[Elecraft] K3 - Microphone Connector

[Roger de Valle]

This is a question about the K3 Microphone connector, is it correct to
assume that the UP and DOWN operations are achieved by momentarily grounding
the pins the corresponding pins?

 

Secondly there is a pin designated FUNCTION, I cannot see any description of
the purpose of this pin in the manual, can someone enlighten me as to what
this pin is used for. 

 

I am just interfacing a boom microphone so I thought I may as well
incorporate UP and DOWN buttons onto the interface box along  with a PTT
switch.

 

Regards Roger VK3ADE.