Shure 885tt User manual

PART OF A COMPLETE LINE

The 885TT is part of a full line of mobile microphones, circuitry

products and related accessories.

For a complete listing, contact your Shure Communications

Representative by calling 847.353.3100 or visit

ww.shurecomm.com.

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Voice communication use such as:

•Landmobile •Marine •Transit

APPLICATIONS

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Shure Communications is committed to developing and

implementing intelligent microphone systems and solutions.

As a technology leader in acoustics, signal processing, and RF,

we can help our customers meet their current and future mobile

communication needs.

ABOUT SHURE COMMUNICATIONS

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GENERAL DESCRIPTION

The 885TT is a hand-held, amplified, condenser DTMF communications microphone with an

illuminated keypad.The microphone is ideal for upgrading existing two-way radios for use with

advanced telephone interconnect systems or for new installations. It is designed for rugged and

reliable operation in any mobile communications application.The 885TT has an omnidirectional

pickup pattern and provides extremely clear transmission, even in noisy environments. In addition

to its clear, crisp, natural voice response, the 885T T has extremely low sensitivity to hum pickup

and low susceptibility to radio frequency interference. For installations where transmitter input gain

requires sensitivity modification, the 885TT has convenient, externally accessible screwdriver

controls for independent adjustment of both microphone and DTMF levels.This eliminates the

problem of fixed audio levels and the necessity for disassembling the microphone for adjustments.

Restricting control access also prevents accidental changes common to external controls.

MODEL 885TT

USER GUIDE

DTMF COMMUNICATIONS

MICROPHONE

CONTINUED ON PAGE TWO

TOP-TALK SOUND CHANNELS™FOR

CLEAR VOICE INPUT, EASY HANDLING

BUILT-IN TRANSISTOR AMPLIFIER

(POWERED BY CARBON-MICROPHONE-

TYPE CIRCUIT)

FREQUENCY RESPONSE FROM 200

TO 4,000 Hz,TAILORED FOR VOICE

COMMUNICATIONS

ILLUMINATED KEYPAD WITH POSITIVE

TACTILE FEEL AND AUDIBLE

CONFIRMATION TONES

AUTO PUSH-TO-TALK (APTT)

AUTOMATICALLY KEYS TRANSMITTER

WHEN KEYPAD IS DEPRESSED

CONVENIENT EXTERNAL MICROPHONE

GAIN ADJUSTMENT ACCOMMODATES

MOST INPUT CIRCUITS

SIMPLE, EASY-TO-USE CONTINUOUS-

TONE DIALING

EXTERNALLY ACCESSIBLE DTMF LEVEL

ADJUSTMENT, INDEPENDENT OF

MICROPHONE GAIN SETTING

MODULAR-PLUG COIL-CORD–EASILY

ATTACHED AND REMOVED.AVAILABLE

WITH PLUGS TO FIT MOST POPULAR

RADIO SETS

LOW SENSITIVITY TO HUM PICKUP

LOW SUSCEPTIBILITY TO RADIO

FREQUENCY INTERFERENCE

RUGGED MILLION-CYCLE PLUS™

LEAF-TYPE SWITCH STANDS UP

UNDER SEVERE ENVIRONMENTS

AND CONSTANT USE

HIGH-IMPACT ARMO-DUR®CASE–

STRONGER AND LIGHTER THAN

DIE-CAST METAL, COMFORTABLE TO THE

TOUCH IN HOT OR COLD WEATHER

RUGGED AND DEPENDABLE UNDER ALL

OPERATING CONDITIONS

STURDY, CONVENIENT MOUNTING

BUTTON FOR ATTACHING TO EQUIPMENT

OR NEARBY SURFACE USING

OPTIONAL MOUNTING BRACKET

HANG-UP BUTTON CONNECTION

AVAILABLE FOR MICROPHONE HANG-UP

SENSING (MOUNTING BRACKET MUST

BE GROUNDED.)

