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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Re: Super high SWR

#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.

3’s

Greg
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jessejamesdallas
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Re: Super high SWR

#409837

Post by jessejamesdallas »

Try a different antenna....
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MDYoungblood
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Re: Super high SWR

#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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Greg
"321, West Manchester Township, PA"

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warlock35po
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Re: Super high SWR

#410197

Post by warlock35po »

Hello Jesse,My guess is the S. W. R. meter is getting interference or it is faulty.The S. w. R. you are seeing should do damage to the radio. Regards, 35po Warlock
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