Shure Brothers Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
Model 888TT User Guide
DTMF AIRCRAFT MICROPHONE
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.
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.
Features:
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.
•
•
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
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.
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
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.
•
•
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
The 888TT is ergonomically designed; it fits naturally
and comfortably in the hand and is not affected by heat or
Rugged and dependable under all operating condi-
tions
E1998, Shure Brothers Incorporated
Printed in U.S.A.
27A3041 (RL)
Download from Www.Somanuals.com. All Manuals Search And Download.
Microphoneconnectorwiringisshowninthetablebelow.
Microphone Connector Wiring
Pin Color Function
Pin Color Function
1
N.C.
5
6
Black PTT
Switch
DTMF LEVEL
ADJUST (C)
Ground
2
White Dc Bias (+),
Audio Out
Red
Audio Out
(Ac
MICROPHONE
SENSITIVITY
ADJUST (B)
coupled)
3
4
Yellow PTT Switch
7
8
Drain Ground
N.C.
Blue
NC
CABLE
RELEASE (A)
MICROPHONE CASE BACK
The ALM-88 cable is wired at the microphone connector
as shown in Figure 3 at the bottom of the page.
FIGURE 4
2. DTMF output: Press and hold the push-to-talk button.
Depress and hold down a keypad button for a continu-
ous tone. Adjust the DTMF output control (case back,
hole “C” in Figure 4) as required.
ADJUSTMENTS
Operation of microphone and DTMF functions requires
thatthe888TTbeconnectedtothecommunicationsequip-
ment and that the equipment power is turned on.
OPERATION
Voice Transmission
1. Hold the microphone comfortably in the hand posi-
tioned so that the Top-Talk Sound ChannelsTM 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. Depress the push-to-talk button and make sure the
equipment is in the transmit mode before speaking.
Dialing
After connection to the communications set, turn the
equipment power On. Power application can be verified by
pressing the push-to-talk switch and observing the keypad
LED backlighting.
Factory preset microphone audio and DTMF levels are
correct for aircraft radios with standard input circuits (as
defined in RTCA DO-170), and level adjustment should not
ordinarily be necessary. When such adjustment is neces-
sary, it should be performed only by Shure Brothers Inc. or
by an FAA Approved Service Facility. Use the supplied
screwdriver to adjust the microphone sensitivity and DTMF
output levels as follows:
1. Press and hold the push-to-talk button.
2. Press the desired keypad buttons in sequence. A high-
pitched tone will confirm that the code has been trans-
mitted. (The microphone audio is muted during DTMF
tone transmission.)
REPLACEMENT PARTS
Modular plug-cable with PJ-068 plug assembly . . ALM-88
1. Microphone sensitivity: Press the push-to-talk but-
ton and speak normally into the microphone while
checking transmitter modulation. Adjust the micro-
phone sensitivity control (case back, hole “B” in Figure
4) and repeat the talk test as required.
FURNISHED ACCESSORY
Screwdriver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65A1587
OPTIONAL ACCESSORY
Mounting Bracket (3 in kit) . . . . . . . . . . . . . . . . . . RK6MB
SLEEVE (GROUND)
RED
RED
NC
NC
RING (AUDIO)
TIP (PTT)
WHITE
WHITE
PJ-068 CONNECTOR (TO RADIO)
RJ11 CONNECTOR (TO MICROPHONE)
MODULINK CABLE WIRING
FIGURE 3
3
Download from Www.Somanuals.com. All Manuals Search And Download.
ENVIRONMENTAL QUALIFICATION FORM, TSO-C58a
DO-160C
DO-170
PARA. #
CONDITIONS
DESCRIPTION OF TESTS
PARA. #
3.1.1
3.1.2
Ground Survival Low Tempera-
ture and Operating Low Tem-
perature
Ground Survival High Temper-
ature and Short-Time Operat-
ing High Temperature
4.5.1
Microphone tested to Category D1
Microphone tested to Category D1
Microphone tested to Category D1
4.5.2
Operating High Temperature
Altitude
4.5.3
4.6.1
3.1.3
Microphone tested at altitude equivalent to
15,200 m (50,000 ft) = 11.6 kPa (116 mbar, 87
mm [3.42 in.] Hg)
3.1.4
3.1.5
Decompression
Overpressure
4.6.2
4.6.3
5.3
Microphone tested at altitude equivalent to
15,200 m (50,000 ft)
Microphone tested at pressure = 170 kPa; equiv-
alent altitude = –15,000 ft
2.11 & Temperature Variation – Pre-
Microphone tested to Category B for two cycles.
3.2
3.3
3.5
amplifier
Humidity
Vibration
6.3.1
8.5
Microphone tested to Category A for 2 cycles.
Microphone tested to Categories N, B, & M
(Table 8-1, Not on Vibration Isolators)**
3.6
Magnetic Effect
15.3
Microphone tested to Equipment Class Z; no
magnetic properties
3.7
3.8.1
3.9
Voltage Spike Conducted
Induced Signal Susceptibility*
Radiated rf Susceptibility*[
Emission of rf Energy*
Final Distortion
17.3
19.3
Microphone tested to Category A
Microphone tested to Category Z
Microphone tested to Category A
Microphone tested to Category Z
20.5[
21.4
3.10
3.11
After all required environmental tests micro-
phone meets requirements of DO-170, 2.2
3.12
Push-To-Talk Switch Life
Fire Retardance
After all required environmental tests micro-
phone meets requirements of DO-170, Appendix
B, T-7 and 2.9
In accordance with FAR 25; 25.869(a)(4) and
Appendix F, Part I (a)(3)(b)***
*Tests performed at Radiometrics Midwest Corporation,
Lombard, IL
***Tests performed at Gaynes Test Laboratories,
Chicago, IL
[ Tested to DO-160B
All other tests performed at Shure Brothers Inc.,
Evanston, IL
**Tests performed at Elite Electronic Engineering,
Downers Grove, IL
INFORMATION TO USERS
This equipment has been tested and found to comply with the 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:
limits for a Class B digital device pursuant to Part 15 of the FCC
Rules. These limits are designed to provide reasonable protection
againstharmful interference in a residential installation. This equip-
ment generates, uses, and can radiate radio frequency energy,
and, if not installed and used in accordance with the instructions,
Reorient or relocate the receiving antenna.
Increase the separation between the microphone and receiver.
Connect the microphone transmitter into an outlet on a circuit dif-
may cause harmful interference to radio communications. Howev- ferent from that to which the receiver is connected.
er, there is no guarantee that interference will not occur in a particu-
Consult the dealer or an experienced radio/TV technician for
lar installation. If this equipment does cause harmful interference help.
4
Download from Www.Somanuals.com. All Manuals Search And Download.
|