Shure manual Dtmf Aircraft Microphone, Model 888TT User Guide

Shure Brothers Incorporated

222 Hartrey Avenue

Evanston IL 60202-3696 U.S.A.

Model 888TT User Guide

DTMF AIRCRAFT MICROPHONE

The Shure Model 888TT is handheld, amplified, noise± cancelling DTMF communications microphone that is FAA Certified for aircraft application (TSO-C58a). In addition to its extremely clear transmission, even in noisy environ- ments, the 888TT has very low sensitivity to hum pickup and low susceptibility to radio frequency interference.

In instances where transmitter input gain requires micro- phone sensitivity modification, the 888TT has limited ac- cess external screwdriver controls for independent adjust- ment of both mic audio and DTMF levels. This eliminates the problem of fixed audio levels that require disassem- bling the microphone for adjustments. Restricted control access, however, prevents accidental changes common to other types of external controls.

The microphone has an illuminated keypad 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, minimizing eye readjustment for night vision.

The 888TT is designed for use with most currently avail- able aircraft radios. For installation convenience, all micro- phone and signaling functions, including keypad illumina- tion, are powered directly from the microphone input circuit of most transmitters, reducing the need for equipment modification. A three-conductor MODULINK cable (sold separately) has a telephone-type modular plug, with an ef- fective strain relief, to connect to the microphone and a PJ-068 plug on the equipment end for connection to most aircraft radios. This cable can be instantly changed or re- placed without soldering.

The 888TT is ergonomically designed; it fits naturally and comfortably in the hand and is not affected by heat or

humidity. The voice-entry port is at the top of the micro- phone body for simple, natural transmitting. The rugged ARMO-DURcase is immune to oil, grease, most fumes and solvents, salt spray, sun, rust and corrosion. The 888TT is outstanding in its ability to withstand mechanical shocks and vibration. Its Million-Cycle PlusTM leaf-type switch is a double-pole, single-throw type, designed to re- sist the effects of severe operating conditions and constant use. It has nickel-silver blades with palladium-alloy con- tacts for reliable oxidation-free operation.

The microphone is supplied with output levels factory preset to meet TSO-C58a requirements. Adjustments should be made only by an FAA Approved Service Facility or the Shure Service Department.

The 888TT is supplied with a small screwdriver for re- leasing the modular-plug microphone cable from the case and for adjusting the microphone amplifier gain and DTMF level. A mounting loop is supplied affixed to the micro- phone, and mounting brackets for attaching to radio equip- ment or other surfaces are available in quantities of three as Shure RK6MB.

Features:

•FAA Certified for aircraft use

•Detachable MODULINK modular-plug coil cord with PJ-068 aircraft-radio plug

•Noise-canceling with frequency response tailored for optimum intelligibility

•Top-Talk Sound ChannelTM for clear voice input, easy handling

•Built-in transistor amplifier powered by carbon-micro- phone-type circuit

•Illuminated keypad with positive tactile confirmation and audible verification tones

•Convenient screwdriver-accessible microphone gain adjustment accommodates most input circuits

•Simple easy-to-use continuous-tone dialing

•Screwdriver accessible DTMF level adjustment, inde- pendent of microphone gain setting

•Low sensitivity to hum and rf interference

•Rugged Million-Cycle PlusTM leaf-type switch stands up under severe environments and constant use

•High impact ARMO-DURcase, strong, lightweight, comfortable to the touch in hot or cold environments

•Rugged and dependable under all operating condi- tions

E1998, Shure Brothers Incorporated	Printed in U.S.A.
27A3041 (RL)