Shure CB42 User Manual

222 HARTREY AVE.. EVANSTON. IL. 60204 U.S.A.

DATA

MODEL

CB42

i

AREA

@

CODE 312/328-9000 . CABLE:

SHUREMICRO

CONTROLLED MAGNETICa CITIZENS BAND MICROPHONE

GENERAL

The Model CB42 LONG RANGER CONTROLLED
MAGNETIC microphone is designed especially for use
with Citizens Band transceivers in either mobile or base
stations. For clearer transmission and improved relia­bility, this small, rugged, dual-impedance microphone
can be used to replace ceramic or dynamic micro­phones supplied as original equipment.

Model CB42 provides crisp, undistorted voice re-

sponse of high intelligibility and high output. Easy

impedance selection at the end of the cable makes the
microphone suitable for connection to either
pedance or low-impedance (ceramic or dynamic) inputs.

The microphone fits naturally and comfortably in the
hand and is not affected by heat or humidity. The ex­clusive

ARMO-DURD case is immune to oil, grease,
fumes, salt spray, sun, rust, and corrosion-and is out­standing in its ability to resist mechanical shocks
and vibration. It is designed to withstand rigorous
operating conditions and constant use.

Microphone Features:

Highly intelligible voice response
Replaces either ceramic or dynamic original equip-

ment microphones
Dual impedance-matches either high- or low-

impedance inputs
Reliable high output CONTROLLED MAGNETIC

cartridge
Unparalleled ruggedness and durability

Tough ARMO-DUR case

Mounting bracket supplied-fits hang-up button on

back of microphone

high-im-

SHEET

CONNECTIONS

The internal connections of Model CB42 are shown

in

Figure

Refer to the Shure CB Wiring Guide enclosed with
the microphone for detailed instructions for connect­ing the CB42 to your transceiver. If your unit is not
listed in the Guide, contact your dealer or Shure
Brothers Incorporated for information. This micro­phone is not designed for use with transceivers requir­ing five-conductor shielded cable. Passage of the CB42
cable through small-diameter connectors may be eased
by lubricating the outer jacket of the cable.

The general wiring procedure for transceiver con­nections is as follows.

Relay or Switching Circuit:

GROUNDED SWITCHING

Most transceivers employ a grounded circuit to
switch from the receive to the transmit position. To
connect the microphone to such a circuit, proceed as
follows.

1.

2. Connect the BLACK lead to the terminal used to

3.

ISOLATED SWITCHING

In some transceivers, an isolated circuit is required
to switch power supply voltages rather than grounds.
If an isolated switching circuit is required, proceed as
follows.

1.

2. Clip and remove the GRAY lead connecting

3.

4. Fasten the two case halves together with the

1.

INTERNAL

CONNECTIONS

FIGURE

1

Connect the RED lead to the terminal used to
complete the transmitter circuit.

complete the receiver circuit. This will usually be
a ground return from the loudspeaker. If a micro­phone switching contact is not required for the

loudspeaker ground, insulate (wrap with tape)

the BLACK cable lead.
Connect the shield to chassis or circuit ground

of the transceiver (see Guide).

With microphone grille side down on a flat sur-

5

face, remove the four No.

screws from the back
of the microphone case; separate the case front
and back. CAUTION: Microphone case is

spring-

loaded; care must be taken to hold the two
halves of the microphone case together to retain
springs in proper position.

switch terminals 2 and

5

(see Figure

1).

Unsolder the BLACK cable lead from switch ter-

minal

3;

solder the BLACK cable lead to switch

terminal 2.

previously removed screws.

Copyright

27A1319

1976,

Shure Brothers Inc.

(PH)

(OVER)

Printed in

U.S.A.

5.

At the end of the cable, connect the RED lead
to the isolated switch contact terminal used to
complete the transmitter circuit.

6. Connect the BLACK lead to the other isolated
switch contact terminal used for power supply
voltage.

7.

Connect the shield to chassis or circuit ground
of the transceiver (see Guide).

CAUTION

Make certain that the shield is not connected to
chassis ground for those models where the Guide
specifies the shield should be connected to circuit
ground.

Microphone Audio Input Circuit:

LOW IMPEDANCE

Connect the WHITE cable lead to the

low-imped­ance microphone audio input terminal. Insulate (wrap
with tape) the GREEN lead.

HIGH IMPEDANCE (ceramic microphone replace-

ment)

Connect the GREEN cable lead to the

high-imped­ance microphone audio input terminal. Insulate (wrap
with tape) the WHITE lead.

NOTE

The high-impedance connection will generally be

used when replacing a ceramic microphone supplied
with original equipment. If you do not know whether
your transceiver requires a high-impedance or a

low-

impedance microphone, follow the wiring instructions
for the low-impedance connection. Check whether
there is sufficient output from your transceiver. If the

modulation output is too low, reconnect the micro-

phone for high impedance.

OPERATION

Model CB42 will operate satisfactorily under all or-

dinary conditions of humidity, heat, and cold. Dropping
the microphone, or other severe mechanical shocks

should be avoided.

Dimensions

See Figure 2

OVERALL

DIMENSIONS

FIGURE

2

Net Weight

340 grams (12 oz)

Packaged Weight

510 grams (18 oz)

MOUNTING

A mounting bracket for permanent installation is

supplied with each microphone (see Figure 3).

y(2:)rr,N)

MOUNTlNG HOLES,

CLEARANCE

FOR

Na

8

SCREWS

SPECIFICATIONS

TY pe

CONTROLLED MAGNETIC@

Frequency Response

200 to 4,000 Hz

lmpedance

Dual. Microphone rating impedance is 150 ohms

(190 ohms actual) and

lection, see section on Connections.

Load lmpedance Range

Low Impedance
High Impedance

Output Level

Open Circuit Voltage*

Power Level

**0 dB

Switch

Push-to-talk switch to actuate microphone circuit
and transceiver relay or switching circuit. Micro­phone circuit normally open in either high or low
impedance.

Cable

1.8m

individually

Case

Light gray ARMO-DUR@

(at 1,000 Hz)

"High". For impedance se-

.........

.......

(at 1,000 Hz)

* *

............

*O

dB = 1 volt per 100 microbars

=

1 milliwatt per 10 microbars

(6

ft) extended, four conductor, two conductors

,200 ohms to 1,000 ohms

.15 kilohms to 100 kilohms

IMPEDANCE

Low

.....

-32.0 dB
mV) (225 mV)

(25

-

51.0 dB

shielaed, coiled cable

High

-13.0

dB

MOUNTING

BRACKET

FIGURE

3

FURNISHED ACCESSORY

Mounting Bracket RK6MB

.........................

REPLACEMENT PARTS

Cartridge R44D
Switch 55A51
Switch Button and Main Plate Assembly
Cable
Case Front
Case Back

..................................

....................................

....

.90C2264

...................................

..............................

...............................

70A4136

65A191H

90R830

FULL ONE YEAR WARRANTY

Shure Brothers Incorporated ("Shure"), 222 Hartrey
Avenue, Evanston, Illinois 60204, warrants to the owner
of this product that it will be free, in normal use, of
any defects in workmanship and materials for a period
of one year from date of purchase. You should retain

proof of date of purchase. Shure is not liable for any
consequential damages. If this Shure product has any
defects as described above, carefully repack the unit
and return it prepaid to the above address. If you are

not in the United States, return the unit to your dealer
or authorized Service Center for repair. The unit will

be repaired or replaced and returned to you promptly,

and if it cannot be repaired or replaced, you may elect
to receive a refund.