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Author Topic: Broken NMO Mount  (Read 1460 times)
N3TBY
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Posts: 3




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« on: March 05, 2006, 10:48:18 PM »

I recently had the NMO mount ripped out of the roof of my truck. (2003 Dodge RAM Diesel Quad Cab 4x4) I hit a very low tree branch just right. I got the sheet metal more or less flattened out and some duct tape over the current hole. I'd like to fill the hole with another NMO mount.

I cut a new 16ga sheet metal backing plate to put under the roof and through the new mount. The old one is trashed and is too short to sandwich in the new plate.

I'm sure I'm not the first person this has happened to. Does anybody have any suggestions? Is there a heavy duty NMO mount?
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K0BG
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« Reply #1 on: March 06, 2006, 06:29:44 AM »

I don't know what you used for a plate, so I have to fly blind here.

I've never had that happen to me, but I know others who have. If it were mine, I purchase a piece of DYI steel from Ace hardware. Eighteen gauge is thick enough, and a Larsen NMO has enough thickness range to encompass this extra amount. I'd also put a thin coat of body seal between the layers.

Alan, KØBG
www.k0bg.com
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K5LXP
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« Reply #2 on: March 06, 2006, 01:28:59 PM »

It's happened to me, had a whip get caught up in the chain of the garage door opener.  One more reason to stick to quarter waves, HI.

At the two way shop we'd see it on occasion, no telling how it happened.

I believe Larsen sells a thick metal version of NMO mount, you could check HRO as they carry a good selection of Larsen stuff.

Mark K5LXP
Albuquerque, NM
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AB0RE
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« Reply #3 on: March 18, 2006, 07:25:58 AM »

I hope you've got the problem fixed by now.  If not, I know that Antenex and MaxRad also sell thick plate mounts that would accomodate the additional thickness added by the second piece of metal.

Antenex products can be ordered online at www.antenex.com (MSRP plus $10 shipping).

R&L Electronics (www.randl.com) has a great selection of Maxrad products.

73,
Dan / ab0re
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N3TBY
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« Reply #4 on: March 20, 2006, 10:48:16 PM »

I�ve been busy, but I did get it fixed.

I ended up getting two Larsen mounts and it accommodates up to 3/4� think. Larsen part #NMOHFTK. They are very heavy duty compared to the other ones I had.

I put one in the previous hole in the roof and put a plate on the inside. I mounted the other one on the bed rail. Originally the one on the roof was a 5/8 wave. I think that it is too tall to mount on the roof. So it is now on the bed rail. I just put a cap on the roof mount. I�ll use the one on the roof for a 1/4� wave in the future.
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N7HWJ
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« Reply #5 on: August 11, 2006, 06:56:08 PM »

N3TBY -

Sorry to hear about your antenna problems.  I wanted to ask a couple of related questions.  I'm thinking of installing a Yaesu FT-8900 dual bander in my 2004 Dodge Ram 3500 Cummins.  Have you had any engine computer problems or issues with RF getting into the truck electronics?  Knowing what you know now, what kind of roof mount antenna would you recommend?

Bill, N7HWJ
Gig Harbor, WA
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N7HWJ
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« Reply #6 on: August 11, 2006, 07:11:38 PM »

N3TBY -

If you want to e-mail me directly, I'm at n7hwj@comcast.net.

Bill, N7HWJ
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N3TBY
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« Reply #7 on: August 11, 2006, 11:55:34 PM »

No I haven't had any problems with the computer or other electrical systems. I'm not into HF, but I think it is more of an issue in those bands. Somebody else is probably more knowledgeable in that area.

The truck is a 4x4 and has 35" tires on it. Without the antenna it was it only clears parking garages about 4". I hardly ever go in to parking garages, but it seemed that when the antenna was on top I was always going under things that were low clearance. I moved the mount from the roof to the top edge of the bed. It is mounted just behind the rear window on the driver’s side. The reception has been very good here. It is now about 3-4” higher that the roof.

I ordered the heavy duty mount from made by Larsen ham radio outlet the part # was NMO-HF-THK. This mount was the strongest mount I could find. The quality is very good on this mount. I taped off the bed rail with masking tape and marked where I wanted to drill. I used a step bit or “uni-bit” from the hardware store. These bits are kind of expensive, but I think the best way to drill the hole. This type of bit leaves a very clean edge.

Then it is just a matter of running the coax and putting the nut on the back side. I used a little clear silicone on the edge of the hole to keep it the edge of the hole from rusting. The mount had o rings, but I wanted added protection. Putting the nut on the back side is the worst part of the whole job. I have short stubby fingers; a person with long fingers may have better luck.

To get the coax in to the cab I drilled an under sizes hole in the rubber grommet that is used for the barking brake cable. This can be accessed from the plastic trim between the carpet on the floor and the door.

Jeff
N3TBY
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