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5 SETUP PRO CE DURES
The semiconductors can be damaged by static discharge. Proper handling procedures must be followed.
Do not touch any of the devices inside the modem, and work only in a static free, clean, and dry
environment.
(1) Re move The Top Cover
Remove the two center screws on the top cover of the modem to release it from the base. Pull
straight up on the cover to expose connections and internal DIP switches.
(2) CON NEC TIONS
Line In ter face
Connect the audio wires in accordance with the configurations below:
4 wire ca ble: Con nect the two trans mit wires into pins 4 and 5 of P1. The re ceive wires con -
nect into pins 7 and 8 of P1. SW3.3 and SW3.4 must be OFF.
2 wire ca ble: Con nect the two wires into pins 4 and 5 of P1. En sure that SW3.3 and SW3.4 are
ON.
Ra dio
If the radio is equipped with a 600 ohm balanced interface, connect the transmit and receive
audio lines as shown above for a cable interface.
For a single-ended radio interface, connect P1-3 to the transmit line of the radio and P1-6 to the
receive line. Connecting the receive input to an unsquelched source in the radio will result in
extraneous characters at the data port, unless the squelch detector is set properly.
PTT: The B1474 pro vides an open col lec tor driver for the ra dio PTT at P1-10.
Squelch: The ra dio’s re ceive car rier op er ated switch (COS) can be mon i tored to de tect
when the ra dio is re ceiv ing a sig nal by con nect ing the COS line to P1-7. This sig -
nal is used to in hibit trans mis sions over a busy chan nel.
The in put is ca pa ble of mon i tor ing a level from 0 to 10 VDC.
See “Squelch Po lar ity” un der DIP switch set tings to set the COS po lar ity and
level, or to dis able this fea ture.
If us ing the Op tion 002 trunking soft ware, con nect the ra dio’s RFCTS into the
squelch in put.
Dig i tal Con nec tion
A DB-25S socket on the side of the unit is used to interface with the computer equipment.
The RS232 interface provides a DCE interface using the following signals:
B1474
BARNETT EN GI NEERING LTD.
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