Monday, December 28, 2009

Antenna, round 2

Ham friends:

Ok...trying again. I cobbled up a new way of mounting a comet SBB5 antenna on the roof of my truck. I still have the old plate up there, glued to the roof. ( we cant drill anything).

First photo is the plate that used to be the home for my old magnetic dual band antenna that died. Still hanging in there is the old tape and the old radial wires. Also visible is the factory CB antenna on the other side of the cab, and the XM antenna ( not mine) stuck on with...velcro!

I bolted a rectangular aluminum plate to a large strong magnet mount 'blank'. I attached (4) 19" radial wires to the 4 corners of the plate as a counterpoise and mounted an NMO mount offset on the plate, and then bent the edges of the plate down to help block the spray nozzles in the wash bay we use. Then I thoroughly sealed up the underside of the mount with more of that wonderful sealer, GOOP.

I also used a piece of 1/2" heatshrink, and put it around the lower matching network/coil on the antenna, to guard against the powerful spray jets from getting any water and or cleaner into the coil, with its setscrew holes and weepholes and seams. I squirted in some GOOP at the top, and secured it with a couple of zip-ties. Yes, its all very ugly, but cant be seen by anyone on the ground.

Then I used an extension ladder to get up there, which you can see the shadow of in the pics. I stuck the whole ugly mess to the plate that seems to be still holding tight to the roof. I used white duct tape to fasten the radials to the fiberglass cap. I routed the coax down the cap, along the door jam, and then into the cab. Checking SWR on 2 meters...its 1.1!!!

I will have to check the SWR on 440 later, as I did not have a meter for that band with me when I went to the yard to get this done.

Heading out tomorrow, wish me luck!

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