2011 Chevy Silverado Ideas

[Project25_MASTR]

This is my 2013 Sierra currently (I change things a lot). Excuse the mess.

The mounts the microphones are sitting on are Panavise InDash mounts. That dash arrangement can utilize 3 at once.

The antenna is 6 inches back from the rear dome light, feed line for the two-way stuff comes down the driver's side C pillar. The whip pictured is not the current whip and was tied in a knot just to show it could be.

The diplexer splits the feedline sending the low pass side to the Motorola Astro Spectra Plus under the rear seat and the high pass runs along the threshold and under the carpet just in front of the driver's seat anchors where it pops out to go to the Motorola PM400 (temporarily) mounted on the console. Waiting on a triplexer so the diplexer is just hanging out there currently.

The control cable for the AS+ runs down the cable track under the passenger side threshold up to the kick panel, behind the glove box to where it pops out under the dash.

 

[mmckenna]

I wan to eventually put two mounts on the roof.. 1 for scanner, and 1 for CB. But CB will come later after I successfully do the scanner antenna mount first. That's priority

If you are adding a second antenna, plan your placement out now.

Center of the cab roof is the prime real estate. It's the largest ground plane area which gives best performance.

I'd recommend installing an NMO at the rear of the cab just above the center stop light. This will work fine for the scanner as it's less dependent on a perfect ground plane to work well.
The CB antenna will work best in the center of the cab roof.

You can certainly install the center cab roof NMO mount and put your scanner antenna there until you are ready to add the CB antenna. Or, you could install the scanner antenna at the rear, as this is a bit easier to install. By removing the center stop light it's easy to access the underside of the mount.

For the record, I've installed CB antennas on NMO mounts at the rear of the cab before, and they tend to work "well enough".

As for the CB antenna itself, I'd strongly recommend the Larsen NMO-27C. Good solid, professional antenna. If maintained, they'll outlast the vehicle.

 

[davidjacobs2012]

If you are adding a second antenna, plan your placement out now.

Center of the cab roof is the prime real estate. It's the largest ground plane area which gives best performance.

I'd recommend installing an NMO at the rear of the cab just above the center stop light. This will work fine for the scanner as it's less dependent on a perfect ground plane to work well.
The CB antenna will work best in the center of the cab roof.

You can certainly install the center cab roof NMO mount and put your scanner antenna there until you are ready to add the CB antenna. Or, you could install the scanner antenna at the rear, as this is a bit easier to install. By removing the center stop light it's easy to access the underside of the mount.

For the record, I've installed CB antennas on NMO mounts at the rear of the cab before, and they tend to work "well enough".

As for the CB antenna itself, I'd strongly recommend the Larsen NMO-27C. Good solid, professional antenna. If maintained, they'll outlast the vehicle.

Thank you. I do like that idea of putting the scanner antenna closest to the bed and CB antenna in the center. Is it possible to run the coax through the rear pillars and run it under the floor panels by the doors? I just thought about this..

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[mmckenna]

Is it possible to run the coax through the rear pillars and run it under the floor panels by the doors? I just thought about this.

Absolutely, and that's usually the way I do it. It's easier, less airbag stuff in the back to worry about, too.
The trim under the door usually just pulls straight up. There's a path under there, probably with existing wiring. You'll probably also find a path that branches off from there and runs under the seat to where the center console would be.

 

[davidjacobs2012]

Absolutely, and that's usually the way I do it. It's easier, less airbag stuff in the back to worry about, too.
The trim under the door usually just pulls straight up. There's a path under there, probably with existing wiring. You'll probably also find a path that branches off from there and runs under the seat to where the center console would be.

That's great! What kind of hole saw would you recommend getting? I know there's a bunch out there

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[SteveC0625]

Thank you. I do like that idea of putting the scanner antenna closest to the bed and CB antenna in the center. Is it possible to run the coax through the rear pillars and run it under the floor panels by the doors? I just thought about this..

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Yes, in fact it was easier on my truck than the A pillars.

 

[SteveC0625]

That's great! What kind of hole saw would you recommend getting? I know there's a bunch out there

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Most any of the hole saws marketed for 3/4" NMO are just fine.

If it was my project, I'd order the hole saw at the same time and from the same vendor as the mounts. Easier, less shipping charges, and you get everything you need in one shot.

Do not buy at large tooth hole saw at Home Depot or similar. They are measured on the inside, not the outside diameter. You'll end up with a 7/8" hole which is very, very bad. Get a hole saw that is intended for mounting NMO's.

On steel car and truck roofs, many times I use a 3/8" drill and then a 3/4" Greenlea chassis punch. If the roof is thicker, like fiberglass or heavy guage aluminum, I use 3/8" thick surface NMO's. Those holes you can drill with a regular 3/8" bit. I usually start smaller and then increase up to 3/8".

Or you can buy a 3/8" thin surface NMO and drill with a regular 3/8" bit. Saves the cost of the hole saw, but you have to be able to reach the underside of the hole to insert the bottom half of the NMO. If you pull the black rubber door seal off the top of the door opening, you should be able to get above the ceiling panel to do this.

Regardless of how you do it, remember to route the coax so it does not interfere with any airbags. On my truck, there is an airbag running the length of the truck just above the doors. I slipped the coax between the airbag and the roof and then down the rear pillar.

 

[mmckenna]

Or you can buy a 3/8" thin surface NMO and drill with a regular 3/8" bit. Saves the cost of the hole saw, but you have to be able to reach the underside of the hole to insert the bottom half of the NMO. If you pull the black rubber door seal off the top of the door opening, you should be able to get above the ceiling panel to do this.

This can be nearly impossible to do on the newer trucks. I tried. If you can mount above the dome light, you might be able to go that route.

