[Elecraft] PTT Signal Question

[Kevin Shaw]

I'm in the process of designing a USB interface board for my K2 and I have a
technical question concerning the "/DOT-PTT" signal in the K2. The signal
goes into Port D of the PIC processor. PTT is grounded when the microphone
is keyed yet I don't see a pull-up resistor on the signal. I believe Port B
of the PIC has internal pull-ups but not Port D. Is there a pull-up on that
signal somewhere on the schematic that I'm missing?

 

Thanks,

 

Kevin

N8IQ