Kenwood: Confusing TM-281A Programming/Possible Antenna Issues(Mobile)

Joined
Oct 10, 2016
Messages
23
Hi everyone. I recently bought myself an upgrade from my first radio, a Baofeng UV-5R, to a Kenwood TM-281A. I already had a Nagoya magnet mount antenna on the roof of my truck that I used for my Baofeng HT. So I bought the TM-281A and an adapter cable so it would connect to the antenna cable. Within the first couple minutes of installing it in my truck I was able to hit my local repeater and TX/RX was 5x5x5. So the following night and from thereafter I have had nothing but problems. I cant reach anyone, incoming TX is picket fending REAL bad when I drive, very poor signal in general. Lots of static. I have tried switching from tone to CTCSS, I have tried VFO and MR mode and Ive even done a hard reset on my TM-281 and manually reprogrammed the local repeater 3 times now. I havent checked in a while but 52 simplex worked when I tested it using both my TM-281 and my Baofeng UV-5R. Then again, they were 5 feet apart.

So I am at a total loss here. Is my antenna fried? Is my radio? I dont understand what changed and Im pretty frustrated with it. I dont have an SWR meter and the ONLY way to get local help is to sign up for a yahoo email and join a very clunky and outdated "reflector" page because none of the local hams will embrace the local amateur radio clubs facebook page. Also obviously I cant get anybody on the radio. Whats even worse is my UV-5R recently crapped out on me and I wasnt able to TX, only RX. Heres some extra details that may or may not help:
-I am powering the TM-281 using a Blue Seas System 12v 12 bus fuseblock that has several other electronics tapped into it
-I have both ground wires and hot wires from the fuse block all zip tied together
-At one point the SMA connector on the antenna came loose so I shoved it back together, everything worked fine so I used electrical tape to keep the connection tight. I know some of you will focus on this but please try not to fixate.
-I have not tried programming with a computer yet. I have the MCP-01A software and driver installed on my laptop but I cant afford a $100 cable so I bought a cheap $10 one off ebay. I am seriously concerned about how complicated the software and driver is to deal with to set up correctly before running it and now I am afraid to use this cable.

Please let me know what other information you may need. THANK YOU!
 

AK9R

Lead Wiki Manager
Super Moderator
Joined
Jul 18, 2004
Messages
6,482
Location
Central Indiana
Power and antenna. Those are the things you should concentrate on for now.

How is the Blue Seas distribution block connected to your vehicle's electrical system? Direct to the battery with heavy gauge wire?

By your own admission, it sounds like the antenna cable is suspect. Go to The Antenna Farm's website and order a NMO magnet mount from Larsen, Laird, or PCTel Maxrad. Also order a Larsen, Laird, or PCTel Maxrad quarter-wave VHF NMO-mount antenna. Some of the listings are for "no tune" quarter-wave antennas that cover 144-152 MHz and that would be a good place to start. In most urban and suburban areas, a quarter-wave antenna will work just fine. Do not cheap out on the antenna or the mount. Stick with the name brands that I mentioned.

Once you address the power and antenna, then we can work on other questions.
 

W5GX

Member
Joined
Aug 7, 2018
Messages
73
You say not to fixate on the loose antenna connection, but that's probably exactly where you should start. :p

Have you tried the Kenwood on simplex since the antenna fitting came loose? Can you hear it with the Baofeng?

Do you have another known-good antenna to try? You can make a quick dipole with a UHF panel connector and copper house wiring, your you can use a length of coax.

Investment numero uno for you should be a SWR meter - but transmitting on low power for only a second or two should be workable to confirm.
 
Joined
Oct 10, 2016
Messages
23
Hey thanks for the replies!
-The power distribution block is connected to my battery using 0 gauge wire, pretty short runs of it too I should add.

-The antenna cable connection is not loose, it was just "repaired".


-I do not have another antenna.

-The radio comes in perfeftly clear on 52 simplex, but thats with the radios only a few feet away from each othher.
 
Joined
Oct 10, 2016
Messages
23
Sorry for the weird reply therr. Doing this on my phone while also on the phone with PayPal customer service haha. I will look at getting an SWR meter and I will check out Antenna Farm. Thank you!
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,828
Location
SNCZCA01DS0
I already had a Nagoya magnet mount antenna on the roof of my truck

…………..

