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Antenna tuning
Seems like a real problem. If your dip in swr is to 2.5 at ch 20 and 3:1 at ch 1 and ch 40, you either have a bad feed line or reflection. Hopefully you are not using the swr meter in your radio as they are rarely accurate. I would use a separate swr meter and use the shortest possible jumper to the antenna. Use your feedline to connect the radio to the meter. If it reads a good swr there, put the meter close to the radio with the jumper and use the feedline to the antenna. If your swr reads bad you have a bad feedline and it needs replaced. If it shows good then your radio should be fine and disregard what ever the meter onthe radio says. If it still shows high swr after all is checked then the antenna need to be retuned. This is really easy when you have understand that the higher the operating frequency = the shorter the antenna. So if the swr is 2.0 on ch 1 and 2.5 on ch 40, you need to shorten the stinger to get the antenna resonant. If the swr is 2.5 on ch 1 and 2.0 on ch 40 you should lengthen the stinger. Most CB antenna are tuned at the factory, however different mounting places on a vehicle can cause a reflection where the antenna has to be drastically retuned to combat the reflection of the mounting location.
For instance, a friend of mine let me borrow his 6 meter (50mhz) mobile hamstick to use for a while. He tuned it for 50.125 mhz with an swr of 1:1. His mounting location on his truck was on the toolbox behind his cab. when I put it on my truck where the mounting location is off the rear right corner above the bedrail, I found that the antennas resonant frequency was at 60 mhz.
I hope this help a little and if you have any other questions send me a PM.
Good Luck
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Linear Mode
