Wednesday, July 29, 2020

SVL: Audio Cable for FRS radio

When I last played with connecting an FRS radio to the computer, I didn't connect the radio directly to the computer, because a) I didn't know what the pin-out of the radio was, b) I read that connecting line out to microphone input can blow the microphone circuit, and c) I didn't have enough time to test things out.

In the meantime I learned that connecting output to microphone input works if you are careful with volume levels. I also found out what the pinout of the headset plug in my Motorola Talkabout EM1000R is. Hence, tonight I sat down and butchered some cables. The wiring is very simple:

The Motorola EM1000R FRS radio has a 2.5mm plug with a shorter than normal shaft, i.e. only 2.5mm plugs specifically designed for this (and similar) radio fit. I solved that problem by cutting the plug off my crappy and uncomfortable Motorola headset purchased years ago. The photo below shows the cable in operation with separate microphone and stereo 3.5mm plugs. The wiring works similar to the 4 pole TRRS plug: Ground at the shaft, and signal (Mic or Left) at the tip of the respective 3.5mm plug.

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