Radio Programming Interfacerpi01.jpg (68934 bytes)


It is common practice that synthesised channelised commercial radio transceivers   are programmed by a PC application. Connection is made by a standard RS-232 COM port on the PC, but many radios use a TTL/ CMOS interface levels.

Of those that use TTL interface level, they fall mainly into two groups, those that have a common pin for transmit and receive data (such as the ICOM CI-V interface) and those that have a separate transmit and receive pin.

Some radio interfaces provide power that can be used to power the adapter unit, others do not.

This article describes a generalised unit for interfacing a transceiver's TTL/CMOS interface to RS-232.

Use this information entirely at your own risk, NO RESPONSIBILITY WILL BE TAKEN FOR YOUR USE OF THIS INFORMATION.



The interface should:

I have chosen to not try and power the adapter from the RS-232 interface. This could have been done, but could be unreliable for some serial interface implementations.

Target models

Adapters for other models have been developed, see below.


The unit requires a rectifier/filter, regulated 5V power supply, RS-232/TTL level converter for two signals in both directions, appropriate connectors for the computer, radio, and power.

One of Don McKenzie's Simmstick boards is a good match to the need, providing accommodation for the rectifier/filter, regulated 5V power supply, and MAX232 chip.

I have used a DB25 for the RS-232 connection, you could use a DE9 but I chose the DB25 for ease of connection of a break out box for troubleshooting. If you want to use a DE9, you could use the board's provision for a DE9.

I have chosen a DA15 for the radio side connection to provide plenty of pins for the planned signals and power, and to extend the 'spare' drivers in the MAX232 for later flexibility. There are still some pins left vacant. Again DA15s are easy to get, and easy to solder with simple tools.

To facilitate the common transmit and receive pin, I have provided an 'open collector' Tx Data connection on pin 4 of the DA15. This is not a true open collector, it is connected via a diode to the TTL output of the MAX232, so will not pull  quite as low as a true open collector, but reliably pulls the pin down to a valid TTL logic 0 state.

Pin 11 of the DA15 provides for supply of power to the adapter through a series diode to prevent backfeeding the readio interface if a power source was feeding power to the dedicated AC/DC input jack. The AC/DC input jack is similarly protected by the bridge rectifier.

Table 1: DA15 wiring to DT207 board

DA15 Notes SIMM connector MAX232
1 Ground 9  
2 Tx Data (R2out) 12  
3 Rx Data (T2in) 13  
4 Tx Data (open collector). Wire a diode anode to this pin, cathode to DA15,pin 2.    
5 T1in   11
6 R1out   12
7 R1in   13
8 T1out   14
9 +5VDC 7  
10 Unregulated +VE 4  
11 +DC input 8 - 20V Wire a diode anode to this pin, cathode to DA15,pin10.    


Table 2: DB25 wiring to DT207 board

DB25 Notes DT207 DE9
2 Tx Data 3
3 Rx Data 2
6,8,20 DSR/CD/DTR NC
7 Ground 5


The programmer is housed in a die cast aluminium box (Dick Smith H2211 fitted with four stick on rubber feet). The board is supported on two 10mm long 3mm threaded hex pillars, with countersunk screws from the box exterior. The lid was milled for the DB sockets and holes drilled for the isolated power input jack and LED. Artwork for a simple label was quickly knocked up and a Quickmark label made to finish the unit. A PDF format copy of the artwork is available here.

Assemble the DT207, but do not install DE9-F, J1, SW1, R2, the on board LED, or the links, they are not needed. I socketed the MAX232 as a serviceability feature, it doesn't enhance reliability, but it does make it easier to fix in the field if you let the smoke out of the MAX232. Connect wires from the board's LED holes, J1 holes, DE9, SIMM edge connector, and the underside of the MAX232 to the panel components as detailed in Tables 1 and 2. Connect the case to the ground rail.

rpi02.jpg (89659 bytes)

Radio Programming Interface - internal view

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DT207 board


rpi03.jpg (86895 bytes)

At work in the crowded space of a small boat.




RJ45 Colour / Notes DA15
1 Rx Data - Brown 3
2 Tx Data - White/Brown 2
3 Control - Orange 1
5 9VDC - Blue 11
7 Gnd - Green 1
The RJ45 plug may be plugged into the mic jack, and into the remote jack on the transceiver configured for remote heads.

Colours assume T568A RJ45 configuration.

This configuration should work on PRM8020, PRM8025.

I have noticed some problems using this adapter in the self powered mode on the transceiver RJ45 of a dual mode (trunk/conv) PRM8030R. It worked fine on the remote head, and seemed fine when the RPI was  externally powered.



3.5mm stereo plug Colour / Notes DA15
sleeve Braid 1
ring White 3,4
tip NC NC
The 3.5mm stereo plug is plugged into the ext speaker socket.

OPC-646 - I have researched programming the IC-207 and IC-2710. It seems that they are programmed via the port used to connect the remote head. This port uses a proprietary connector which I think will be expensive to obtain (one source in the use looks like nearly A$200 by the time it is landed here). More as it unfolds.


TAIT 2000

RJ12 Colour / Notes DA15
1 Brown (Blue) - Tx Data (T1out) 8
2 Yellow (Yellow) - Gnd 1
5 Black (Black)  - Rx Data (R1in) 7
6 Orange (White) - DC 11
NC Tx Data (R2out - T1 in) link 2,5
NC Rx Data (R1out - T2in) link 6,3
The TAIT radio has RS232 levels at the RJ12 but benefits from the cascaded RS-232/TTL/RS-232 drivers.

Colours are for two common cable types for USOC application.



RJ12 Colour / Notes DA15
4 Red - Gnd 1
2 Yellow - Data 3,4
3 Green - +9V DC 11
This uses Yaesu's RJ12 pin numbering which is the reverse of USOC RJ12 numbering. Colours are for a common cable type for USOC application.

This should also work for the FT2600M

The same DA15 config should work with a FT50, VX1R, VX5R with the data connection made to the ring of a normal 3.5mm stereo jack, and ground to the sleeve (I am told that you don't need the special 4 pole plug for programming).


The information on the Radius is UNTESTED.


  Colour / Notes DA15
GND / pin 5   1
Bus+ / pin 2   3,4


Sourcing the parts

The DT207 PCB is available from Dontronics. The 78L05 can be hard to find, Dontronics should have those, otherwise use a 7805 in a TO220 package.

All the rest of the parts are very common and should be easy to find.

Reference data


rj45.jpg (45460 bytes)


wpe1.jpg (16221 bytes)


I would like to acknowledge the valuable assistance of Justin Albury.

© Copyright: Owen Duffy 1995, 2021. All rights reserved. Disclaimer.