Kenwood TH-D72 Frequency Hoping and Switching Weirdness.

Do you own a Kenwood TH-D72 and wonder why sometimes it jumps to the weather stations, starts scanning your presets or some other frequency change that you just can’t seem to figure out? This article will tell you how to fix it, along with some theories as to what is causing it.

 

First, let’s start out by saying I have one of these radios and love it. I use it for FM on satellites, I have done packet (APRS) through NO84, FS3 and the ISS. I have also had my longest QSO ever on it. So make no mistake, I love this little radio and wouldn’t trade it for the world.

 

So what causes this frequency / band hoping? Not sure but I do know it involves two things

1. Headsets or earbuds where the plug has 4 bands vs 3. Since it is almost impossible to buy earbuds or headsets for your smartphone without this 4^th band, you most likely have 4 bands on yours. As a matter of fact the only place I can get earbuds with 3 bands on the plug, I took from an airline flight I had a few months ago. (Thanks Delta) Here is a picture showing the different types of plugs.

2. You are using some type of Kenwood / Baofeng mic / headset adapter. This adapter has the 2.5mm male plug and the 3.5mm male plug built into the same housing and both plug into the side of the radio.

So what is my theory as to what is happening? I believe that the 4 band male plug is shorting out somewhere in the Baofeng adapter causing the D72 to, technically speaking, “freak out”. It may be part of some type of protocol to control the radio with a computer, or it just might be a short. Either way, it sucks when you are trying to use this set up and the issue happens. Oh and the fun part, the 4 banded plug just needs to be somewhere in your jumble of wires, it doesn’t need to be the one plugged into the radio.

 

So how do you fix it? First you have to understand that the issue has to do with the 3.5mm plug. With that thought there are a few ways to fix it.

1. Don’t use the 3.5mm plug. Buy one of these (2.5mm Splitter), and use the PTT to talk. This splitter is handy because it allows you to plug your recorder in on one side, and your headset on the other. The downside to this solution is that puts a lot of stress on the 2.5mm jack, so be aware of this…
2. Use the Baofeng adapter, but grind off some of the tip. Start small, but keep going until the issue is gone. Here is an example, but, I think I went too far. In other words, you want the support of the 3.5mm plug, without the issue rearing its face. Here is a pic, but do not start by grinding this much, start small, maybe just the first band, and see how it works. Once again you will need to use the PTT on the radio…

 

So there ya have it, do one of the above, and the issue will go away, and you can complete your QSOs without an issue.

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