cor/audio board Optional strapping

You can leave out the AF output pot and simply terminate it with a resistor, such as shown here.

For remote system transmitters you don't need the "timeout" timer, however you might want to keep the "tail" timer to filter out any uplink drop outs (intermittent link path). This is also handy for systems that use an "and" squelch control, mult-tone and/or simulcast transmitter control. You would use "PTT-2" for transmitter keying.

For this arrangement, leave out U4 and all its associated components. Strap (the previously U4 pin 3 output) junction of the 10K resistor to a "high" such as Vcc. This will disable U1 from being an "AND" gate, and just work off the carrier signal to drive the tail timer. Beside for an intermittent link path or a system that uses multi tone/transmitter control.

Some prefer the remote transmitter(s) to drop immediately upon link loss of control signal. For this arrangement, disconnect drive resistor lead from the junction of U1 pin 14 and move it to U1, pin 8. Then jumper "PTT 1" to "CON 2". The picture shows both arrangements.

For Remote receivers you don't need the time out nor tail timers. For this arrangement, leave out U4 and U3 and their associated components. Strap the output of U1 pin 14 directly to the resistor driving Q2 and use the "PTT-1" for receiver PTT output.

The board is designed to be universal and easy to modify for your particular needs, limited to your imagination.

This may be copied in complete form only for non-profit purposes, such as for the knowledge for the Amateur Radio Service, with AK2O credited as designer. Other arrangements please contact the author.

Copywrite: AK2O 2007

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