FEATURES

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The 885TT is designed for use with most currently available mobile

two-way radio transceivers. For installation convenience, all microphone

and signalling functions, including keypad illumination, are powered directly

from the microphone input circuit of most transmitters, minimizing the

need for equipment modification.The microphone is compatible with a

choice of five-conductor, pre-wired, coil-cord MODULINK® cables (sold

separately), each of which has a telephone-type modular plug on the

microphone end, and a choice of popular transmitter input connectors

on the other. One cable model is supplied without a connector on the

transceiver end so that the user or installer can attach the desired

connector.The cables are instantly changed or replaced without soldering.

The 885TT features attractive, contemporary styling, designed to

blend with most radio designs and vehicle interiors.The microphone is

ergonomically designed; it fits naturally and comfortably in the hand and

is not affected by heat or humidity.The rugged ARMO-DUR® case is

immune to oil, grease, most fumes and solvents, salt spray, sun, rust and

corrosion. It is outstanding in its ability to withstand mechanical shocks

and vibration.The Million-Cycle Plus™leaf-type switch is a double-pole,

single-throw type, de-signed to resist the effects of severe operating

conditions and constant usage. It has nickel-silver blades, and its contacts

are palladium-alloyed for reliable, oxidation-free operation.

The 885TT’s keypad is made of tough silicone rubber, with durable

printed characters that will last the life of the microphone.The

keypad is backlit by red LEDs, easily visible during night operation

and minimizing eye readjustment for night vision.

The 885TT is supplied with a small screwdriver for adjusting the

microphone amplifier gain and DTMF level, and for releasing the

modular-plug microphone cable from the microphone. Mounting

brackets for affixing to radio equipment or other surfaces are available

in quantities of three as Shure RK6MB.

GENERAL DESCRIPTION CONTINUED

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(Test conditions unless otherwise specified:

audio output measured between pin 2 and

ground; PTT switch depressed; no hang-up

button connection; mic and DTMF level

trimmers full clockwise; dc DMM 10 M or

greater input impedance; ac DMM 1 M or

greater input impedance.Test circuit as

shown in Figure 3B.)

Type

Electret condenser (with transistor

preamplifier, DTMF signaling circuitry,

illuminated keypad)

Frequency Response

200 to 5,000 Hz (see Figure 1)

Polar Pattern

Omnidirectional

Output Level (at 1,000 Hz, 1 cm)

-26 dB/Pa (0 dB = 1V/Pascal)

DC Supply Current

2.3 mA

Magnetic Hum Sensitivity

-94 dBV maximum in 1 Oe 60 Hz field

(mic level control full counterclockwise)

DTMF Output Level

1.1 V peak-to-peak

Audio Polarity

Positive sound pressure produces positive

voltage at pins 2 and 6 of modular connector

with respect to ground

Microphone Connector

6-conductor modular telephone type

Environmental Conditions

Operating Temperature: -30° to 60° C

(-22° to 140° F)

Storage Temperature: -40° to 74° C

(-40° to 165° F)

Relative Humidity: 0 to 95%

(non-condensing)

PTT Switch Assembly

Mechanical: Double pole, single-throw,

leaf-type, normally open Electronic: Open

NPN transistor collector to ground; positive

polarity only; maximum on-state current

100 mA to produce 0.8 V or less; maximum

off-state voltage 40V.

Cable (optional choice)

Detachable, 1.8m (6 ft.), 5-conductor

(1 shielded), vinyl-rubber-jacketed coil cord

with modular plug on microphone end

(see Cordset Table for available installed

equipment plugs)

Construction

Case: Black textured high-impact ARMO-DUR®

Switch Button: Black ARMO-DUR®

Keypad: Molded silicone rubber

Dimensions

See Figure 2

SPECIFICATIONS

The 885TT is provided with a rear-case hang-up button for use with a mounting bracket on or near associated equipment. Heavy-duty,

chrome-plated mounting brackets are available in quantities of three as Shure Part No. RK6MB. IMPORTANT:The microphone hang-up button

is connected to the blue cable conductor for radios with microphone hang-up sensing and must be grounded for proper operation.

