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2020 Chevy Silverado install

mmckenna

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I've done a 2018 and a 2020 Chevy half ton Silverado, so figured I'd drop some photos/specs for those that decide to do their own.

NMO permanent mount is fairly easy in these trucks.
With a sun roof or not, you can drill your hole 16 inches from the rear edge of the cab sheet metal. Note there there is a composite 'wing' on the back of the cab. My measurement was from the edge of the sheet metal where it meets the wing. 16 inches will get you in the right place, just behind the dome light, and out of the way of a sun roof if you have one.


Dome light is a bit of a challenge to get out, but it does come out. Easy to run the coaxial cable forward to the dome light and drop the slack into the cab. Once you have it there, you can route it.
A bit blurry, but this is looking back towards the NMO mount from the inside:


Photos are a bit out of order since these were taken in two different trucks about 2 years apart...

The fun part:
Drilling the hole is easy. 16 inches forward of the rear edge of the cab roof sheet metal. Center left/right.


Route your coaxial cable in and forward to the dome light hole:


Seat the NMO mount in the hole:



More to follow….
 

mmckenna

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Put some silicone lube on the O ring under the nut. Some NMO kits come with it, some don't. The silicone grease helps hold the O ring in place when you are installing the nut, and keeps it from binding up and tearing when you tighten the nut down:


Routing the coax will be an individual thing. You need to be aware of the side curtain air bags and NEVER route the coax in a way that would keep the air bag from deploying. Route the coax either forward to a point where you can get down the A pillar, or better yet, route down the back corner of the cab to the RF decks behind the seat. Both trucks I installed in were 4 door cab models, and the RF decks were located under the rear seat. Coax went back to the very rear corner and down.

Power is your other challenge. Fortunately these American trucks are fairly easy. The 2020 I just installed in had the 6 cylinder Duramax Diesel, gas engines may vary a bit. On this one, removing the fuse module off the top of the battery by loosening the battery post clamp with a 10mm socket, releasing the clip on the fender side and pulling it straight up. There's a sensor you will need to unplug, pull the red tab out and release.
Negative terminal is 10mm nut also. Loosen that and move it out of the way. Remove the battery to expose the feed through point:


You'll need to cut the end of the little nipple on the boot. That'll let you pass up to a 6 gauge wire through. Had to apply a bit of grease to get it started. It comes out behind the glove box and it's very crowded back there. I had to use a flexible inspection camera to find it and pull it down. I fed through a piece of 14 gauge solid THHN wire to act as a pull string. The 8 gauge stranded MTW wire was attached to that and pulled through. Once you have it in, you can replace the battery and fuse module:


Power feed was routed down near the passenger side kick panel, and under the door trim to the rear of the cab and the RF decks. The 8 gauge is plenty big enough for one radio and some extra capacity. I fused it for 30 amps at the battery. Ground is picked up from a local bolt under the seat. Manufacturers vary, but GM and Ford are OK with up to 30 amps being run back to the battery via chassis ground.

Fuse was located in the void space between the battery and the fender:


BlueSea Maxi-Fuse mount:


More to follow.
 

mmckenna

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Getting to the battery positive terminal is pretty easy, just through the hole next to the battery and up and around. GM even gives you a nice access path.


5/16 terminal lug will fit over the metric stud.

When it's all buttoned up, just one visible length of split loom:


My ultimate goal is for there to be no visible wiring and for everything to look stock.

This is my brother in laws new truck, so his Kenwood TM-D700 dual band radio. Not quite finished up, but the radio head fit in there like it was made for it. He'll eventually mount it properly, but we'd run out of time.



Larsen NMO-2/70SH mounted on the roof.

He'd been running a full length Larsen NMO-2/70 for years and always been happy with it, however the open coil did give a bit of wind noise. He's happier with this antenna, and I think it looks better.
 
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mmckenna

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For giggles, here are the sweeps for the Larsen NMO-2/70SH antenna:

On the VHF band, 130-174MHz, Nice low SWR in the 2 meter band, but does pretty well outside the band, like I'd expect from a 1/4 wave VHF antenna:


On the UHF band, a bit lumpy, but still pretty good across not only the 70 centimeter band, but most of the UHF band:


And here's looking at everything from 100MHz to 900MHz. Yeah, I know, a dummy load will give you a nice low SWR across the band. I'm simply pointing out where the antenna is resonate:
 
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GRC

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Are you running any accessory powered or straight battery? I’m having the same install in my 2019 but the ignition power is shutting down when the truck stops at idle on red lights.
 

mmckenna

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Are you running any accessory powered or straight battery? I’m having the same install in my 2019 but the ignition power is shutting down when the truck stops at idle on red lights.
It's my brother in laws truck, and he wanted full time power. So all power is straight from the battery.

He was talking about the idle shutdown.
On the Diesel, if he leaves it idling it'll shut itself down after 20 minutes. He often does that when he has to leave his dog in the truck.

