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My swr changed for no apparent reason.

Steve H

Member
Oct 31, 2010
35
0
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I have a Wilson 500 cb antenna on my car and a Cobra 29 ltd radio. I had it adjusted perfectly. It dipped to almost zero movement on channel 20, and on 1 and 40 it was about 1.3. I was so proud of myself for adjusting this thing perfectly. Now I get about a 1.5 on channel 40, and it dips to a low of about 1.2 on channel 10. I know that these are good readings, but I was just wondering what could have happened? I'm guessing that the antenna shifted in it's base a hair, but I was wondering if anyone else experienced the same thing with any kind of antenna before.
 

Hello;Ah the eternal search for the mythical perfect match,oh to be young again,but seriously folks if you get an vswr of less than 2 two1 leave it alone it won't hurt your radio and no one will see a difference on there meter.You are free to disagree but it's true. Regards warlock35po
 
I appreciate the advice, Warlock. Especially the part about "leave it alone". I've stripped threads on antenna screws, just trying to get the swr perfect. So per your advice, I'll let this one ride.
 
your swr is still perfectly acceptable like warlock said . your swr reading can fluctuate when ever you move the vehicle because of differing distances from nearby things that can cause reflection of the signal .
 
The two posts above are correct in that the current SWR is not a big deal however you have already stated that it was better and something has changed and it's not a bad idea to find out why it changed. What you have now may just be a sign or more changes to come.I would look the antenna all over looking for any corrosion (salt used on roads in your area?) especially where the set screw is. Take the whip out after carefully marking how far it went into the ferrule, and clean the end. Check out the coax cable for any cuts in the sheath or kinks or indentations.You didn't say where the antenna was mounted but I have seen trunk mounts affected by a poor connection through the trunk hinges. I had an HF antenna that would go bonkers at times. I traced the problem to corroded/poor electrical connections through the hinges. I bridged the hinges with flexible copper braid and the problem never returned. Just a few things to look for.
 
you say the swr changed. did you do ANYTHING different? in your first test
did you use an external meter?and use the same one in your second reading?
jumpers use the same one both times?
location were u parked at the exact same spot.this can make swr change
depending on whats around you and the terrain.now if ya done both
tests EXACTLY the same and still read different than idk .
 
I have a Wilson 500 cb antenna on my car and a Cobra 29 ltd radio. I had it adjusted perfectly. It dipped to almost zero movement on channel 20, and on 1 and 40 it was about 1.3. I was so proud of myself for adjusting this thing perfectly. Now I get about a 1.5 on channel 40, and it dips to a low of about 1.2 on channel 10. I know that these are good readings, but I was just wondering what could have happened? I'm guessing that the antenna shifted in it's base a hair, but I was wondering if anyone else experienced the same thing with any kind of antenna before.

Is it a magnet mount? if so there maybe condensation between antenna and vehicle body.
 
I appreciate the responses...especially from Captain Kilowatt and HotRod. I am using the built-in swr meter on the Cobra 29 ltd to test the swr, and it has always worked well. For 15 years, actually.

Hotrod suggested an external meter. I don't have a good quality external meter at my disposal, but if you could point me toward one then I would gladly buy it.

Steve
 
vanco swr meter
customcbradios.com
sparkys cb.com
both are good online places only two id do business with
the meter listed works good and not much money.you can
use the external meter but should only be considered a
ballpark figure
 
Is it a magnet mount? if so there maybe condensation between antenna and vehicle body.

You are correct, MrSuburban. I pulled the antenna off of the roof of the car, and wiped away all the trapped water from the antenna base and the car. And the swr went right back to where it was originally. A sincere thanks for the information. And thanks to everyone else for the suggestions. ------Steve
 
You are correct, MrSuburban. I pulled the antenna off of the roof of the car, and wiped away all the trapped water from the antenna base and the car. And the swr went right back to where it was originally. A sincere thanks for the information. And thanks to everyone else for the suggestions. ------Steve

Well knowing the type of weather we have been having and you mentioning the Wilson it was the first thing i would think of it isn't like your swr went to hell and a handbasket it changed slightly so nothing drastic could have happened. clean under there every so often Glad i could help.
 
Is it a magnet mount? if so there maybe condensation between antenna and vehicle body.

You are correct, MrSuburban. I pulled the antenna off of the roof of the car, and wiped away all the trapped water from the antenna base and the car. And the swr went right back to where it was originally. A sincere thanks for the information. And thanks to everyone else for the suggestions. ------Steve

i pm'ed mr s that answer so he could appear to be smarter than the average cb punk :LOL::LOL::love:
 

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