Monday, January 4, 2010

Gantry wash

This is our gantry wash...it gets the truck clean but it's rough on antennas...click the play button to view. Please feel free to leave a comment..click on COMMENT, below this video.

video

For more information on these gantry systems, click on this link: Truck Gantry Wash

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!










Tuesday, December 22, 2009

Gantry, 1....Antenna, 0



Greetings...

As some of you know, I've been having some troubles being heard, hitting repeaters...now i know why...when I mounted this antenna on a piece of metal on the roof of my truck cab, I also sealed it with Goop...which is made for sealing...


To keep our fleet looking good, our company uses an expensive gantry wash system, which is mounted on rails and moves forward and backward spraying the tractor and trailer with dozens of highpressure nozzles. There are also some rotating brushes that scrub the side of the trailers. This is similar to an automatic car wash, but much more powerful.


Well the gantry wash and the sunlight UV de-gooped it...and the highpressure nozzles injected some harsh cleaning fluids and mild acid into the antenna base...I'm not sure about the coil yet.
When I finally got around to checking the SWR, it was WAY too high.


This is what 8 months of weekly gantry washes did to my antenna....when I sliced the foil open it dribbled some yucky rusty water out of the inside...and you can just make out the little blue capacitor soldered between the terminals.

Well now I have to figure out how to mount an antenna on a truck with no visor over the windshield, no upper mirror arms, and a fiberglass cap for the cab.