Poor Range NX-700 2017 F250

[21Actual]

Hello all,

My work truck has a Kenwood NX-700 paired with what I believe is a Laird B1443 Antenna (would have to confirm). Simplex range is rather poor. Maybe 3 miles. Reception from our towers is fairly good, but I am having issues with transmit power (reaching towers) in that regard. (we operate on freq 160-161mhz)

I am unsure of how or where the 12v power source and ground have been sourced, or how many splice points there is. I am sure that it is not direct to battery +, and i suspect ground has been sourced somewhere under the dash. As for the antenna, again, I am unsure of how the coax has been routed, if there is tight coils,, or if there is any splices/extensions in the run. However the radio power feed and coax do emerge from the same location in the dash so possible interference being introduced to the coax. Also notable is antenna location. It is up high on the roof of the truck, however it is mounted with a drilled NMO mount fitted to an ACARI 01 third brake light mount ACARI 01 Series – ACARI Products
This mount is not bonded to the truck chassis is any way. It is fully insulated from chassis.

What I plan to do is run new 12gauge 12v and ground runs to power the radio, directly to battery +, fused at battery course, and ground where battery - is bonded to the truck chassis. Further, replace the antenna coax with a new cable and run separate and away from other wires as best as possible and not have any of the extra coax coiled up.

Looking for some insight from some experienced members on if this course of action is likely improve radio performance. (I need to confirm antenna model, I am not certain that is is infact a B1443, which I believe is a no ground place antenna) If the antenna is not a no ground plane antenna, will adding a braided bond between the ACARI aluminum body and the truck chassis be sufficient to provide the antenna with a ground plane?

It is frustrating that we have older steel body trucks in the fleet with the same radio and a magnet mount antenna slapped on the corner of the roof that are getting 3x better range.

Thanks for any help,
21Actual

 

[jim202]

Trying to not be a critic here but the antenna mount should not be mounted on what ever that fixture is there on the truck roof. The better place for it would be to drill the hole in the center of the roof where it belongs. But depending on the owner of the truck, they may not want any holes drilled.

My second attack is has anyone checked the SWR of the antenna from the radio? This will tell all about the condition of the coax cable, the connections and if the antenna is matched to the operating frequency. You will need an SWR meter and a short jumper to go from the meter back into the radio. On the other side of the meter you connect the coax cable that normally connects to the radio. You will probably need some coax adapters to make these connections.

The next test I would do is to check how the receiver is doing in receiving. Try a direct communication between you and another unit. Do this while standing still. First do it with the engine running and then do it with the engine off with the key switch only in the accessory position. Make sure your heater fan is shut off for both tests. Then do it again with the heater fan running.

This is a starting point to see if a finger can be pointed in the direction of why your getting such short range on your radio.

 

[mmckenna]

Yikes.

Acari mounts, mag mounts, unknown cable routing. Sounds like the installs were done by a mechanic to keep prices down.

I'm running an NX-700 in my work truck, a 2017 F-350.

A couple of things...

• Laird B1443 is a 5/8th's wave antenna. It requires a ground plane underneath it to work correctly. While the Acari mount may have a DC ground through the mounting screws to the body, that's different than a good RF ground plane.
• Having that antenna so close to the speaker/light probably isn't helping.
• Not sure what's up with the cable laid across the roof like that. Is that the coax, speaker or strobe wiring?

This doesn't look like an install that a reputable radio shop would do. Like I said above, looks like something a mechanic cobbled together.

Here's what I'd recommend:

Sure, check the DC wiring. But it's not necessary to wire the negative lead all the way back to the battery. If the strap from the battery negative post to the body is good, it's not necessary. Actually grounding the negative lead closer to the radio has some benefits. Having a short ground connection is good for RFI. I'll often run a separate strap from the radio chassis directly to ground if the radio is not actually bolted to the body in some way.
Check the DC positive connection. Ideally it -should- run direct to the battery positive or a larger connection to the battery. Avoiding any unnecessary splices/connections would be a good idea. It wouldn't be uncommon to find a larger gauge wire going to the positive battery post to a separate fused distribution block inside the truck to support the radio, additional lights, accessories, etc. I've done that on most of my installs.

If they'll let you, get the antenna off that mount. Have a reputable radio shop do a proper NMO install dead center in the roof of the truck. That will give you an ideal ground plane under the antenna, and will allow things to work best. Even 'no ground plane' antennas work better with a proper ground plane under them. That antenna, if it is what you think it is, absolutely needs a good ground plane underneath it to work right.

Check the SWR on the antenna. If this was a mechanics version of an install, it's possible they just cut the antenna according to the cut chart and called it good.

Check the coax cable routing. Make sure they'd didn't splice it, add adapters, etc.

That would be a really easy fix for a radio shop. Even having them do a proper NMO install would/should be less than $100, and would probably improve performance.

 

[mmckenna]

And that speaker stuck to the top of the radio with double sided tape…. In a collision, that could easily come loose and cause an injury. Double sided tape exposed to the heat on the dash isn't going to last long. Looks like they screwed the mounting bracket for the radio to the center tub there, wouldn't have been hard to mount the speaker the same way.

 

[N5XPM]

Jim and Mmckenna are providing great, basic corrective design assistance here.

If you elect to drill into the radio to hold the speaker securely, take the top of the housing off first and put bolts through from the underneath side of the radio housing into the speaker mounting bracket.

I have seen folks drill through the radio into the circuit board, then bring the radio in and ask why it doesn't work.

Other risk is using non-factory original bolts that are longer than original to connect the radio to the radio bracket, damaging the circuit board from the side.

 

[kayn1n32008]

Replace that 5/8 wave antenna with a half wave antenna for starters. Make sure the antenna is tuned. Check SWR. Make sure the radio is putting out proper power, and it’s properly programmed. Hazarding a guess, but I would almost put money down you’re involved in the rail industry, and while a 5/8 wave makes sense due to the 2MHz that rail occupies, the compromised ground plane really should eliminate the use of a 5/8, and should really be a 1/2 wave.

 

[MTS2000des]

Mounting the radio on top of the dash like that isn't going to make it live long baking in the sun, but can also become a propelled device when the passenger airbag activates.

This really looks like a "get her done" install and needs to be torn out, and done right from the ground up.

 

[GlobalNorth]

Since this is on your work truck, I assume that it belongs to someone else [person, LLC, corporation, etc.].

Do you have express written permission from the owner to alter the truck and the install? If not, leave it be and complain loudly enough to have the owner authorize a proper install from a qualified shop. If you alter it without express written permission, you can be disciplined by your employer just for "fixing it". If any problems come out of the "alterations", you could be liable.

I've seen what happened when someone decided to install a scanner on a mechanic installed - home brewed electrical fuse bus for two way radios and lights. It wasn't pretty and he got all the blame.

 

[mrweather]

If OP does railroad work (which appears to be the case) every movement/activity is governed by bulletins and orders, and not being able to effectively communicate with RTC due to a crappy radio installation becomes a serious health and safety issue.

 

[ab3ai]

I agree with GlobalNorth. I would find who did the install and go to there Supervisor. Two things I'd like to add are, I'd bet a pay check that is the antenna coax draped across the roof and it probably goes in through the door and that will crush the coax causing a high SWR. Second, the 5/8 wave antennas I've dealt with are field tuneable and need to be cut for RR frequencies. If you have a low SWR in the 150 range, the antenna has not been tuned. Where is the mic? Looks like the mic cord comes straight out and the mic clip has been removed from the dash. As with what everyone here has said, there is a lot wrong with this install, but don't take matters in your own hands with your companies equipment. I've seen people do that and and have literally burn the vehicle to the ground.