I'd recommend the true 3/4" hole saw designed for doing NMO's. They have the fine tooth blade that makes a nice cut and have a outer ridge that'll act as a depth stop.
Larsen, Laird, Antennex, etc. all sell similar hole saws.
Consider it an investment. You may not use if for a few years after this install, but at some point in the future you'll likely use it again. Once you go to permanent NMO mounts, you won't want to go back to the compromise installs.

 

[madrabbitt]

I agree. Buy the hole saw specific to antennas. Usually it outlasts the cheap hardware saws, the smaller finer teeth cut the sheet metal better and faster, the collar prevents the saw from punching too deep.

I've been getting some "newer design" NMO mounts off ebay. Sealed bottom half with a FME jack, rather then attached coax. This way I can run a good quality cable pre-made with FME on both ends, which i then get a FME adaptor to whatever jack I need on the radio end. Lets me swap out radios if needed, easier to route thru the truck, and less chance of damage or strain on the NMO end.

Motorola NMO Mobile Antenna 3/4" Hole Mount FME for the NMO mount. Im sure other vendors sell them as well.

 

[davidjacobs2012]

So I took the rear lamp off and came across this. Is there any way around it? It's a slanted metal piece. Thanks

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[madrabbitt]

extended cab or crew cab?

On my extended cab, i found the same thing. Sticking an inspection cam in didnt show me any good way into the cab, so I ended up drilling forward of it (right past the roof dimple) which was the perfect location to mount the antenna and get it into the cab. I just ran the cable straight forward and out the dome light hole, then routed it the way i wanted it.

 

[davidjacobs2012]

extended cab or crew cab?

On my extended cab, i found the same thing. Sticking an inspection cam in didnt show me any good way into the cab, so I ended up drilling forward of it (right past the roof dimple) which was the perfect location to mount the antenna and get it into the cab. I just ran the cable straight forward and out the dome light hole, then routed it the way i wanted it.

It's extended cab. I was thinking of mounting the scanner antennas to each side of the third brake light lamp but it seems like it would be too close to where the metal curves and goes straight down by the window. Then I would put the antenna for the CB more towards the center

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[mmckenna]

Remember that ideally you want equal ground plane in all directions around the base of your transmit antenna. That'll give you the best overall performance. Putting the antenna to one side or the rear is going to reduce that. I have done it on a Chevy Colorado extended cab, but it was with 800MHz antennas and they only need about 3 inches of ground plane.
For your CB, I'd want something bigger.

I'm having trouble remembering the 2011 Chevy's I installed on, I thought there was enough of a flat area just above the third brake light to support an antenna.

 

[davidjacobs2012]

Remember that ideally you want equal ground plane in all directions around the base of your transmit antenna. That'll give you the best overall performance. Putting the antenna to one side or the rear is going to reduce that. I have done it on a Chevy Colorado extended cab, but it was with 800MHz antennas and they only need about 3 inches of ground plane.
For your CB, I'd want something bigger.

I'm having trouble remembering the 2011 Chevy's I installed on, I thought there was enough of a flat area just above the third brake light to support an antenna.

There is enough room for just one antenna. And I do understand what you are saying about the ground plane. I'm saying that I'm going to try to put the CB antenna in the dead center of the cab. Both front to back and left to right center (center of a square).

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[madrabbitt]

crew cab and extended cab have a different internal roof structure. Crew cabs, drill it 2 inches from the back edge, cable can follow the brake light wiring and punch thru the grommet.
Extended cabs, got to get ahead of that piece of roof if you want to get it into the cab easier. Routing it to the cable grommet is pretty damn hard unless you drop the ceiling, and you dont want to do that on anything with side airbags.

I'll be leaving work in half an hour. Ill take a picture of where the antennas are.

 

[mmckenna]

Got it.

Good luck on the install. I know it's a pain to do your first one, especially drilling a big hole in a perfectly good truck, but once it's done you'll be happy. I've never had anyone regret doing a permanent antenna install.

For what it's worth, I did a VHF install on my dad's 2016 Silverado late last year. He picked it up at the dealer and drove straight to my house. Had the drill going about 30 minutes after he drove up. Not even sure the ink was dry on all the paper work.

When you go to drill the hole, put a magnet underneath the area where you are drilling. That'll catch most of the metal chips. Old speaker magnets are good for this. Follow up with a good cleaning. I discovered on a white truck that a few little bits of metal shavings look pretty bad after sitting out in the fog all night. Had a few little rust marks. Cleaned up pretty easily, but a bit of a fright at first.

 

[madrabbitt]

Center antenna is pretty much dead center on the roof. Rearmost antenna shows where you need to drill to not hit that sloped sub structure.

 

[davidjacobs2012]

Okay, I'm about to start planning this whole project out. What are some ideas for the placement of the antennas? I'm planning on mounting 3 antennas (CB, 800Mhz, and a TBD one). Obviously I want the CB in the middle. What about the others?

 

[madrabbitt]

Are you considering a third radio/scanner for that third antenna? CB via the dome light, right behind the roof crossbar. Scanner or whatever just aft of the roof dimple centered, similar to where mine was. Third mount forward and centered. If you see the spotlight in my pictures, there used to be an NMO mount there, the spotlight wires come in thru it. I used to have three in a row.

 

[davidjacobs2012]

Are you considering a third radio/scanner for that third antenna? CB via the dome light, right behind the roof crossbar. Scanner or whatever just aft of the roof dimple centered, similar to where mine was. Third mount forward and centered. If you see the spotlight in my pictures, there used to be an NMO mount there, the spotlight wires come in thru it. I used to have three in a row.

Where is the roof cross bar? Just so I can imagine it

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