I saw a web page detailing how to connect a DTMF box to the rear of
the radio via a radio shack DTMF generator. That generator does not
seem to be available now. Has anyone built a box from something
else. I was even thinking about an old phone..
Keith-
The touchtone pad in an old telephone has numerous wires connecting into the
guts of the phone. Perhaps an old ARRL handbook or FM & Repeaters Handbook
would have information about how to hook one up, but there may be a simpler
way.
Just connect the two leads out of the phone through a series resistor (maybe
620 Ohms?), to a DC power source. The phone company used 48 volt batteries,
but it will probably work with as little as a 9 volt transistor battery.
Connect a series capacitor from the junction of the resistor and the phone, to
a potentiometer, and the output of the potentiometer to your audio input.
When the phone is on-hook, the phone line is disconnected, so you might want to
bypass the hook switch. When off-hook, the phone's earphone and microphone are
connected, so you may want to disconnect them.
Good luck!
73, Fred, K4DII
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