[ARCowboy]

Ohh hell I didn't know I needed to. Can you explain? I'm new to this antenna business.

Sorry for the novel.
tl;dr I recommend dielectric grease on the gasket and not grounding your radio to the battery or primary grounding strap of the battery.


"need" is a strong word. NMO mounts are designed for the underside to be internal to a vehicle not exposed to the elements. There are enclosed ones (looks like the midland is sort of enclosed) that help with rain, road salts, etc...

There are pretty much two camps of people: the "let it ride" and replace it if need be camp and the weatherproof camp. Personally I'm in the latter; I don't like exposed steel/brass/copper/aluminum especially if it's supposed to be carrying electrical signals (RF included). Circled is some corrosion of the copper threading of this NMO antenna that hasn't seen a lot of use and no dielectric grease.

Your NMO mount should have 2 gaskets on it, one underneath to prevent water from coming into your vehicle from the hole you drilled and one inside the antenna. This is not the same NMO as you have, obviously. The red arrow points to the gasket I put some dielectric on (and apparently so does @Y E T I). Green is also an area I've been known to apply some dielectric and wipe off excess. Dielectric is cheap and useful for packing the outside of all vehicle electrical connectors with as well.

Something I've never done, but have seen others do, is apply epoxy putty or similar to the bottom of the NMO (circled). I'm not sure I would do that, but I do apply marine grade adhesive heatshrink between the cable guide and the cable when I'm building/rebuilding the NMO mount. (You can see copious heatshrink in the above and 2 pictures down is a factory heatshrink of the crimp)

Mounts like this (Larsen NMOHF) are generally considered decent for outdoor/external mounting, but this could be exactly what's in the midland mount and they went a step further and enclosed it in plastic ? Unsure. Midland is known for [offroad] radio solutions, so I have to think they put some thought into that and it should be fine. I was curious which camp you were in.

Also since you said you're new to this whole antenna thing, every antenna works better with a ground plane (metal reflector) beneath it at least as big as 1/4 of the wavelength. I'll save you some math and for GMRS it's just over 6". Bigger antennas, bigger ground planes, and to an extent more power = longer distance. Once again... two camps.

- "If it aint broke dont fix it". Leave your antenna where it is until you find its coverage/distance is insufficient. Aka offroad until something scrapes/breaks then upgrade/add on.
- Can't stop the tinker camp, of constantly looking for improvements, tweaking placement, cable length, phase, a million other things. Aka build a badass machine then go offroading.

Where did you ground your radio ? <- another divisive subject. I don't think we should be grounding radios to the battery or the primary battery chassis ground for 3 reasons:

1. Adaptive charging system our trucks employ
2. Interference/feedback from other electrical systems reducing range/clarity of radio transmissions
3. Failed battery grounding strap could send enough voltage into the radio to set it on fire...

 

[F8LZ71]

Sorry for the novel.
tl;dr I recommend dielectric grease on the gasket and not grounding your radio to the battery or primary grounding strap of the battery.


"need" is a strong word. NMO mounts are designed for the underside to be internal to a vehicle not exposed to the elements. There are enclosed ones (looks like the midland is sort of enclosed) that help with rain, road salts, etc...

There are pretty much two camps of people: the "let it ride" and replace it if need be camp and the weatherproof camp. Personally I'm in the latter; I don't like exposed steel/brass/copper/aluminum especially if it's supposed to be carrying electrical signals (RF included). Circled is some corrosion of the copper threading of this NMO antenna that hasn't seen a lot of use and no dielectric grease.

Your NMO mount should have 2 gaskets on it, one underneath to prevent water from coming into your vehicle from the hole you drilled and one inside the antenna. This is not the same NMO as you have, obviously. The red arrow points to the gasket I put some dielectric on (and apparently so does @Y E T I). Green is also an area I've been known to apply some dielectric and wipe off excess. Dielectric is cheap and useful for packing the outside of all vehicle electrical connectors with as well.

View attachment 410606

Something I've never done, but have seen others do, is apply epoxy putty or similar to the bottom of the NMO (circled). I'm not sure I would do that, but I do apply marine grade adhesive heatshrink between the cable guide and the cable when I'm building/rebuilding the NMO mount. (You can see copious heatshrink in the above and 2 pictures down is a factory heatshrink of the crimp)

View attachment 410607

Mounts like this (Larsen NMOHF) are generally considered decent for outdoor/external mounting, but this could be exactly what's in the midland mount and they went a step further and enclosed it in plastic ? Unsure. Midland is known for [offroad] radio solutions, so I have to think they put some thought into that and it should be fine. I was curious which camp you were in.

