Specifications

Accessories Connectors
The functions of the 25-pin accessories connectors, ACC-J1 to ACC-J4, are listed in Table 1. The
connectors include PTT and CW control lines, audio and baseband lines for external equipment,
auxiliary power output, serial RS-232 asynchronous data interfaces, and additional dedicated
handshaking and control lines. The functions supported by the serial data interfaces are determined
by the RM500/RM500R software.
Table 1. 25-Pin Accessories Connector, Pin Functions
Pin Designation Description
1 SPKR-
Differential output to the external 8Ω, 8W speaker
2 EXT RX DATA-
Baseband output (0 dBm, 600 Ω)
3 SPKR+
Differential output to the external 8Ω, 8W speaker
4 EXT RX AUDIO+
5 EXT RX AUDIO-
Differential received audio output (0 dBm, 600Ω; not controlled by volume, but
affected by squelch)
6 EXT TX AUDIO+
7 EXT TX AUDIO-
Differential transmit audio input (600Ω input impedance; 0 dBm is required for
full power)
8 PTT IN VOICE Transmission command (short to ground) for voice signals
9 PTT IN DATA Transmission command (short to ground) for data signals
10 PTT IN CW Transmission command (short to ground) for CW (Morse) signals
11 SW A+ Primary DC voltage current limited output (max 1A)
12 DSI/KW C C BDM – Data serial in/external RF amplifier channel change
13 KW ON/OFF External RF amplifier power on/off output
14 EXT RX DATA+ *
Baseband output (0 dBm, 600 Ω)
15 RXA Receive input (point-to-point protocol to host/HLC)
16 TXA Transmit output (point-to-point protocol to host/HLC)
17 EX RESET External RESET input (for BDM)
18 GND Ground
19 KW PTT PTT output to external RF amplifier
20 EXT ALARM External alarm output (open collector, pulled to ground when external alarm is
activated)
21 VPP Flash programming voltage, input to BDM
22 DSC/KW_ALC BDM – Data serial clock/external RF amplifier ALC
23 SQ GATE Squelch open/closed indication output
24 DSO/FAN ON/OFF BDM – Data serial out/Fan control
25 FREEZE/KW TU BDM – Freeze/external RF amplifier tune
6 6888882V03