Hey, me again
quick question. i recently installed my wilson 2000 on my pickup truck. I had antennas on before and the swr was near perfect. I put on the w2k ill call it, and my swr sky rocketed to 2-2.5:1 the coil is below the top of my cab as of right now though i am looking to get one of those extended shafts. could the reasoning for this high swr no matter how tall or short i adjust the whip be that the coil is inches from my cab and below the top of my cab? if not what could it be, I know my grounding is good.
wilson trucker 2000 swr
Discussion in 'CB Radio Forum' started by Danger07, Dec 28, 2012.
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The electrical length of the antenna includes the shaft from the mount to the coil, the "apparent length" of the coil, and the whip above. The experiment with the string is just to see if removing the cab body's capacitance from the proximity to the coil is to let you see without lengthening the whole antenna if moving the coil farther from the cab will help. The "engineering facts" on the Wilson site are used pretty fast & loose, and there's a lot of stuff there's that's of dubious validity at best (the thing about how to store excess coax is enough to keep better educated users from taking too much of their treatise as fact, for instance).
So, if moving the coil sideways away from the cab is enough to make your match better (you don't drive down the road like that; it's just a test on a parked vehicle) then the idea is to use a longer bottom mast to raise the coil above the cab.
Remember that part about the whole electrical length of the antenna assembly having to stay about the same overall length to stay resonant? If you add nine inches to the mast beneath the coil, then you should expect to have to remove *around* nine inches from the whip above the coil, so that the overall length is approximately the same. It may vary by an inch or two because of the distribution of the inductive and capacitive reactances distributed along the length of the antenna assembly, but a loose rule of thumb will be that the amount added below will be close to the amount removed above.
By the same token, if you shortened the mast below the coil, you should figure on having to lengthen the whip above the coil, but let your antenna measuring equipment tell you by how much; it may not be an inch-for-an-inch trade.
Dunno if that made it clearer; MsJamie really knows her stuff, and her engineering background does a better job of explaining my little RF burns on my fingertips any day of the week
If I had her command of the mathematical art, I'd now be a successful surgeon, teaching neophyte surgical residents how to isolate the inguinal nerve with a piece of umbilical tape before ligating an inflamed appendix.
73Last edited: Dec 28, 2012
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Thanks all! That part always confuses me especially since no matter if you get the 5coil inch or 10you inch mast wilson sends the same size "whip" i call the portion from coil to the top of the antenna the whip not sure if thats correct but works for me ha. So i have a 10" mast as of right now, im getting the 22" mast so in theory i should cut my "whip" by 10"s to be safe, cut another 2 inches if its not enough, correct? I appreciate all the help just want the best running system i can possibly have
By the way handlebar i left you a pm on another topic as well -
....that was funny!
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