View attachment 410608

Also since you said you're new to this whole antenna thing, every antenna works better with a ground plane (metal reflector) beneath it at least as big as 1/4 of the wavelength. I'll save you some math and for GMRS it's just over 6". Bigger antennas, bigger ground planes, and to an extent more power = longer distance. Once again... two camps.

• "If it aint broke dont fix it". Leave your antenna where it is until you find its coverage/distance is insufficient. Aka offroad until something scrapes/breaks then upgrade/add on.
• Can't stop the tinker camp, of constantly looking for improvements, tweaking placement, cable length, phase, a million other things. Aka build a badass machine then go offroading.

Where did you ground your radio ? <- another divisive subject. I don't think we should be grounding radios to the battery or the primary battery chassis ground for 3 reasons:

1. Adaptive charging system our trucks employ
2. Interference/feedback from other electrical systems reducing range/clarity of radio transmissions
3. Failed battery grounding strap could send enough voltage into the radio to set it on fire...

Thanks for the quick study! I'll definitely apply dielectric grease! As for the radio ground, I'm still just using the cigarette lighter adapter for power and ground. That's how the kit came. Do you recommend otherwise?

I have read about the ground plane after I ousted it the way I did. I'm going to pivot the antenna to sit more over the hood now. And if that doesn't work I'll mount to the roof rack. My old little magnetic antenna worked pretty well up there.

 

[ARCowboy]

Thanks for the quick study! I'll definitely apply dielectric grease! As for the radio ground, I'm still just using the cigarette lighter adapter for power and ground. That's how the kit came. Do you recommend otherwise?

I have read about the ground plane after I ousted it the way I did. I'm going to pivot the antenna to sit more over the hood now. And if that doesn't work I'll mount to the roof rack. My old little magnetic antenna worked pretty well up there.

I should have mentioned this in the first post but try not to get too much dielectric on the threads, as NMO mounts use the threads/body for ground. Strange, I know, since the NMO mount pictured above doesn't have bare metal threads... I get continuity with a multimeter on that mount from threads to barrel of connector though, we have hundreds of them and antennas sweep/smith chart just fine on them, so shrug. I'll take this moment to recommend checking for DC ground continuity between your NMO mount and the underhood ground of the vehicle. That ghost antenna shouldn't be a lightning rod but taller antennas definitely can be... and thus should be DC grounded. (It should).

If the 12v accesory outlet is working (good location for you, not annoying, no static from your truck speakers, no strange DIC indications, and no reported noise from others listening when you talk), I'd keep it. That lighter port is cab grounded at G300, "In the passenger compartment, center, beneath the floor console, rear of floor shifter".

 

[F8LZ71]

Thanks so much! You're a wealth of knowledge. I know to hit up when I build up a HAM system.

 

[ARCowboy]

Thanks so much! You're a wealth of knowledge. I know to hit up when I build up a HAM system.

There's a wealth of knowledge on this forum I've appreciated since buying the truck in 2016, so I try and give back where I can. It's a shame you're on the wrong coast (I think) otherwise I'd offer to meetup for a trail or two and to sweep your radio setup

 

[OnyxGMC]

Been reading this build log for 30 minutes now, what a journey this truck has been through. Ton of great information that will and has been VERY useful thank you for sharing! This thread is like an encyclopedia lol

This last weekend I finally got a bunch of parts on eibach 2.0 kit, freedom off road uca's, alpha equipt wheels +20mm, and 275/70/17 wildpeak ATW3's. Along with street rays sway bar relocate + prothane links. Did the waffle trim and pinch weld trim.

Still have rubbing in 2 places: On the freedom offroad UCA's and a bit on the cab-side inner frame/body mount.

I think the inner frame rub could be corrected with the 7mm spacers you utilized in the past, if you haven't sold them I would gladly buy em! Otherwise i'll order some, you got the hub centric to car and hub centric to wheel option with 66.9mm center bore, correct?

Also thinking the width/curve of those freedom UCA's is my issue - they'd be fine with closer to 0 offset or skinnier tires. Going to see if the skinnier stock UCAs rub or maybe just pony up the money for boxed style ucas like dirt kings, they seem to be less round and more triangular which would help.

