Fender mount GMRS antenna and under seat power (pic heavy)

mikej

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I spent this afternoon installing a GMRS radio mount and running the antenna cable (and power) to under the passenger seat. I've seen bits and pieces of this on the forum, but I thought I'd make a threat that shows end-to-end how to do it in hopes it might be helpful for others.

Ingredients:
Topsy JL Fender Mount NMO Antenna Bracket
Midland MXTA24 Low Profile Antenna Cable
Midland MXTA26 6dB gain whip antenna
Midland MXT275 Micromobile two-way radio
Zip ties, zip tie anchors, one electrical butt connector, one electoral ring connector, spray paint

Pre-work: paint the antenna bracket so you don't have that shiny metal glinting out from your fender. Bonus points if you use touch-up paint to have it match your Jeep (I may go back and do this later, but I just used black matte spray paint I had laying around).

Take off your door driver door, this will make your life easier. You'll also want to drop your windshield (I did this with my hood open). It also turns out that the UHF connector on the cable is removable. I didn't, but it would make life easier to remove the connector, which means a smaller bit of cable to route. Only as I was writing this post did I realize this was an option.

Step 1: Install the Topsy antenna bracket per their instructions and thread the NMO end of the antenna cable through it. If you're anal, add a zip tie and an anchor.
i-F7bQFXx-4K.jpg


Step 2: Remove the driver side cowl, route the cable and add another anchor.
i-FXq2dM3-4K.jpg


Step 3: Pop the little plugs off of this foam piece that's under the windshield (this is why you dropped it).
i-qQs7BrV-4K.jpg


Step 4: Tug on the rubber bit to create a gap. Don't tug too hard, as there's some adhesive that would cause the foam to rip. Push the UHF connector end of the cable through the gap.
i-TGvC7KR-4K.jpg


Step 5: Pop off this little panel.
i-WWgpDNc-4K.jpg


Step 6: And route the cable down alongside the dash. Give it a push here and there to hide it.
i-tmLQZRs-4K.jpg


Step 7: Route the cable behind cables to get it under the dash. Remove the panel under the steering wheel (just pull on it and it will pop free) to make the routing easier. Add a zip tie to hold the cable in place.
i-7rdBKjt-4K.jpg

i-9kWk4nZ-4K.jpg


Step 8: Route the cable along the metal bar above the driver side foot-box. Add zip ties to hold in place.
i-LMbVwh6-4K.jpg


Step 9: Route the cable behind the center stack. If you pull the carpet back a little bit, you'll find a nice passageway (This is from the passenger side after I routed the table through).
i-TM2x7mk-4K.jpg


Step 10: Using the wrapped wire bundle already there as a guide, loosely zip tie the antenna cable along the base of the passenger footwell.
i-77qgHGh-4K.jpg


Step 11: Cut the power adapter off the power cable that comes with the MXT275:
i-6BmhqMs-4K.jpg


Step 12: Remove the plastic panel in the passenger footwell. Since I have the AUX switches, there's a nice ignition switched power source. I used a butt connector to attach the red wire for the radio and put a ring connector on the black wire. That ring connector goes to the bottom bolt in this picture:
i-3x8KnvM-4K.jpg


Step 13: Remove the bolts from this grey plastic that is at the base of the passenger door opening. You don't have to remove the thing entirely (I couldn't quite figure out how), but with some effort you can run power and antenna through it.
i-H93L2rv-4K.jpg


Step 14: Route the wires through this opening next to the passenger seat:
i-JnNpgmZ-4K.jpg


Step 15: With a little effort, you can route the wires under the carpet and out the opening for the under seat vents:
i-bLHNkRq-4K.jpg


Step 16: Pop the panel back in place and you'll see no wires:
i-6Kwkt49-4K.jpg


From here, it's just a matter of plugging in the radio. I'm saving that for another day, but it's all plug and play at this point. If you've gotten this far, you've done all of the hard work.





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Frezski

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Nice install! I ended up mounting the micro mobile under the passenger side dash where you snapped a photo on step 10.
 

Frezski

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oh and, if you haven't already done so, ensure you turn on both the unit speaker and mic speaker. I learned the hard way after I installed it on my Jeep, a year after I had already installed one on my truck. The mic speaker alone I found wasn't loud enough.
 
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mikej

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oh and, if you haven't already done so, ensure you turn on both the unit speaker and mic speaker. I learned the hard way after I installed it on my Jeep, a year after I had already installed one on my truck. The mic speaker alone I found wasn't loud enough.
Thanks for that! I'm wondering if I'll need to add an external speaker anyways with it mounted under the seat, but maybe having both speakers will be good enough. I'll give it a shot.
 

