TM 11-5820-890-30-4
2-14. PRIMARY CONTROL SIGNALS.
The primary control signals originate at the front panel. They direct the operation of the RT. The connectors,
switches, controls, and circuitry on the front panel are connected to the parent board through three connectors.
They are the front panel switches connector (J1), the display connector (J2), and the audio/data connector
(J3). See figure FO-7.
The function of the radio is controlled by the FCTN switch, When it is set to , primary power is removed
from the RT. The switch position is checked by the control module. If the switch is set to TST, SQ OFF, RXMT,
REM, LD, or , the corresponding line to the control module is set to logic 1 by the switch. If none of these
lines are at logic 1, the control module sets the RT for SQ ON operation.
Primary power (PRI 13 V dc) for the RT is also routed through the FCTN switch. Primary power must be provided
at either pin F of the system connector (P1) or at the battery connector (J6). The 13 V dc will be applied to the
SWITCHED 13 V dc line when the FCTN switch is at any position other than The SWITCHED 13
V dc provides the input voltage for the power supply (1A3 pins B and C). If the FCTN switch is set to , the
13 V dc will be applied to the STBY 13 V dc line. Both SWITCHED 13 V dc and STBY 13 V dc lines are routed to the
ICOM power supply where they are used to power the PRI BTRY PRES and V HOLD lines.
Two voltages are available to retain the fill information in the control module and the ECCM module. They are V
BATT and V HOLD. V BATT is provided by the holding battery and is routed through the FCTN switch. V HOLD is
provided by the ICOM power supply. It is derived from the primary input voltage. If both are present, V HOLD will
be used instead of V BATT. Both are turned off when the FCTN switch is set to
The control module also checks the MODE, CHAN, and RF switch positions. The control module sets the MODE
SW COM line to logic 1 except during remote operation. The control module checks the FH and FH/M lines. If
neither is at logic 1, the RT is set for SC operation. The CHAN switch is BCD encoded as follows:
CHAN
PRESET 0
PRESET 1
PRESET 2
MAN
0
0
0
1
1
0
0
2
0
1
0
3
1
1
0
4
0
0
1
5
1
0
1
6
0
1
1
CUE
1
1
1
When the RT is transmitting, the T/R line is set to logic 1 by the control module. It checks the MED PWR, HI
PWR/M, and HI PWR/V lines from the RF switch. If none are at logic 1, the RT RF output is set for low power
operation. The SIG display circuit uses the RF DETECT, RF PWR A, RF PWR B, HI PWR XMT, PA PWR LVL, and T/R
lines during transmit to drive the display.
The SIG STR RCV signal is used during receive.
During retransmit operation, all of the RXMT connector I/O is controlled by the switching module. See paragraph
2-17 for a description of retransmit operations.
The keyboard display is controlled by the control module.
The SERIAL DATA, DISPLAY CLK, and DISP EN-N
provide the information needed by the display drivers. A DISPLAY INHIBIT line is used by the remote I/O to turn
the display off during remote operation.
2-17