-At one point the SMA connector on the antenna came loose so I shoved it back together, everything worked fine so I used electrical tape to keep the connection tight. I know some of you will focus on this but please try not to fixate.
Yeah, two red flags. Simply pushing the connector back on the coaxial cable is likely not going to fix it. If it came apart, it's because it likely was not assembled correctly at the factory. Properly installed connectors shouldn't come apart.
Using an adapter is less than ideal, also.

Stick with known brand names. As W9BU said, get a good mount and antenna, you will not regret it.
Ideally you want a permanent NMO mount on the roof of your truck, but for now, here's a quality NMO mag mount that is built well by a quality manufacturer:

And get yourself a basic VHF 1/4 wave antenna, again, stick with known good brand names, ditch the cheap Chinese antennas:

That antenna will need to be cut to work on the 2 meter VHF band, but that's easy to do, the antenna will come with a "cut chart" that you can use. 1/4 wave antennas are very broad banded, so you can get them really close with just the chart. When you get an SWR meter, you can double check, but after 30 years of doing this, the cut charts are pretty much right on.
 
Joined
Oct 10, 2016
Messages
23
Yeah, two red flags. Simply pushing the connector back on the coaxial cable is likely not going to fix it. If it came apart, it's because it likely was not assembled correctly at the factory. Properly installed connectors shouldn't come apart.
Using an adapter is less than ideal, also.

Stick with known brand names. As W9BU said, get a good mount and antenna, you will not regret it.
Ideally you want a permanent NMO mount on the roof of your truck, but for now, here's a quality NMO mag mount that is built well by a quality manufacturer:

And get yourself a basic VHF 1/4 wave antenna, again, stick with known good brand names, ditch the cheap Chinese antennas:

That antenna will need to be cut to work on the 2 meter VHF band, but that's easy to do, the antenna will come with a "cut chart" that you can use. 1/4 wave antennas are very broad banded, so you can get them really close with just the chart. When you get an SWR meter, you can double check, but after 30 years of doing this, the cut charts are pretty much right on.

Great thank you. I am looking at their website now and I am confused about the difference between these antennas:




I would prefer to have one in a black finish, but these are all roughly the same price and I cant find any info on what the differences are between them besides design. They dont even mention if they are 1/4 or 1/2 wave. Im assuming theyre 1/2 wave since they are all supposedly around 35" long. Would that be a fair assumption? I was thinking about getting a 1/2 wave and instead of putting it on the roof of my truck, I would instead mount it on the bed. That would leave around 1.5 feet sitting behind the cab of my truck. Will that cause problems are will I lose any advantage that having a 1/2 wave would give me over a 1.4 wave antenna? Should I just stick with using a mag mount and putting a 1/4 wave on my roof?
 

W5GX

Member
Joined
Aug 7, 2018
Messages
73
The only differences are if you want black, chrome with spring, or chrome without spring. With a 35" whip, you're in the 1/2 wave ballpark for 2m, 1-1/4 for 70cm - you'll want to adjust that further using an SWR meter, but likely it won't need any trimming.

If you want to mount on the bed cap, you'll need a much longer whip - think 5/8 or longer, as you'll have to get higher than the cab, target for 1/4w or more.

If you get too close to the cab, it will make your SWR readings inconsistent.

Another option would be to get a real flexible whip - a 1/4w on the cab roof would get great performance. A Comet SSB-1 would be an excellent choice.

 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,828
Location
SNCZCA01DS0
Yeah, Chrome, Chrome with spring, black.
Those are all dual band antennas. Nothing wrong with that if you think you'll eventually need a dual band antenna, but for your Kenwood TM-281, you only need a VHF antenna.

They dont even mention if they are 1/4 or 1/2 wave. Im assuming theyre 1/2 wave since they are all supposedly around 35" long. Would that be a fair assumption?
1/2 wave on the VHF side, something else on UHF, probably a cophased multiple of 1/4 wave on UHF, and that will want to see a ground plane.


