Re: uBitx mic trouble: ptt always on #ubitx #ubitx-help

Vic WA4THR
 

If you have a voltmeter, monitor the PTT line before you plug in the mic and after, and when you press the PTT switch That will show whether the line needs an external pull-up circuit. In my case, there was a little bit of a load when the mic was plugged in and that dropped the voltage with only the internal pull-up resistor enough to be right on the threshold of detecting a PTT signal, so I just added an external resistor from 5v to the PTT line and that kept the voltage up when not keying. Another solution is to go into the software sketch and change the voltage level at which it detects the PTT switch. This is a bit unique to the uBitX, since it detects the signal in the Arduino. The BitX40, where I use the same microphone, just keys a relay when the switch is pressed.

=Vic=

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