Sorry if this has been gone over. I have read all the threads on this and still have problems and questions.

I recently went to a roof mount antenna set-up instead of the glass mount. Everything is brand new from the Cobra Ultra III radio to the Wilson Silver Load 2' antenna w/ adjustable tip. I used a 2" exhaust clamp to mount it to the stock roof rack on the left rear corner of the X. I used a cold rolled steel plate to make the mount for the clamp and antenna stud.

Like I said, everything is new:
New Wilson Silver Load 2' Antenna w/ Adjustable Tip & Medium Duty Spring
New 20' Coax routed from the rear with no coils in the line
New Antenna Stud
New Cobra Ultra III Radio

Here are some pics of the mount set-up:

http://i699.photobucket.com/albums/vv351/ColoXterra4x4/Various/2010-12-05_10-14-26_557.jpg
http://i699.photobucket.com/albums/vv351/ColoXterra4x4/Various/2010-12-05_10-15-27_467.jpg
http://i699.photobucket.com/albums/vv351/ColoXterra4x4/Various/2010-12-05_10-15-38_97.jpg
http://i699.photobucket.com/albums/vv351/ColoXterra4x4/Various/2010-12-05_10-15-54_356.jpg
http://i699.photobucket.com/albums/vv351/ColoXterra4x4/Various/2010-12-05_10-16-20_286.jpg

After trying everything I know, I can't seem to get the SWR's down to below 1.5. Right now, they are around 2.0, but I would like to see them below 1.5. I did the readings on Channel 1 & 40 as I have researched. When I check them on 19 or 20, they are below 1.1. Also, I can be sitting near the freeway and ask for a radio check and rarely get a response so I am thinking transmission issues like it's not getting out effectively.

I am not sure what else to do short of either getting a longer antenna or going with an NGP set-up.

Any advice or help wold be greatly appreciated.

The roof rack has rubber grommets - and you may not have sufficient continuity to the roof/body.

I hope the 20' coax you said you used is really 18'....as that would also eff you up.


Your meter, or technique, is also in question, as SWR less than 1 is physically impossible....and less than 1.1 on a field installation is simply not possible....laboratory only type performance.

A longer antenna will improve the performance as far as using your watts more effectively, but not change the SWR.

If its a tuning issue (Length of antenna), the relative SWR for the higher vs lower channels would be proportional.

In some pics, there appears to be a ground wire, but, it appears to be going UP towards the top of the antenna? What's going on there?


:D

The roof rack has rubber grommets - and you may not have sufficient continuity to the roof/body.

I hope the 20' coax you said you used is really 18'....as that would also eff you up.

I only bought the 20' coax because that was all that was available. Everything was way shorter or way longer. I did route it thru the X so that there were only slight curves in it and no coiled areas whatsoever.


Your meter, or technique, is also in question, as SWR less than 1 is physically impossible....and less than 1.1 on a field installation is simply not possible....laboratory only type performance.

The meter is a brand new SWR/Power meter I bought yesterday at Radio Shack. It works much better than the 35+ year old one I was originally using. The readings on 1 & 40 were hovering right around 2.0 and on 19 & 20, they were right around 1.1.

A longer antenna will improve the performance as far as using your watts more effectively, but not change the SWR.

Ok, I was wondering if I should get the 4' Wilson w/ the adjustable tip, but, if it won't change the SWR reading, it probably ain't worth changing. Opinions?

If its a tuning issue (Length of antenna), the relative SWR for the higher vs lower channels would be proportional. :D

Please explain further. Are you saying they should read nearly the same?

I only bought the 20' coax because that was all that was available. Everything was way shorter or way longer. I did route it thru the X so that there were only slight curves in it and no coiled areas whatsoever.

20' is not a harmonic of the CB frequency range, and therefore you want 18'...20' will not work


The meter is a brand new SWR/Power meter I bought yesterday at Radio Shack. It works much better than the 35+ year old one I was originally using. The readings on 1 & 40 were hovering right around 2.0 and on 19 & 20, they were right around 1.1.

I am assuming you don't know how to use the meter then, or, its defective...as there is no way in HELL you are under 1.1 SWR, period

Ok, I was wondering if I should get the 4' Wilson w/ the adjustable tip, but, if it won't change the SWR reading, it probably ain't worth changing. Opinions?

Your SWR is not what you think it is, you are focused on the wrong issues

Please explain further. Are you saying they should read nearly the same?

I am saying that the way you tune an antenna, to adjust the SWR, is based in slight changes in antenna length, maybe 1/4" or so....and that the LENGTH of the antenna, within that 1/4" or so, changes whether you have stronger upper, or lower channels....

.....you are off by about 2 FEET, and think the SWR is under 1.1


THIS is indicative of a MAJOR deficiency in probably MANY issues


You also didn't say what the extra wire going up was from?