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Antron 99 Problems
- Thread starter ve3tww
- Start date
Is the base of the 99 grounded tp the tower, and the tower to a good earth ground? If the base of the GP is insulated, the ground return must travel all the way to the other end of the coax, and then, to whatever the closest ground point is, be it the Radio, lighting arrestor, tuner etc... That will electrically make the antenna longer, so the SWR will read lower as you move down from 10m towards 11m.
Was the coax used during testing, the same coax you use in the air? If not, It could be bad. If it was the same you used to test, was it coiled-up on the ground when the antenna was tested on the stinger? That would create a perfect balun, changing the impedance of the whole system.... The best coax can start to go bad in one rainy summer season. The dialectric insulation can absorb moisture, and condensation can collect under the jacket and it takes little more than a nick. The shielding can turn black and begin to change velocity/impedance. If you have 3 feet or so to spare, take the easiest end to work on, cut the connector off and peel-back the jacket. If it is not shiny copper and is tarnished-looking, cut another foot off, and so-on until it's clean. If it was clean the first shot, you might want to check the other end... If you end up with forty 1foot pieces of coax, it was no good anyhow, and now can easily fit in a recycle bin.
I realize it probably wont be easy to check the high end. But those are about everything I can think of that would change the SWR that drastically. And the lack of ground radials shouldn't change the SWR very much, if at all.
Was the coax used during testing, the same coax you use in the air? If not, It could be bad. If it was the same you used to test, was it coiled-up on the ground when the antenna was tested on the stinger? That would create a perfect balun, changing the impedance of the whole system.... The best coax can start to go bad in one rainy summer season. The dialectric insulation can absorb moisture, and condensation can collect under the jacket and it takes little more than a nick. The shielding can turn black and begin to change velocity/impedance. If you have 3 feet or so to spare, take the easiest end to work on, cut the connector off and peel-back the jacket. If it is not shiny copper and is tarnished-looking, cut another foot off, and so-on until it's clean. If it was clean the first shot, you might want to check the other end... If you end up with forty 1foot pieces of coax, it was no good anyhow, and now can easily fit in a recycle bin.
I realize it probably wont be easy to check the high end. But those are about everything I can think of that would change the SWR that drastically. And the lack of ground radials shouldn't change the SWR very much, if at all.
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Have you any way of furnishing more information about the change in the antenna's environment. What you've said really isn't enough to give you any pertinent advice. There are a lot of possible reasons for an SWR change. A difference in the feed line from the short mast to the tower is one of those reasons. Do you by any chance have an antenna analyzer available?
- 'Doc
- 'Doc
I also have an A-99 and my swr is about 1.3.1 on all 40 channels, the problem could be any patch coaxes and or switchboxes, if your using one, I have a switchbox that'll raise my swr to 2.5.1.
Another question is do you have a ground plane kit on your a-99, some people say that don't matter, but it is suppose to help cut down on the swr for a better match as well as deflecting the signal better. I get out pretty good for what little I have.
Some linears can also raise your swr as well. Do you have another radio to test with and are you testing with a fairly good swr meter or the radios built in swr.
I agree that your not giving enough info and there are to many variables to consider.
Another question is do you have a ground plane kit on your a-99, some people say that don't matter, but it is suppose to help cut down on the swr for a better match as well as deflecting the signal better. I get out pretty good for what little I have.
Some linears can also raise your swr as well. Do you have another radio to test with and are you testing with a fairly good swr meter or the radios built in swr.
I agree that your not giving enough info and there are to many variables to consider.
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