•SET-UP

CONNECTIONS

The 885TT is designed to operate with two-way radio sets with input circuits similar to those in Figure 3.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 (see Modifications section).

Adjustments

After connection to the communications equipment and with equipment power turned on, the microphone sensitivity and DTMF output levels

should be adjusted with the supplied screwdriver as follows. 1. MICROPHONE SENSITIVITY: Press the push-to-talk button and speak normally

into the microphone while observing transmitter modulation. Adjust the microphone sensitivity control (rear case hole “B” in Figure 5) and

repeat the talk test as required. 2. DTMF OUTPUT: Do not press the push-to-talk button. Depress and hold down a keypad button for a

continuous tone. Adjust the DTMF output control (rear case hole “C” in Figure 5) as required.

Microphone Cables

The 885TT can be used with various MODULINK®microphone cables. Each cable has a modular microphone plug on one end and the

user’s choice of equipment plugs on the other.The MODULINK®Cordset Table supplied with the 885TT 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.

The cable is attached to the 885TT 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 885TT in rear case hole “A” just above the cable jack (see Figure 5) to

unlock the plug and withdraw the plug from the jack.

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PAGE TWO

PAGE THREE

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Net Weight

149 grams (5.2 oz)

Furnished Accessory

Screwdriver . ...................80B498

Optional Accessory

Mounting Bracket (3 in kit) . .....RK6MB

Replacement Parts

Keypad. ..........................RK269

Membrane Switch Assembly......RK270

Leaf Switch Assembly............RK271S

Cable and Modular Plug. ............See

Cordset Table

Warranty

Shure Communications warrants this product

to be free from defects for two (2) years

from the date of purchase. If your Shure

Communications product fails within this

period, call 847-353-3100 in the U.S. for

details on repair, replacements, or refund.

Operation

Operation of all microphone and DTMF

functions requires that the 885TT is connected

to the communications equipment and that

the equipment power is turned on. Power

application can be verified by observing

keypad LED backlighting.

Voice Transmission

1. Hold the microphone comfortably in the

hand, positioned so that the Top-Talk Sound

Channels at the top of the case are near

the mouth.The clearest sound is often

obtained with the microphone at the corner

of the mouth, with the cable away from the

face. 2. Press the push-to-talk button and

make sure the equipment is in the transmit

mode before speaking. 3. Release the

push-to-talk button before dialing.

Dialing

1. Do not depress the push-to-talk button.

2. Press the desired keypad buttons in

sequence. A high-pitched tone will confirm

that the code has been transmitted. 3. When

the first keypad button is pushed, the

transmitter is automatically keyed.The trans-

mitter will remain keyed for approximately

1.5 seconds after the button is released.

Modifications

Certain applications require that the 885TT

be internally modified.These modifications

should be performed by qualified service

personnel only. CAUTION: This micro-

phone contains static-sensitive semiconductor

devices. All work must be performed at a

static-free work station using properly

grounded equipment. Soldering operations

must be performed using a fine-pointed,

low-wattage soldering iron.To perform

internal modifications, disassemble the 885TT

as follows. 1. Turn the equipment power off.

2. Remove the cable from the 885TT as

previously described. 3. Remove the four

screws from the rear of the 885TT case.

4. Holding the 885TT with the rear toward

you and the cable connector downward,

carefully remove the case rear from the

front. Make certain the rear printed-circuit

board does not become disconnected from

the remaining boards attached to the case

front. Carefully pivot the case rear to the

right. Five wires remain attached between

the printed-circuit boards (retained in the

case front), and the switch and lug attached

to the case rear.This exposes the solder side

of the rear printed-circuit board. 5. Perform

the required modification. 6. Carefully

reassemble the case rear to the case front,

guiding the front pin of the push-to-talk

button into the round pivot recess of the

case front. Reposition wires as necessary to

make certain none are pinched between

the case halves. 7. Replace the four screws

and reinstall the 885TT.

