Cat5 patch lead for Icom remote head lead.

Picture this: I have an Icom radio that has a remote head connected to the body by the (supplied) patch lead that is about 6" (150 mm) long. I want to move the head of the radio closer to the computer, where I am operating, but don't have the OPC-1155 seperation cable, which has a 6P6C modular plug (commonly known as RJ11, although the RJ(number) series includes the wiring scheme as well as the connector but I'm not going into that here) at each end. I do, however, have several computer network patch leads terminated with 8P8C modular plugs (commonly known as RJ45).

Those of you who have read about the mobile installation I did on my Toyota Yaris will know that I have previously made a microphone extension lead and also extended the head lead with computer Cat5 network cable. I have quite a lot of this cable and ready made patch leads, from a cheap purchase of a box of cables, and I wondered if I could adapt for use, rather than splice as I did in the car, one of the spare patch leads. So I got one out to have a good look.

Close examination showed that the connectors were the same height, same locking tongue, pin spacing etc. The only differences being the depth (not relevant) and width, 8 pins being wider than six (not rocket science!) see pictures below for comparision.

After checking the wiring (the RJ45s were molded to the cable) and noting that, pin for pin, the wires were correctly routed (the patch cable was not a cross-over) I pulled out my hobby drill and fitted the drum sanding attachment. A quick run down each side of the RJ45 plug and check for size.

I went as far as taking off the outer connections (pins 1 and 8) on the first end I sanded. This proved to be a bit much and on the other end I stopped with about 1 mm of insulation on each edge (there was no problem with alignment on the thinner end as the locking tongue centres the plug in the socket anyway). A slight bit of fine tuning to the body of the plug at the base unit end, as the socket is recessed and the plug body was too wide, and I was ready to test.

I plugged in the lead at both ends, pressed the power button and the radio sprang to life. A quick test call onto the local repeater got a good report for my audio (the microphone is plugged into the other side of the head so everything [except RF and Speaker] use the head lead) and further contacts later confirmed that audio quality was as it was before this modification.

If you look at the photo below you will see the relocated head with the "new" lead on the left and the microphone lead on the right.

Just another money saving tip from the home of someone with deep pockets, short arms and that impatient streak that says "I want it now!". I take no responsability if you try this and it doesn't work. It did for me and my Icom IC-2725. It should for other radios that use similar connectors but check pin for pin to ensure that the correct pins are connecting.

How long did it take? I started looking at the plugs about an ¾ of an hour before I was on air testing, so no time at all really.