User's Manual

1-3
2. Line Interface Board P/N 943180-1
Provides remote control transceiver operation on 2 wire dedicated 600 ohm lines utilizing the
EIA multi-tone keying format found in the Land Mobile Industry. A high level 2175 tone
followed by a 1950 Hz guard tone and then a low level 2175 Hz continuous tone is utilized
to key the transceiver. The 943180-1 board can also be jumper strapped for standard
aeronautical 2175 Hz continuous tone operation. DC (15mA) current loop and ground keying
is also supported. However this board does not support 4wire operation.
NOTE P/N 923051-1 is the default board supplied in all units. The EIA multi-tone board
P/N 943180-1 must be special ordered. To determine which remote card your 92-SC
has installed the Configuration label on the side of the rack mount chassis should be
consulted.
1.2.6 Crystal Filter Board Assembly P/N 923069-1
Additional selectivity during receive operation may be obtained using an optional 25 kHz crystal
bandpass filter. An 8.33 kHz bandpass filter is not available. Crystal filters are cut to the
required operating frequency and require 6-8 weeks lead time. This item is interchangeable
in the field. Refer to Paragraph 2.2.5 for replacement instructions. If no crystal filter option
is ordered, jumper board assembly P/N 923074-1 is installed.
1.3 MODES OF OPERATION
1.3.1 Local/Remote Operation
NOTE
Local operation is not disabled when operating in Remote mode and Remote operation is not
disabled when operating in Local mode. The two operating modes operate in parallel.
1. LOCAL OPERATION - In local operation, voice audio, and keying (PTT) functions are
routed from the microphone (not supplied) to the transceiver. Receive audio is routed
to the internal loudspeaker and phone jack located on the front panel.
2. REMOTE OPERATION - In Remote operation, transmit audio, keying (PTT), and receive
audio functions are routed over land lines to the 600 ohm remote inputs. Internal
jumpers can be set for ±DC, ground, or tone transmitter keying, and to provide a DC
squelch signal and RF Output Power signal depending on the remote control board
installed. Receive audio is routed to the internal loudspeaker and is adjustable by the
volume control. Transmit audio is also routed to the internal loudspeaker at an
internally adjustable preset level (see conference audio).