Finer points on GMRS install

bucky

bucky

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So I’m finally getting around to installing my Midland MXT500 GMRS radio in my 05 TJRU. I’m mounting the radio on a Arizona Rocky Road overhead bar mount. I have dry fitted the radio on the bar and placed the bar on the roll bar. I need input on the wiring details. I pulled the glove box and loosened the fuse block. I see that there is a blank space for the #4 fuse but have not been able to figure out how to tap into it. Also from my limited ability to see the back how do I connect my wire to it? I can reach the fuse block without having to splice onto the factory pigtail. After unscrewing the fuse block I can’t get enough slack on the wire harness to get to the back. Is this the best way to get power or should I just bite the bullet and go through the firewall, splice the wires and go direct to the battery? I found the factory grounding point to the right of the fuse block so that should be easy. I’m planning on running the antenna cable through the firewall and mounting the magnetic mount with 6db antenna in the middle of the hood. I’m doing this because my area being the hot bed of crime I want to be able to pull the antenna when not in use. From what I’ve read the 6db antenna dies not need a ground plane. Your input is greatly appreciated. I’m doing a group run to Anza Borrego at the end of the month and would like to be able to communicate with the group.
 
I've installed numerous VHF & UHF radios for use by emergency services, as well as a hand-full of GMRS radios. I personally run a Kenwood TK880 UHF programmed for GMRS. I've always ran wire straight to the battery, as this is generally accepted as the method for optimum performance. I know some radios, particularly those 25w or less, are sometimes installed with an add-a-fuse in the fuse block, and some radio manufacturers even OK this method. But for the best power and performance, I've always done as I've been told and powered directly from the battery.
 
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I prepped my GMRS for power this weekend
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I got one of those 4 circuit Blue Sea gizmos as well - and I power my GMRS, Ham, CB, etc all from it. Where I differ from some is while I power a radio direct from the battery, I ground the return to the nearest available "good" ground. People will argue that you should run a separate ground wire back to the battery, but I'm not one of them. YMMV and all that.
 
Zorba said:
I got one of those 4 circuit Blue Sea gizmos as well - and I power my GMRS, Ham, CB, etc all from it. Where I differ from some is while I power a radio direct from the battery, I ground the return to the nearest available "good" ground. People will argue that you should run a separate ground wire back to the battery, but I'm not one of them. YMMV and all that.
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Sometimes I do the same re: locating the ground. But certain radios I've installed, especially some of the 100w VHF units, specify they need to be grounded at the battery. In those instances, I do what the manufacturer says. Sometimes I do it just because I'm already running the hot to the battery, might as well run a ground at the same time. But there's definitely been some times I just catch a good ground wherever I find it.
 
WVJeep304 said:
Sometimes I do the same re: locating the ground. But certain radios I've installed, especially some of the 100w VHF units, specify they need to be grounded at the battery. In those instances, I do what the manufacturer says. Sometimes I do it just because I'm already running the hot to the battery, might as well run a ground at the same time. But there's definitely been some times I just catch a good ground wherever I find it.
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Ya gotta do what you feel best. Its my opinion - and that's what it is, an OPINION - that running a ground back to the battery equals good is an old wives tale. Way I see it - rightly or not - its a potential antenna because there is NO way ANY wire running back to the battery is going to be a lower impedance than the chassis is.

I did "almost" the same thing with my winch. Grounded it to the chassis (and added a frame to engine jumper). However, there I *ALSO* ran the wire to the battery. Not because it made sense to do so from an electrical standpoint (it doesn't), but because its hard to make a reliable high current ground, and even harder to keep it reliable, esp. if its going to get wet. So I did both. Which, come to think of it, may very well be the reason some higher powered radios recommend the same thing - although 100 w is nothing by comparison to the ~4800 watts a winch may draw. I certainly would NOT recommend doing both with a radio - one or the other only, as strange and wonderful ground loops could happen. Doesn't matter with an electric motor, but electronics do NOT like ground loops!
 
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Zorba said:
Ya gotta do what you feel best. Its my opinion - and that's what it is, an OPINION - that running a ground back to the battery equals good is an old wives tale. Way I see it - rightly or not - its a potential antenna because there is NO way ANY wire running back to the battery is going to be a lower impedance than the chassis is.

I did "almost" the same thing with my winch. Grounded it to the chassis (and added a frame to engine jumper). However, there I *ALSO* ran the wire to the battery. Not because it made sense to do so from an electrical standpoint (it doesn't), but because its hard to make a reliable high current ground, and even harder to keep it reliable, esp. if its going to get wet. So I did both. Which, come to think of it, may very well be the reason some higher powered radios recommend the same thing - although 100 w is nothing by comparison to the ~4800 watts a winch may draw. I certainly would NOT recommend doing both with a radio - one or the other only, as strange and wonderful ground loops could happen. Doesn't matter with an electric motor, but electronics do NOT like ground loops!
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Agreed. I do what feels right at the time unless the radio is brand new and under warranty. I've seen dealers and manufacturers deny repairs/replacement over power source & grounding issues, so I err on the side of caution in those instances.
 
I run the Midland 275 - I believe it is the predecessor to the 500, and lower powered - wired through a dedicated circuit in the PDC. No issues at all, and clear as a bell. Perhaps the lower power helps?

I’m familiar with the reasoning for direct to the battery, but is there something about the GMRS which allows it to work OK not wired directly?
 
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While we're on the subject of GMRS installs, should I run a separate ground wire to the underside of the NMO mount?
 
Here is a thread I started about how to ground your radio.

Here is a thread about easy spots to pass through the firewall to the battery.

What kind of antenna are you running? That'll determine whether it needs a good ground plane. But if you're using a mag mount on your hood, you'll have a great ground plane anyway.
 
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Mount your antenna on the A-pillar with this mount,

https://www.amazon.com/dp/B089TB6CJJ/?tag=wranglerorg-20

Run the coax under the hood and thru the firewall. If you have a manual trans, there is a plastic plug in the firewall you can drill a hole and run the coax thru to the radio. That radio is a 50 watt radio, so it would be best to run power direct to battery with a inline fuse, with 10 gauge wire.
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bobthetj03 said:
Mount your antenna on the A-pillar with this mount,

https://www.amazon.com/dp/B089TB6CJJ/?tag=wranglerorg-20

Run the coax under the hood and thru the firewall. If you have a manual trans, there is a plastic plug in the firewall you can drill a hole and run the coax thru to the radio. That radio is a 50 watt radio, so it would be best to run power direct to battery with a inline fuse, with 10 gauge wire.
View attachment 488289
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Does he need to scrape away any of the powder coating to ensure a proper ground?
 
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bobthetj03 said:
Mount your antenna on the A-pillar with this mount,

https://www.amazon.com/dp/B089TB6CJJ/?tag=wranglerorg-20

Run the coax under the hood and thru the firewall. If you have a manual trans, there is a plastic plug in the firewall you can drill a hole and run the coax thru to the radio. That radio is a 50 watt radio, so it would be best to run power direct to battery with a inline fuse, with 10 gauge wire.
View attachment 488289
Click to expand...

Damn, now you went and made me spend money 😭 I've been thinking about adding a ghost antenna in that location for awhile.
 
I set up the radio and antenna on my wooden work bench to check it out. Was able to 2way with someone in a mt top 59+ miles from me with no repeater. I had Covid Fri-Sun and jury duty the last 2 days so hope to complete instal in the next couple of day. Weekend trip on the 19th so I have some incentive to get it done. Been on the list for a year. I have noticed while listening to it on the bench that no one uses their call sign here.
 
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