The PTT USB adapter uses an inexpensive Arduino circuit board (Pro Micro) to send keyboard commands via USB to a PC, Mac or tablet when pin#2 is grounded. When pin#2 is grounded, a keyboard Shift-F19 sequence is sent via USB so that RemoteTx sends a TX command to the radio. When pin#2 is released, a keyboard Shift-F20 sequence is sent so that RemoteTx sends a RX command to the radio.

Constructing a PTT USB adapter involves 4 steps.

1. Program the Arduino circuit board by uploading the provided sketch.
   This involves using the Arduino IDE software with the circuit board plugged in to a USB port to upload the program/sketch.
   Arduino software is found at: https://www.arduino.cc/en/Main/Software
   The RemoteTx PTT USB Adapter sketch code can be downloaded here: PTT USB Adapter Code
   (If you are unfamiliar or unable to do this contact RemoteTx. We may be able to help you do this remotely.)
2. Solder a female 1/4″ or 3.5mm plug socket to pins #2 and ground on the circuit board.
   If you have a socket that has 3 wires (most common), use the 2 wires that connect to the tip and sleeve part of the plug. Clip off the 3rd unused wire.
   
   
   
   Use a glue gun to secure the wire firmly to the circuit board (optional)
   
3. Plug a USB connector cable into the circuit board. USB Type-A (Computer) to Type-B micro (Arduino circuit).
   
4. Enclose the circuit board and connectors in 1/2″ or 3/4″ shrink tubing and then heat to shrink with a heat gun. The length of tubing should be about 3″.
   

Materials List:

1. Arduino Pro Micro Atmega32U4 5V 16MHz:  Link on Amazon
   
   
2. Socket adapter (1/4″ or 3.5mm) that can be cut and used as the socket.
   1/4″ Socket (2-wire): Link on Amazon
   
   3.5mm Socket (3-wire): Link on Amazon
   
3. Short 6″ USB cable: Link on Amazon