 

[Oo.et.oO]

and a bit on the cab-side inner frame/body mount.

interesting! i did my trim at front wheel rear last week (1" leveling blocks, 1.5" spacers, 32" tires) and i still rub near that body mount, but it's hitting part of the wheel well liner above the edge. i put a zip tie around that body mount and it helped. not that it would help your situation.

 

[Chaseadeventure]

Hey guys, new here. I noticed you trimmed up your bumper and wanted to find out if you took some pics of what you did. or a video. I am getting ready to throw new wheels and tires on my truck and know that i need to do some trimming so that the tires won't rub. Also saw you are running 33's on it how has that been running when you go off road. do you have any issues with rub when terraining?

 

[Its.exit]

Hey guys, new here. I noticed you trimmed up your bumper and wanted to find out if you took some pics of what you did. or a video. I am getting ready to throw new wheels and tires on my truck and know that i need to do some trimming so that the tires won't rub. Also saw you are running 33's on it how has that been running when you go off road. do you have any issues with rub when terraining?

I was curious about this as well. I just ordered the DV8 half front bumper because of the sale they have right now (down from $550 to $380) and a winch. I also recently placed some KO2s on my truck - 285/60/18 - So far no rubbing, but wondering if that will change with a lift.

 

[Chaseadeventure]

I was curious about this as well. I just ordered the DV8 half front bumper because of the sale they have right now (down from $550 to $380) and a winch. I also recently placed some KO2s on my truck - 285/60/18 - So far no rubbing, but wondering if that will change with a lift.

Hey there, so I ended up cutting my bumper up to stop the rubbing. I am running 285/70/17's did a 3.5" ready lift and no more rubbing, in the front. to make the cuts i used Painters Tape, and String since it's not a flat surface. i still need to go back through and sand it down and finish the inside with some new brackets. but overall super happy with the job. I did notice that I'll need to trim some on the firewall side but shouldn't be much. Tested it last weekend off-road and everything went good. wish I would have been able to take some pictures but when you are a loner you miss out on some shots.

 

[Chaseadeventure]

Hey there, so I ended up cutting my bumper up to stop the rubbing. I am running 285/70/17's did a 3.5" ready lift and no more rubbing, in the front. to make the cuts i used Painters Tape, and String since it's not a flat surface. i still need to go back through and sand it down and finish the inside with some new brackets. but overall super happy with the job. I did notice that I'll need to trim some on the firewall side but shouldn't be much. Tested it last weekend off-road and everything went good. wish I would have been able to take some pictures but when you are a loner you miss out on some shots.

 

[Its.exit]

Hey there, so I ended up cutting my bumper up to stop the rubbing. I am running 285/70/17's did a 3.5" ready lift and no more rubbing, in the front. to make the cuts i used Painters Tape, and String since it's not a flat surface. i still need to go back through and sand it down and finish the inside with some new brackets. but overall super happy with the job. I did notice that I'll need to trim some on the firewall side but shouldn't be much. Tested it last weekend off-road and everything went good. wish I would have been able to take some pictures but when you are a loner you miss out on some shots.

I finally got my tires mounted. 285/60/18 seems to be the sweet spot. No trimming required. I'm pretty sure a lift will only increase my clearance. Regarding a bumper trim, I'm going to wait and see how it looks and functions with the Dv8 once I get it in. Might not be needed.

 

[Chaseadeventure]

I finally got my tires mounted. 285/60/18 seems to be the sweet spot. No trimming required. I'm pretty sure a lift will only increase my clearance. Regarding a bumper trim, I'm going to wait and see how it looks and functions with the Dv8 once I get it in. Might not be needed.

Those look good. post the Bumper once you have it on so I can see.

 

[Its.exit]

Those look good. post the Bumper once you have it on so I can see.

 

[Its.exit]

I'm not a super handy person. Took me forever to install it (about 8 hours). The biggest issue I ran into was removing the center part from the bumper (had to remove grille first, which I didn't know) and getting the grille reattached to the bumper was a nightmare. I finally discovered if I just put the grille on the car first (which isn't how anyone else instructed in any videos Ive seen) and put the bumper on afterwards, it was very easy.

But it looks pretty sweet now and I'm glad I have a winch in case I get stuck when I start camping with my trailer. Plan to do some boon-docking get off the beaten path a bit. Pic of my trailer below.