2
OPERATION
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. Depress the push-to-talk button and make sure the equipment
is in the transmit mode before speaking.
Dialing
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 transmitted. (The
microphone audio is muted during DTMF tone transmission.)
Operation of microphone and DTMF functions requires that the
AM8T be connected to the communications equipment and that
the equipment power is turned on.
After connection to the communications set, turn the equipment
power On. Pressing the push-to-talk switch and observing the key-
pad LED backlighting can verify power application.
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 necessary, it should be performed only
by Shure Incorporated or by an FAA Approved Service Facility.
Use the supplied screwdriver to adjust the microphone sensitiv-
ity and DTMF output levels as follows:
1.
Microphone sensitivity:
Press the push-to-talk button and
speak normally into the microphone while checking transmitter
modulation.Adjust the microphone sensitivity control (case
back, hole “B” in Figure 4) and repeat the talk test as required.
2.
DTMF output:
Press and hold the push-to-talk button.
Depress and hold down a keypad button for a continuous
tone. Adjust the DTMF output control (case back, hole “C” in
Figure 4) as required.
SPECIFICATIONS
Type
Electret condenser, noise canceling, with transistor pre-amplifi-
er, DTMF signaling circuitry, illuminated keypad
Frequency Response
200 to 4,000 Hz (see Figure 1)
TYPICAL FREQUENCY RESPONSE
FIGURE ONE
Polar Pattern
Bidirectional, noise canceling
Electrical Characteristics
Environmental Conditions
Operating Temperature: -40 to 60° C (-40 to 140° F)
Storage Temperature: -54 to 85° C (-65 to 185° F)
Relative Humidity: 0 to 95% (non-condensing)
Microphone Connector
6-conductor modular telephone type
PTT Switch Assembly
Mechanical: Double-pole, single-throw, leaf-type, normally open
Cable
ALM-88, detachable MODULINK
®
, 1.8 m (6 ft) extended cord
with modular plug on microphone end and PJ-068 aircraft con-
nector on equipment end; and ALM-89 with A4M type connec-
tor.
Construction
Case: Black textured high-impact ARMO-DUR
®
Switch Button: Black ARMO-DUR
®
Keypad: Molded silicone rubber
Dimensions
See Figure 2
Net Weight
(including cable and connector)
283 g (10 oz)
Replacement Parts
Modular plug-cable with PJ-068 plug assembly..ALM-88
A4M type connector ............................................ALM-89
Furnished Accessories
Screwdriver ......................................................... 80B498
Optional Accessories
Mounting Bracket (3 in kit) .................................. RK6MB
FAA Certification
The Model AM8T is FAA Certified for aircraft use under FAA
TSO-C58a requirements. To maintain this FAA Certification, any
service required for the Model AM8T must be performed by Shure
Incorporated or by an FAA Approved Service Facility.
500
1,000
2,000
5,000 10,000 20,000
50
100
200
20
0
+10
±10
Hz
dB
(100
µ
bar acoustic
test signal at
1 kHz, 10 mm)
–11.5 dBV
(266 mV)
–11.0 dBV
(281 mV)
–10.0 dBV
(316 mV)
Audio trim-
pot in factory
preset posi-
tion
–12.8 dBV
(230 mV)
–12.0 dBV
(250 mV)
–11.2 dBV
(275 mV)
DTMF trim-
pot in factory
preset posi-
tion
Operating Voltage
8 V
12 V
28 V
Notes
Audio Output Level*
DTMF Output Level
Dc Supply Current**
6 mA
12 mA
36 mA
*Standard electrical test circuit per RTCA DO-170
**Microphone is powered only while PTT switch is depressed (standby
current = 0 if PTT switch is released)
