Kenwood tm-231a antenna questions (and more)

Hey folks, it’s been a while.

Recently I was walking around an estate sale and saw this little kenwood Tm-231a for $8, so I gave it a try. I did some googling and found old threads and documents about replacing the battery (which I did), and installing a 2n914 (I think) diode in order to transmit above 149mhz or something, along with clipping a wire. Not sure why I bothered since this radio is so old, but I’ll get to that.

So here is what I’m trying to figure out. I have this massive whip antenna, and a short stubby looking antenna. I think these are CB antennas which I see a lot of arguing online about. I don’t care to open up the debate on if you can use one for transmit, but I was curious if they would be any good for receiving.

Here’s a couple reasons why I don’t care about transmitting. For starters, I don’t have a license, however I work for my state and have to use radios for work. We use DCS codes so this radio will never be able to communicate with any of our radios, but it can hear things which is just fine. I am wanting to either have this in my personal vehicle for fun, in my residence as a monitor, or in the other half of the office. We will find a place for it.

Another side note here is that I keep a junky little Baofeng UV-82 and use it all over the state. Keeping the kenwood on and the baofeng on, I have always gotten the Baofeng to pick up whatever while the Kenwood has not. If someone keys up their radio very close to the kenwood, it will respond and show a signal. So I know it has life.

Thanks! Any feedback about the issue or general stuff about this radio would be appreciated.

Another thing that’s kinda odd. I keyed up the radio and the display was dimming and there was a pulsing/popping. Kinda odd. This does not happen on some frequencies.

This happened when trying to mess with the lock slider on the back of the hand piece. Guess it doesn’t matter much since I want a monitor not a broadcaster .

NICE Radio You Found There

1 Like

They’re not that old, pretty well specified and the dimming is because it was trying to transmit. It needs a simple antenna - 19.5" long and will be great.

So with the antenna, I have a “whip” cb antenna and a stubby cb antenna that appears to be wire-wrapped. Would these do fine for receiving or do I need to keep an eye out for a VHF antenna? I think I better understand the difference when looking at them, though I’m not 100% sure.

As for the dimming, this isn’t normal. It is rapidly pulsating and dimming while popping. It does make my baofeng radio light up sometimes when it does this.

I was wondering if maybe my car isn’t delivering enough amps for it since I’m running it off the cigarette lighter in a car from 1989. When indoors I was using a desktop computer power supply just as a test, and it didn’t do this. My main worries were I blew something, or that the antenna wasn’t a proper load and could blow something.

Figured out how to share a video of what it’s doing.

I might bring it inside and hook it up to a proper power supply. It bugs me it doesn’t work even though it really doesn’t need to.

Doing a ton of internet digging I finally found someone with a nearly identical issue. They were running two “radios” off a power supply on a boat. The amperage the power supply could provide was too low and unable to provide the needed current.

So what I need to do is bring this thing inside if I have time tomorrow and hook it up to my power supply (don’t know the amps but I can maybe figure it out), and see if that’s the issue.

This radio is ran off the cigarette lighter. Every radio I’ve had like this in a state vehicle was hard-wired by the radio shop so, and in newer vehicles. Since I won’t be broadcasting i should be able to get away with the cigarette lighter.

My next assignment is at a place that uses UHF so this radio may be no use, though there will be plenty of boats around so they may be on VHF. Not too sure what frequencies they use but I guess it’s not too important.

For somebody who doesn’t want to transmit, you’re doing quite a bit. Two issues - one could be the lack of available power. Try the radio on low power and see. The other thing is you must NOT transmit without a proper antenna. It will have a terrible match, and worse, the RF often gets back inside the radio. If you want to transmit, sort the antenna. ANY CB antenna is about as good as a damp bit of string stuffed in the hole - and it can kill the radio. Boats are going to be on marine band - so 156-162 in the main.

Thank you. I’ll try lower power and see what it does. Mainly I just like having equipment that’s in order, and do a bit of junk trading with the locals. My thoughts mostly are if I can use it as a monitor that’s great, if I can prove it works and is in order I can always trade it with someone for something I can use.

I guess it’s more of a toy than anything. For work I have been allowed to program these baofengs to be used. I’m frequently around water and dangerous topography so the $500 state radio usually stays in my bag and the junky baofengs are what I beat up. Saves a lot on paperwork and such if something happens.

All is well doing some more testing. The radio still doesn’t pick up anything so I’ve yet to hear a broadcast through it. Kinda frustrating since my baofeng sitting next to it can pick up the EMS broadcasts and the weather station.

Did you sort a decent antenna?

Not yet, so that should be my main problem. I’m not too sure what to get and what price range to look at, though I want to go as cheap as I can.

I’m waiting until I can check out a local junk man I know. I have seen a few antennas at his place and have seen a basic short wire antenna that at least looks like the vhf antennas I see online. If there’s no make and model on it then I don’t know how to tell.

Somewhere at my parents house there was a antenna I’ve also been looking for. I’d imagine my dad got it from his dad, who had ham stuff. As a kid I would unscrew the antenna from the base and put it back on, though last I saw it it has no antenna on it. It may be lost but regardless I’m looking locally first.