1-8 General Information 8525B/8528 Technical Service Manual
Issue 6 Publication No: 15-02036
Option R (15-way, D-type Plug)
Pin Number Function Signal Level
1 Loudspeaker Ref Spec
2 Remote PTT 0 Volts = PTT
3 Receiver Audio
Output
Special *
4 Power On Momentary 0V for
Power ON
5 Data 5 Volt Logic
6 Data Line Enable 5 Volt Logic
7 Clock 5 Volt Logic
8 Transmit Lamp Modulated by Tx
output
9 & 10 0V Ground
11 Transmit Audio I/P Nom. 1.5Vpp (8kΩ
input impedance)
12 Receiver
Demodulator O/P
Nom. 1.5Vpp (1kΩ
output impedance)
(Min. load 5kΩ)
13 Receiver Audio I/P Special*
14 Interrupt 5 Volt Logic
15 A rail + Battery supply out
* Special: adjusted to suit attached equipment