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SPECIFICATIONS
Type
Electret condenser, noise canceling, with transistor pre-
amplifier, DTMF signaling circuitry, illuminated keypad
Frequency Response
200 to 4,000 Hz (see Figure 1)
500 1,000 2,000 5,000 10,000 20,00050 100 20020
0
+10
–10
TYPICAL FREQUENCY RESPONSE
FIGURE 1
Polar Pattern
Bidirectional, noise canceling
Electrical Characteristics
Operating Voltage
8 V 12 V 28 V Notes
Audio Output Level*
(100 µbar 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
DTMF Output Level
–12.8 dBV
(230 mV)
–12.0 dBV
(250 mV)
–11.2 dBV
(275 mV)
DTMF trim-
pot in factory
preset posi-
tion
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)
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, nor-
mally open
Cable
ALM-88, detachable MODULINK, 0.65 m (2.1 ft) coiled
(1.8 m [6 ft] extended) cord with modular plug on micro-
phone end and PJ-068 aircraft connector on equipment
end
Construction
Case: Black textured high-impact ARMO-DUR
Switch Button: Black ARMO-DUR
Keypad: Molded silicone rubber
Hangup Loop: Matte finish stainless steel
Dimensions
See Figure 2
44.4 mm
40.4 mm
(1-19/32 IN.)
(1-3/4 IN.)
70 mm
64 mm
(2-1/2 IN.)
(2-3/4 IN.)
101 mm
(3-31/32 IN.)
1.9 mm
(5/64 IN.)
42.6 mm
(1–11/16 IN.)
36.9 mm
(15/32 IN.)
25.4 mm
(1 IN.)
OVERALL DIMENSIONS
FIGURE 2
Net Weight (including cable and connector)
283 g (10 oz)
Certification
FAA Certified for aircraft under TSO-C58a requirements
FAA CERTIFICATION
The Model 888TT is FAA Certified for aircraft use under
FAA TSO-C58a requirements. To maintain this FAA Certifi-
cation, any service required for the Model 888TT must be
performed by Shure Brothers Incorporated, or by an FAA
Approved Service Facility.
MOUNTING
The 888TT is equipped with a rear-case hang-up loop
and a hang-up button for use with a mounting bracket on
associated equipment.
Heavy-duty chrome-plated mounting brackets are avail-
able in quantities of three as Shure Part No. RK6MB.
CABLE
To attach the cable to the 888TT, insert the modular tele-
phone-type plug in the microphone jack until it locks. To re-
move the cable from the microphone, insert the small
screwdriver supplied with the 888TT in case hole “A” just
above the cable jack (see Figure 4) to unlock the plug and
withdraw the plug from the jack.