S-COM 6K Owner's Manual page 20

9. RECEIVER #2 (CONTROL/LINK RECEIVER) CTCSS DECODER
If you decide to add a second receiver, you have the option of adding a CTCSS decoder to it. After
installing the decoder into the receiver, connect the decoder's logic output to pin 16 of the
controller's J2 connector.
The controller's RX2 CTCSS Decoder input circuitry is designed exactly like the RX1 COR input.
The transistor in this case is Q1A, the voltage divider is made up of R11A and the resistor on pin 2
of R12, and the pullup resistor is R16. You may wish to refer back to the "RECEIVER #1 COR"
section of this manual for a discussion of the hardware design of the input circuit.
To check your RX2 CTCSS decoder interface, power up the second receiver, its CTCSS decoder,
and the controller. Measure the voltage at pin 16 of J2. This voltage must swing above and below
the 2.1 V threshold as the incoming CTCSS tone is applied and removed.
You must also determine the "sense" of your CTCSS decoder output. Does the output go "low" or
"high" when the correct CTCSS tone is received? If the output goes "low" when the tone is
detected and returns "high" when the tone is removed, then place dip switch #4 (part of S2) in the
ON (closed) position. If, however, the output goes "high" when the tone is detected and returns
"low" when the tone is removed, then place dip switch #4 in the OFF (open) position.
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6K V1.02 03-16-91