ra­dios with scanning or CTCSS functions that open when
the switch is depressed. For radios that require a normally
open (closed circuit when the microphone Monitor switch
is depressed) such as many Ericsson/GE models, per­form the following modification.

1. Remove the baseplate by removing the screws secur-

ing it to the microphone.

MICROPHONE CONNECTOR WIRING

Pin

Color Function Pin Color Function

1 NC –– 5 Black PTT

Switch

Ground

2 Red Bias (+), DC

6 White Audio

Audio Out

3 Yellow PTT Switch 7 Drain Ground

4 Blue Monitor 8 NC ––

2. Locate the yellow wire from the printed circuit board to

the monitor switch.

3. Unsolder the yellow wire from the top terminal of the

monitor switch and resolder it to the lower open termi­nal of the monitor switch.

4. Replace the baseplate and screws.

MICROPHONE CABLES

The 550T Series II can be used with various MODU­LINKmicrophone cables. Each cable has a modular mi-
crophone plug on one end and the user’s choice of equip­ment plugs on the other. The MODULINK Cordset Table
supplied with the 550T Series II lists the most popular ra­dios available and the cordset (ALM-) designed for use
with each. Note that the ALM-1 has no connector on the
equipment end; it can be wired as needed.

7 8

CONNECTIONS

The 550T Series II is designed to operate with two-way
radio sets with input circuits similar to those in Figure 2.
When wiring ALM-1 cables with connectors for radios not
listed in the table, modular connector pin 2 is to be used
for the dc bias resistor on the input.

1 K560

PIN 2

15 µF

PIN 7

9.6 VDC

FIGURE 2

ADJUSTING OUTPUT LEVELS

To adjust the output level, proceed as follows:

1. Insert a screwdriver into the sensitivity control poten-

tiometer, located in the microphone base (see Figure 3).

2. Rotate the control counterclockwise to increase sensi-

tivity or clockwise to decrease sensitivity.

MODEL ALM-1 CABLE WIRING

FIGURE 1

The cable is attached to the 550T Series II by inserting the
modular telephone-type plug in the microphone jack until it
locks. To remove the cable from the microphone, insert the
small screwdriver supplied with the 550T Series II in bottom
case hole adjacent to the cable jack (see Figure 3) to unlock
the plug and withdraw the plug from the jack.

SENSITIVITY

ADJUST

(CCW MAX.)

MODULINK

CABLE RELEASE

FIGURE 3

INTERNAL CONNECTIONS

The circuit board layout is shown in Figure 6 and the in­ternal electrical connections are shown in Figure 7. A sche­matic diagram of the circuit board is shown in Figure 8.

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SPECIFICATIONS

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Á

Test Conditions: (unless otherwise specified)

Audio output between pin 2 and Ground
Mic level trimmer full CCW
PTT switch depressed
Measured with High Z DMM
Standard test circuit as shown in Figure 2

Cartridge Type

Dynamic (with preamplifier)

Frequency Response

200 to 5,000 Hz (See Figure 4)

+10

0

–10

RELATIVE RESPONSE IN dB

DC Supply Current

2.5 mA ±0.25 mA

Cable (optional choice)

Detachable, 1.2 m extended (48 in.), 5-conductor (1
shielded), Neoprene-jacketed coil cord with modular
plug on microphone end (see supplied Cordset Table
for available installed equipment plugs)

CERTIFICATION

Eligible to bear CE Marking. Conforms to European EMC Direc­tive 89/336/EEC. Meets applicable tests and performance crite­ria in European Standard EN55103 (1996) parts 1 and 2, for resi­dential (E1) and light industrial (E2) environments.

Net Weight

736 grams (1 lb 10 oz)

Overall Dimensions (Figure 5)

50

100

432

FREQUENCY IN HERTZ

TYPICAL FREQUENCY RESPONSE

FIGURE 4

Polar Pattern

Omnidirectional

Sensitivity (at 1 kHz)

Cartridge Direct Output:
–35.5 dBV (16.8 mV)/100 µbar
Amplified Output:*
–4 dBV (0.63 V)/100 µbar

*Using standard test circuit shown in Figure 1, with microphone sen­sitivity adjustment trim potentiometer set to maximum (counter­clockwise).

Hum Sensitivity

34 dB maximum equivalent SPL per 1 mOe, 60 Hz
electromagnetic field

Output Impedance

190 Ω direct output

Switches

Press-to-Talk: Double-pole, double-throw, leaf-type
switch; push-to-talk function normally open, cartridge
shunt normally closed

Monitor: Single-pole, double-throw, leaf-type switch;
normally closed

9876543298765

20000100001000

FIGURE 5

FURNISHED ACCESSORY

Hardware Kit 90SJ1371. . . . . . . . . . . . . . . . . . . . . . . . . . .

REPLACEMENT PARTS

Cartridge Assembly R147. . . . . . . . . . . . . . . . . . . . . . . . . .

For additional service or parts information, please con­tact Shure’s Service department at 1-800-516-2525. Out­side the United States, please contact your authorized
Shure Service Center.

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J3 J2 J1 J4

J5

C6

C3

R5

R4

R3

C7

C8

Q1

L1

C11

C2

R2

C1

C10

R1

C9

J6

C4

J7

J8

C5

FIGURE 6

CARTRIDGE

NOTES:

1. ALL RESISTORS 1/4 W, 2%, UNLESS OTHERWISE SPECIFIED.

2. ELECTROLYTIC CAPACITORS SHOWN IN µF X VOLTS.
NON-POLARIZED CAPACITORS IN µF, 10%, 50 V OR MORE UNLESS
OTHERWISE SPECIFIED.

3. R5 GAIN ADJUSTMENT FROM BOTTOM SIDE OF BOARD.

Transmit Monitor

1

23

BLACK

WHITE

RED

ORANGE

BLACK

WHITE

GREEN

J1

J4

J3 J2

WHITE

SHIELD

J5

J6

YELLOW

FIGURE 7

BLUE

J7
J8

RED

ORANGE

4

GREEN

5

YELLOW

CCW

DC BIAS/AUDIO OUT

PTT HI

MON

PTT LO

AUDIO OUT (DIRECT)

7

GND

FIGURE 8

SHURE Incorporated Web Address: http://www.shure.com
5800 W. Touhy Avenue, Niles, IL 60714-4608, U.S.A.
Phone: [phone] Fax: [phone]
In Europe, Phone: [phone] Fax: [phone]
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