99RE255
TDFM-136 Installation & Operating Instructions
3-4
Technisonic Industries Ltd.
3.7 Wiring Instructions
Figure 3-3 shows all required connections and recommended wire sizes for the TDFM-136
Transceiver operation in the airframe.
3.7.1 Main Power +28VDC
The main power +28VDC (
?
15%) is connected to pins 7 and 14 of the transceiver. Both
pins should be connected.
3.7.2 Main Ground
Ground connections for the transceiver are made on pins 8 and 15. Both pins should be connected
3.7.3 PTT (Ground Keying)
The PTT line is connected to pin 13 and should be floating when the transceiver is in receive mode,
and grounded during transmit mode.
3.7.4 Front Panel Back Lighting
Front panel back lighting connection should be made on pin 3 of the transceiver. The opposite end
of this lead should be connected to the panel lighting system of the aircraft. Before connecting, verify
the required panel lighting voltage (28 VDC or 5VAC) on the transceiver configuration control label.
3.7.5 Audio Outputs (600 ohms and 4 0hms)
The audio output from pin 9 can be used to drive a 4 ohm speaker up to 2.5 watts. Audio output from
pin 1 is 600 ohms, 0.5 watts maximum.
3.7.6 Audio Output Ground
Pin 10 is the ground for both the 4ohm and 600 ohm audio output signals on pins 9 and 1.
3.7.7 Mic Signal Input
The microphone input signal is to be provided on pin 6, utilising shielded wire with the shield grounded
to pin 10.
