Cable

The cable for exchanging data between PC and VX-3 has been made according to the description on page sp7dpt.qrz.pl, originally intended for VX-7. The project is based on MAX232 chip, which converts signals between RS-232C (+/- 15V) and TTL (0/5V) standards.

Schemat

 

The communication interface uses a serial port of a PC and VX3's external mic plug. A 4-pin mini-jack or jack 2,5 with CT-44 adaptor may be used:

wtyk dla VX-3

 

This device works properly with my laptop, however I can't guarantee that it will work with other PCs or COM <-> USB adaptors.