I was thinking about getting a 1/2 wave and instead of putting it on the roof of my truck, I would instead mount it on the bed. That would leave around 1.5 feet sitting behind the cab of my truck. Will that cause problems are will I lose any advantage that having a 1/2 wave would give me over a 1.4 wave antenna? Should I just stick with using a mag mount and putting a 1/4 wave on my roof?
Putting a VHF or UHF antenna directly behind the cab will result in a number of issues. The signal (both receive and transmit) will be shielded by the cab. If it's in close proximity, it's also going to de-tune it.
If you really need to have it down on the bed rail, move it as far back as you can. It's still going to be less than ideal, you want these antennas up high on the roof of the vehicle for ideal performance.

I'd put the 1/4 wave mag mount on the roof. That's going to work very well, better than on the bed rail. It'll be up high and in the clear, and if in the center of the roof, it's going to give you the ideal ground plane.

A 1/4 wave VHF antenna will be 3/4 wave on 70cm, so it'll work fine on UHF if you need it in a pinch. I ran a dual band radio that way on an older truck for years. SWR was nice and low, but the radiation pattern is a bit high on the UHF side. It'll work, though.
 
Joined
Oct 10, 2016
Messages
23
These are all excellent replies. Thank you all for holding my hand through this! I ordered an SWR meter earlier today and I will narrow my search to mag mounted 1/4 wave antennas for the roof like the Nagoya I am currently running.
 
Joined
Oct 10, 2016
Messages
23
I am going to shop around for an antenna setup and once that is installed and I get my SWR meter on it, I will report back and see if my issues still persist.
 
Joined
Oct 10, 2016
Messages
23
Exactly what type of antenna do you have currently? If your current model is not capable of the higher RF output of the 281, you may have fried it.
I cant recall nor can I find the exact antenna anymore, but it is a mag mount Nagoya with an SMA connector on the end of the cable to screw directly into an HT. It was supposed to be rated for 80 watts.
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,828
Location
SNCZCA01DS0
These are all excellent replies. Thank you all for holding my hand through this! I ordered an SWR meter earlier today and I will narrow my search to mag mounted 1/4 wave antennas for the roof like the Nagoya I am currently running.
What brand/model SWR meter did you purchase? Is it one that is rated for VHF use? CB SWR meters will not accurately read other bands.

And I'd really strongly suggest sticking with one of those name brands that were suggested. The cheap Chinese antennas/mounts can have some issues.

-Don't buy a $150 radio and hook it up to a $20 antenna and expect it to work like a $150 radio. Your antenna is the most important part of the radio SYSTEM. You need to look at this as a complete system and purchase accordingly. The Larsen and Laird antennas are good choices, high quality and known good performers. Avoid the hobby/scanner/ham grade antennas.
 
Joined
Oct 10, 2016
Messages
23
What brand/model SWR meter did you purchase? Is it one that is rated for VHF use? CB SWR meters will not accurately read other bands.

And I'd really strongly suggest sticking with one of those name brands that were suggested. The cheap Chinese antennas/mounts can have some issues.

-Don't buy a $150 radio and hook it up to a $20 antenna and expect it to work like a $150 radio. Your antenna is the most important part of the radio SYSTEM. You need to look at this as a complete system and purchase accordingly. The Larsen and Laird antennas are good choices, high quality and known good performers. Avoid the hobby/scanner/ham grade antennas.
I got that antenna for m $30 Baofeng HT. I didnt buy it after I bought my Kenwood. But Laird also makes $12 2m mag mount mobile antennas so Im not sure I see your argument there.
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,828
Location
SNCZCA01DS0
But Laird also makes $12 2m mag mount mobile antennas so Im not sure I see your argument there.
Got a link? If you can get a genuine Laird VHF antenna -and- a genuine Laird NMO magnetic mount with cable and connector for $12.00, I'd love to know. Usually your looking at $30 for the mag mount and $15 or so for the antenna.

Just beware of cheap knock-offs.

There is a big difference between antennas, and if you got your hands on one and held it side by side with the Nagoya, you'd see what I mean. Laird, Larsen and the others stand behind their products. There's a good reason they are the brands you'll see in pubic safety applications. The guys who install this stuff know they can be trusted, and they know they'll last a long time. I've got 30 year old Larsen antennas still working/looking like new. All the old ham grade antennas I had from the late 80's/early 90's are all long since in the trash.
 
