6K V1.02 03-16-91
149
INSTALLING THE S-COM 5K REPEATER CONTROLLER
IN A SPECTRUM COMMUNICATIONS SCR 77 FM REPEATER
1.
Locate the
PRC77 Power Supply/COR/AF Mixer Board.
Cut one end of resistors R305,
R341, and R342. (Cutting R305 inhibits PRC77 control of PTT; cutting R341 and R342
opens the CW ID audio and the RX-to-TX audio paths, respectively.)
2.
Receiver Audio:
Connect the "RX AUDIO" input of the 5K (pin 13) to terminal 3 (the high
side) of R601, the 50k Monitor volume pot mounted on the front panel of the repeater. This
point furnishes high-level, flat audio that has the CTCSS tone filtered out. If the repeater
does not have the optional CTCSS board, then the same audio can be found at terminal
E1105 on the receiver module, and at pin 2 of accessory connector J601.
3.
Transmitter Audio:
Connect the "TX AUDIO" output of the 5K (pin 11) to pin 1 of the
accessory connector J601. Pot R343 on the PRC77 board controls the level of this audio
before being sent to the transmitter.
4.
Receiver COR:
Connect the "RPTR RX COR" input of the 5K (pin 6) to pin 4 of U302 on
the PRC77 board. The easiest way to accomplish this is to solder to the end of R321
nearest U302. The voltage at this point will go high when a carrier is present; therefore, set
the "RX" dip switch on the 5K board to the OFF position.
5.
Transmitter PTT:
connect the "TX PTT" output of the 5K (pin 10) to terminal E1205 on the
transmitter module. Since the 5K must provide a logic low level to this terminal to key the
transmitter, set the "TX" dip switch on the 5K board to the ON position.
6.
Ground:
connect any of the GROUND pins of the 5K (pins 14 thru 25) to pin 9 of accessory
connector J601.
This completes basic installation requirements. Local microphone operation is retained.
If no control receiver is to be used with the 5K, be sure that the 5K
’s "CT" dipswitch remains
in the ON position.