As for the shutdown at the stop lights, he's noticed it won't do it if the transmission is in Tow/Haul mode. The truck is only a week old, so not sure if that's the way it's supposed to work or not, but that's what he's seeing.

They do have an ignition switched circuit under the dash, but we're not using that. Theoretically that would stay on when the ignition is on, doesn't matter if the engine is running or not.
 

mmckenna

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Staying true to your signature line!

"Just drill the damn hole."
Damn right. I taught them long ago that it worked much better to do it right the first time. All the trucks in the family have a permanent mount NMO in them. This truck just came home from the dealer last week. He was out of town with it, but I did the install as soon as he could get it down to me. He had me drill the hole.

His last truck had 100K on it and the NMO mount. The dealer, a guy we've known since the 1980's, took the truck no questions asked and gave my brother in law $19,000 on the trade. They do not care about the NMO mounts. Trucks go to a broker, usually sight unseen. NMO mounts, if done right, do not impact resale value, as I'm sure you know.
 

mmckenna

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You could add the fuse to the existing box instead of running that hot wire around it. GM UPFITTER - Body Builder Manuals
Chevrolet Silverado LD (1500) Pick Up ELECTRICAL Section (NEW body style)
starting around p.217 F10 and F11 and connectors X10 and X11, they are designed to be added to by "upfitters"

That's essentially what I did. There were no fuses installed in the slots, and didn't want to try and track them down on a Sunday, so I used the BlueSea Maxi Fuse holder. Those are easy to find at any auto parts store.

If I was doing several of these, that's probably the route I'd take. Would make wiring a bit faster.
 

OhSixTJ

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Does the SH antenna have a spring base?
And yes, the regular 2/70 screams in these newer GM trucks.
 

KK6ZTE

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Are you running any accessory powered or straight battery? I’m having the same install in my 2019 but the ignition power is shutting down when the truck stops at idle on red lights.
Did you read my response to your other thread? There are upfitter connections that can provide key-on power.
 

OhSixTJ

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Yes.
They scream on every truck he's had. This new one, even with the Diesel, is pretty quiet.
do they make a version that does not have a spring? I did some searching and didn’t see one so I’m guessing they do not.
 

mmckenna

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do they make a version that does not have a spring? I did some searching and didn’t see one so I’m guessing they do not.
Back in the 1980's/1990's they made a version with a closed coil. I had one of those at one point, around 1991 or so, and it didn't make a lot of noise. I must have sold it at some point.
Laird still makes a closed coil version, both with a base spring and without.

The NMO-2/70SH came in two versions, also. There was the one with the close coil and one with an open coil. I have/had both. I gave the closed coil version to my brother in law for this install. I have the open coil version at work connected to a scanner. They were 1/4 wave on VHF, so 19 inches or so. The closed coil version has the base spring, the open coil version did not.
 

mrweather

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Well done!

Can't say I've ever noticed "screaming" coming from my open coil NMO-2/70 antenna but then I've only ever mounted it on the trunk lid. Maybe aerodynamics are a little different. I have heard whistling sometimes from my roof-mounted antenna.

I remember the closed-coil NMO-2/70 as well (it's listed in a Larsen antenna catalogue I have from the early 2000's). But I heard it was not as durable as the open-coil version and Larsen discontinued it.

I have the chrome NMO-2/70SH but it hasn't impressed me. I find a plain old 19" antenna to be better.
 

wa8pyr

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They scream on every truck he's had. This new one, even with the Diesel, is pretty quiet.
I've found noisy antenna coils to be an apparent deer deterrent; before I put antennas with coils on the vehicle I had some close encounters, but once the antennas were installed Bambi and his chums generally stay away until I've gone by. I can see them eyeing me warily from the ditch, though. . . .
 

mmckenna

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I've found noisy antenna coils to be an apparent deer deterrent; before I put antennas with coils on the vehicle I had some close encounters, but once the antennas were installed Bambi and his chums generally stay away until I've gone by. I can see them eyeing me warily from the ditch, though. . . .
Yeah, I think you are right.

However, it didn't work out so well for my brother in law on the Trans-Canada highway out in Western Alberta. He hit a buck at nearly 100KPH and did some serious damage to his old truck. Luckily the RCMP was close behind him and offered him a roll of duct tape to hold the front grill/headlight together to make it home.
 

enine

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That's essentially what I did. There were no fuses installed in the slots, and didn't want to try and track them down on a Sunday, so I used the BlueSea Maxi Fuse holder. Those are easy to find at any auto parts store.

If I was doing several of these, that's probably the route I'd take. Would make wiring a bit faster.
They are standard mega fuses, I've found them at Napa. I just doing like that foot or so of unfused wire coming out and going around to the BlueSea holder, I'd be afraid it would get pinched in an crash.
 
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