Joined
Oct 10, 2016
Messages
23
Got a link? If you can get a genuine Laird VHF antenna -and- a genuine Laird NMO magnetic mount with cable and connector for $12.00, I'd love to know. Usually your looking at $30 for the mag mount and $15 or so for the antenna.

Just beware of cheap knock-offs.

There is a big difference between antennas, and if you got your hands on one and held it side by side with the Nagoya, you'd see what I mean. Laird, Larsen and the others stand behind their products. There's a good reason they are the brands you'll see in pubic safety applications. The guys who install this stuff know they can be trusted, and they know they'll last a long time. I've got 30 year old Larsen antennas still working/looking like new. All the old ham grade antennas I had from the late 80's/early 90's are all long since in the trash.

I never said it was a separate antenna and mag base. I said they sell a mag mount 2m mobile antenna for around $12. Thats on theantennafarm.com. I was just looking at them today but theyre not what Im looking for.
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,828
Location
SNCZCA01DS0
I never said it was a separate antenna and mag base. I said they sell a mag mount 2m mobile antenna for around $12. Thats on theantennafarm.com. I was just looking at them today but theyre not what Im looking for.
I'm not doubting you. I'm trying to make sure I'm not missing something. The only Laird $12.00 antennas I can find are not magnetic mount antennas, it's just the whip/base.

And I'm trying hard to steer you towards a standardized and high quality NMO mount, that way you can change the antenna easily without having to buy a new mount. As you become more active in amateur radio, you may want a dual band antenna, or something for a completely different band. The big benefit to sticking with the NMO mounts is that you can swap antennas all day long and not have to replace your mount.
 
Joined
Oct 10, 2016
Messages
23
I'm not doubting you. I'm trying to make sure I'm not missing something. The only Laird $12.00 antennas I can find are not magnetic mount antennas, it's just the whip/base.

And I'm trying hard to steer you towards a standardized and high quality NMO mount, that way you can change the antenna easily without having to buy a new mount. As you become more active in amateur radio, you may want a dual band antenna, or something for a completely different band. The big benefit to sticking with the NMO mounts is that you can swap antennas all day long and not have to replace your mount.
I appreciate that. Is there a reason I would want to go with an NMO mount over UHF if Im sticking with a magnetic base? I thought NMO was used for drilling holes or using some kind of mounting bracket. Do they swap out easier than a UHF connector equipped antenna and base?
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
13,828
Location
SNCZCA01DS0
I appreciate that. Is there a reason I would want to go with an NMO mount over UHF if Im sticking with a magnetic base? I thought NMO was used for drilling holes or using some kind of mounting bracket. Do they swap out easier than a UHF connector equipped antenna and base?
Good question.
UHF connectors get to be an issue as you go higher in frequency. While they are called "UHF", it's important to realize that back when they were designed technology was quite a bit different. Back in the 30's, UHF meant something different than it does now.
There's some good info here: UHF connector - Wikipedia

They were never designed to be an antenna mount, only a form of shielded connector for lower frequencies. Mechanically I'd not trust them for any large antenna.

UHF connectors are not, inherently, waterproof, so using them as an antenna mount is not the best option. Ham radio operators are the only ones that seem to like to use them as such. You won't see them used in any modern day public safety install simply because there are better and more reliable choices.

The NMO connectors, on the other hand, were designed from the ground up to be used as an antenna mount. They are good up beyond 1000MHz, and there is even a high frequency version that can be used up to 6GHz. They are waterproof. You can get them for through-hole installs. You can get magnetic mount NMO bases, and you can get bracket mounts, you can even get base station adapters. Just depends on what you want.

There is also a very wide range of antennas that will fit an NMO mount. If you use a UHF mount, you are pretty much stuck with the amateur radio antennas. If you use NMO, you can select antennas that will cover anywhere from the CB radio band well up to 6GHz, including cellular, WiFi, and satellite.

You can use whichever you want, your truck, your radio, your money. If you want the most flexibility and options for different antennas, you'll do better with the NMO mounts.
 
Top