Frezski

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Thanks for that! I'm wondering if I'll need to add an external speaker anyways with it mounted under the seat, but maybe having both speakers will be good enough. I'll give it a shot.
Definitely give it a try. Amazing what reading the instructions will do! A few weeks ago in death valley, I noticed a big difference in the Jeep compared to the Utah trip last year in my truck. A lot less wondering on what was said. I want to say my Jeep has more rattling noises interior wise than my truck does.
 

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Nice install. But it seems more complicated than necessary. I used a Comet hood GMRS NMO mount that is held on by tension screws to the hood, and fed the cable through the factory rubber grommet in the firewall - located under the brake booster and where the clutch pedal would go if you had a manual instead of the auto. Just needed to drill a small hole through the grommet and feed the cable through and seal with RTV sealant, and run it to your GMRS receiver (I installed mine in the glove box next to a Uniden CB brain box.

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mikej

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Nice install. But it seems more complicated than necessary. I used a Comet hood GMRS NMO mount that is held on by tension screws to the hood, and fed the cable through the factory rubber grommet in the firewall - located under the brake booster and where the clutch pedal would go if you had a manual instead of the auto. Just needed to drill a small hole through the grommet and feed the cable through and seal with RTV sealant, and run it to your GMRS receiver (I installed mine in the glove box next to a Uniden CB brain box.
That certainly would have made the antenna run easier! Hopefully I never have a need to do this again, but if so, feeding the cable through that grommet is the way to go. Thanks for the tip!
 

Dkretden

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Has anyone tried to mount a GMRS antenna on the tailgate? I have the CoolTech mount for the tire carrier now and I am wondering if there is an antenna that might mount directly to it? That way, I could just remove the CB coax and put the GMRS cable in its place......
 

jeepdriver99

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Has anyone tried to mount a GMRS antenna on the tailgate? I have the CoolTech mount for the tire carrier now and I am wondering if there is an antenna that might mount directly to it? That way, I could just remove the CB coax and put the GMRS cable in its place......
I don't see why you can't do that. As long as the coax is 50 ohm it shouldn't be a problem. CB, ham and GMRS all use 50 ohm coax. As far as an antenna working on the tailgate, sure it will work. It might not be optimal but it does work. I put an antenna on the back of my 2018 JL (although not on the tailgave) for dual band ham and it does very well. One of the bands it covers can also be used for GMRS. I use it for that purpose. The antenna is the Diamond Antenna NR72BNMO Dualband Mobile Antenna.

IMG_2104.JPG
 

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I don't see why you can't do that. As long as the coax is 50 ohm it shouldn't be a problem. CB, ham and GMRS all use 50 ohm coax. As far as an antenna working on the tailgate, sure it will work. It might not be optimal but it does work. I put an antenna on the back of my 2018 JL (although not on the tailgave) for dual band ham and it does very well. One of the bands it covers can also be used for GMRS. I use it for that purpose. The antenna is the Diamond Antenna NR72BNMO Dualband Mobile Antenna.

IMG_2104.JPG
So a GMRS and CB antenna cable are the same? I didn’t know that. I will check what the cooltech cable is rated at. The switch from CB to GMRS here may turn out to be easier than I thought........
 

jeepdriver99

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So a GMRS and CB antenna cable are the same? I didn’t know that. I will check what the cooltech cable is rated at. The switch from CB to GMRS here may turn out to be easier than I thought........
The cable is just a "transmission line that consists of a tube of electrically conducting material surrounding a central conductor held in place by insulators" or in simple terms, a wire surrounded by a shield. It is used for a lot of different frequencies. CB is in the 27 MHz range and the GMRS is on the 467 Mhz range. They both use the same coax for the radios.
 

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RG-58 has a loss of about 14 dB in the 400-500 MHz range for 100 feet of cable vice 2-3 dB loss at CB frequencies. I use it for all my radios on the JLU.
 

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@jeepdriver99 I didn't think you were supposed to paint antenna mounts like that. Is it stainless steel? Or does it take a special paint? Or am I wrong on the antenna grounding. I was looking at a similar mount for a GMRS antenna, but I am just now starting to research it. Thanks for your input!
 

jeepdriver99

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@jeepdriver99 I didn't think you were supposed to paint antenna mounts like that. Is it stainless steel? Or does it take a special paint? Or am I wrong on the antenna grounding. I was looking at a similar mount for a GMRS antenna, but I am just now starting to research it. Thanks for your input!
I painted it to match the Jeep. When I put on the NMO mount, I scraped the paint off the bottom so it would give a good ground. I checked it with an ohm meter and it has a good ground.
 
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mikej

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I painted it to match the Jeep. When I put on the NMO mount, I scraped the paint off the bottom so it would give a good ground. I checked it with an ohm meter and it has a good ground.
I didn’t know about the paint issue. Good to know! I’ll need to scrape mine this weekend.

Can you explain how you checked it with an ohm meter?
 

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