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Old 06-24-2014, 07:06 PM   #1
NN5I
Carl, nn5i
 
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Join Date: Sep 2011
Location: Tallahassee, FL
Posts: 1,441
Default Sermon on the Mount

Sermon on the antenna mount, that is. Last Saturday my new screwdriver arrived from KJ7U. So of course I started thinking how to mount it on my motor home.

At length I decided to make a mount that would attach to the horizontal (athwartship) 3" square steel bar that's part of the Class IV hitch receiver. I figured I could use big square U-bolts, so I went shopping.

At a big trailer-hitch place I bought big square galvanized U-bolts, sized to fit over a 3" square tube. Then at Lowe's I bought galvanized nuts and lockwashers. At a metal place I bought a cut-off end, 34.5 inches, of 6" steel structural channel. Back to Lowe's to buy 1/4-20 hardware for grounding connections. All that was yesterday.

This morning I got up early (before noon, even) and sanded and primed the channel so I could handle it without instantly becoming filthy dirty. Then I started drilling all the necessary holes. This was actually quite a lot of work. Here's the mount with all the holes drilled, and final paint.


This end mounts to the hitch. The big holes are for the U-bolts, and the small holes are for braid connections to the coach's chassis. The holes for the U-bolts are at an angle, because I wanted the mount to stick out at an angle.


This end sticks out in the rear of the coach and is where the antenna is attached. The big hole is for the antenna mounting post, and the small holes are for grounding screws.


Here are the U-bolts. They are pretty strong; the thread is 1/2-13, and they require 1/2-inch holes.


For good grounding, it is necessary to remove paint around the holes where the ground connections go. I did this with a carbide burr on both the top and the bottom surfaces of the mount.


The ground straps (braids) are pretty substantial too, about 1" wide and 1/8" thick. One end is attached to the nice new mount, and the other end will be connected to the frame rails of the coach. I haven't done that yet.


The ground connections are made with capscrews and what I have learned are called keps nuts, with attached star washers for good electrical contact.


Here's the mount with all ground studs mounted, ground straps attached, and the antenna mounting post installed.


Here are a couple views of the mount on the coach, with the antenna mounted.



Here's an underside view of the U-bolts holding the antenna mount to the hitch receiver under the coach. You can see the two grounding braids hanging down because I haven't connected them to the coach's frame rails yet.



Still to do: connect the ground-braid straps to the frame rails. Run coax and the control/power wires from the front end of the coach to the back end. The IC-7000 is mounted on the driver's console, so this is a non-trivial task.
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