Kenwood interface for visually impaired radio amateurs

The interface, ready to be mounted to the radio.

This article describes an add-on for modern Kenwood transceivers to allow visually impaired operators to use these radios with a VS-3 or VGS-1 voice synthesizer. I built this interface for Adrian PA0RDA (using a TS-2000), but I’m almost sure that more visual impaired radio amateurs will be interested. The add-on is easy to build, most of the work is mechanical while the electronics are easy.

Most mobile and desktop radios of Kenwood have a voice synthesizer option. The voice synthesizer provides accessibility features for visually impaired radio amateurs, like announcing the frequency, memory channel, signal report or selected menu item and their values. To operate the VS-3 you need “programmable funtion keys” (PF1, PF2, etc). You need at least two of these: one to announce the frequency of memory channel, and another one to get the signal report. Unfortunately the TS-2000 has only one PF button. One solution is to use the Kenwood MC-47 microphone, offering 4 PF buttons. A more generic solution is this interface, allowing you to use any Kenwood compatible microphone or head set.

Circuit of the interface.

The interface is a small box, series connected with the microphone. At the front it has 4 buttons and a microphone connector. At the rear side is a cable, which can be plugged into the radio.

Tjalling PE1RQM built the first version for Adrian PA0RDA to operate his TS-2000. He built a small box out of copper clad. The box was not mounted anywhere, so when moving the microphone the box simply followed its movements. After a couple of years the box collapsed due to bouncing around the desk all the time. So Adrian needed a more solid one.

I bought a small aluminium case (Fixapart G102) and drilled two holes in the bottom, these holes align with the existing screw holes on the left side of the TS-2000. I drilled more holes for the buttons, microphone connector and cable mount. Then I painted it black and went listening to the Rolling Stones. The next day the paint was dry and I finished the box by placing all components, soldering the resistors to the switches and wiring all connections.

I selected higher quality buttons to ensure years of smooth operation. For the microphone cable I reused an old VGA computer cable, which has enough wires, both shielded and unshielded; I used a shielded wire for the microphone signal. The VGA cable also has an integrated RF shoke, keeping all the RF out of the radio.

Notice: I did not draw the circuit. Just search the web for “kenwood mc-47” and you can adapt its circuit (four switches, two 22k resistors and two 100k resistors).

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  1. Nice box.
    As a member of the CGR Commissie Gehandicapte Radioamateurs, i think this is a good accessoire.


    Eric-Jan PA1EJ

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