Super high SWR

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Rammrod88
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Super high SWR

#409811

Post by Rammrod88 »

Hey everyone, new to the forum here. I’ve never had an issue like this before

I have a Cobra 29lx with an old midland coffin mic wired up. I have a 200wamp mounted under the passenger seat. I’m using a Wilson trucker 2000 antenna

with a solid mount 8” rise to the coil on my headache rack on my flatbed truck(yes I know roof mount is better but my last one was on my bed rail). Antenna is properly grounded, bed is grounded. Everything worked fine in my last truck when I had it set up with a swr of 1.1-1.2 on 27.175mhz. I have rg8 coax about 15’ antenna to amp and about 4’ amp to radio and when I check with my swr meter at radio plug I get swr=13, not 1.3 but 13. I put the meter on the wire going to the antenna and I got 168. Using MFJ

swr analyzer. I have no shorts in the coax, everything is soldered properly. Do I need the full 18-19’ from antenna to amp? I might be able to shorten up the wire going from radio to amp by re routing it but that requires me to pull my front seat and center console.







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MDYoungblood
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#409832

Post by MDYoungblood »

Mounting the antenna on a headache rack sounds easy but it does cause the problem your having. The problem is the mount is usually several inches above the roofline causing a lack of counterpoise. You can check this by stringing a coupe pieces of wire (8 to 9 ft long) from the mount to the back of the bed, what the SWR go down. This isn’t a fix but gives you an idea. Longer coax in this case could help with a counterpoise too but it isn’t very efficient. I have seen a few members that added a couple short FireStik antennas under mount to act as a counterpoise and said that worked but I’ve never tried it.

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jessejamesdallas
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#409837

Post by jessejamesdallas »

Try a different antenna....






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#409847

Post by MDYoungblood »

jessejamesdallas wrote: January 10th, 2023, 6:17 pm Try a different antenna....
Could probably get a longer stinger (whip) and start over from scratch, I was getting him to understand how the ground plane (counterpoise) works.

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