E.F. Johnson and Other Unpowered-

Microphone-Input Radios

Certain radios such as those manufactured

by E.F. Johnson do not have biased audio,

that is, there is no power on the audio line

(see Figure 6). For radios with this type of

input, the audio output must be wired to

pin 6 ( not pin 2) of the 885TT’s modular

connector.This is accomplished by using the

red lead (normally the powered audio lead)

for power only and the white lead for audio,

and moving jumper D-E (see procedure

below).This places a bias resistor and noise

filter in the mic circuit. IMPORTANT: To

avoid permanent damage to the 885TT,

this modification must be performed before

using the 885TT with any equipment listed

in the MODULINK®Cordset Table as

requiring it. 1. Open the microphone as

described in the ”Modifications” paragraph

above. 2. Locate red jumper wire (W301)

connected between points “D” and “E” as

shown in Figure 7. 3. Using diagonal cutting

pliers, clip and remove this wire from both

points. 4. Solder a jumper wire (W309)

between locations “F” and “G” as shown in

Figure 7. 5. Reassemble the microphone.

NOTE: This type of radio normally handles

a low-level mic signal; use of the 885T T will

probably require that the audio and DTMF

gain controls be turned down.

Radios with Inverted Logic

Certain radios such as those manufactured

by Ericsson have a positive-going circuit

when the mic is on-hook.The logic of the

885TT can be inverted for compatibility

with these radios as follows: 1. Add the

following components to the rear circuit

board in the positions shown in Figure 8.

PART VALUE TYPE

Q304 86A350 NPN Transistor

C316 10 µF 35 wvdc Electrolytic Capacitor

R317 100K 1/4 W 2% Resistor

R318 1K 1/4 W 2% Resistor

2. Disconnect the blue wire from location

W308 and connect it to W310. See Figure 8.

INFORMATION TO USERS

This equipment has been tested and found

to comply with the limits for a Class B digital

device, pursuant to Part 15 of the FCC

Rules, and as set out in the Radio Interference

Regulations of the Canadian Department of

Communications.These limits are designed

to provide reasonable protection against

harmful interference in a residential

installation.This equipment generates, uses

and can radiate radio frequency energy

and, if not installed and used in accordance

with the instructions, may cause harmful

interference to radio communications.

However, there is no guarantee that

interference will not occur in a particular

installation. If this equipment does cause

harmful interference to radio or television

reception, which can be determined by

turning the equipment off and on, the

user is encouraged to try to correct the

interference by one or more of the

following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the

microphone and receiver.

• Connect the microphone transmitter to an

outlet on a circuit different from that to

which the receiver is connected.

• Consult the dealer or an experienced

radio/TV technician for help.

SPECIFICATIONS CONTINUED

FIGURES

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™ Shure Communications and the ShureComm “web” logo are trademarks of Shure Communications Incorporated. ®Shure, MODULINK, and ARMO-DUR are registered trademarks of

Shure, Incorporated. ™ Million-Cycle Plus and Top-talk Sound Channel are trademarks of Shure Incorporated. All other trademarks are the property of their respective owners.

1676 BARCLAY BOULEVARD BUFFALO GROVE ILLINOIS, 60089 TEL 847.353.3100 FAX 847.353.3131 WWW.SHURECOMM.COM

TYPICAL FREQUENCY RESPONSE

FIGURE ONE

OVERALL DIMENSIONS

FIGURE TWO

MICROPHONE INPUT CIRCUITS

FIGURE THREE

MICROPHONE CASE REAR

FIGURE FIVE

NON-DC-BIASED INPUT CIRCUITS

FIGURE SIX

885TT REAR CIRCUIT BOARD JUMPER LOCATIONS

FIGURE SEVEN

885TT REAR CIRCUIT BOARD LOCATIONS FOR

LOGIC-INVERTING MODIFICATIONS

FIGURE EIGHT

NOTICE:This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference,