Contents - Index - Previous - Next


Connection to the radio


Ready-made Cables

The radio is connected to the computer using a programming cable. The Links page of the website lists sources of ready-made cables that can be ordered over the Internet. 

The Yaesu data cable is the CT-142 which has an 8-pin mini-din at one end to connect to the radio and a 9-pin DB9 at the PC end. There is also the CT-140 which has an extra lead for connecting a TNC. Due to the non-standard cloning rate of 48000 baud these serial cables must be connected to a USB/serial adapter that uses an FTDI USB chip.


DIY information

The radio uses an unusual cloning baud rate of 48000 baud. The built-in serial port of the author's PC will NOT operate at that speed. During beta testing it was found that USB/serial adapters which are based on the Prolific chip do NOT work at that speed. Other makes of USB chip may also have problems. The ONLY USB/serial adapters the author has found that work straight 'out of the box' are those using FTDI USB chips.

If anyone finds another make of USB chip that works 'straight out of the box' then please contact the author to get this section updated.

The radio uses standard RS232 serial communications NOT TTL as do many other Yaesu radios. Here is a snapshot of receiving data from the FTM-350 - note that the polarity is Plus and Minus:




In the back of the APRS manual on page 35 there is a CT-142 cable diagram showing the pinout of the 8-pin mini-din on the radio and a 9-pin d-sub serial connector to the computer's serial port or a USB/serial adapter. Note that the diagram shows the connecting pins of the connectors, not the cable ends.

No level conversion circuit is required - this is a simple wire-to-wire cable connection. If you already have a FTDI based USB/serial adapter then this is a cheap and easy way to get connected.

Warning: At the bottom of page 35 of early APRS manuals is a diagram of the data socket on the radio. In the author's manual the numbering of the pins is wrong: the pin labelled as 1 should be 4; the pin labelled as 2 should be 1; the pin labelled as 4 should be 2. The revised manual issued with the release of firmware V1.2 has been corrected.

This is the correct pinout of the Data socket on the FTM-350




COM port selection

Selection of Com port number is done using the Settings menu. The program will remember the selection you make for the next time you run. 

There are two commands available - 'COM port Detector' and a pop-out called 'COM Port'. If you are certain about your COM port number then it is quickest to use the 'COM Port' pop-out. Otherwise use the 'COM port Detector' command. The following screen shows the result of detecting a Com port:



Follow the on-screen instructions to detect and set the COM port for your programming cable. Be aware that each USB socket on your PC may be allocated a different COM port number, so you may need to use this screen again if you use a USB/serial adapter and change your usual socket. You may not see your COM port if you are running a PDA hotsync program that has acquired all of the COM ports. Stop the hotsync program and try again.