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SWR Help

LckNLoad

Member
Nov 2, 2011
5
0
11
Hello and thank you.
This is my first time on this site. I recently installed the new cobra 29 LE LCD in my truck. Also a new Wilson 3ft stick antenna. The swr was very low. About 1.2
Today I installed a 225 watt linear. The swr is fine until I turn the amp on then the antenna warning comes on and when I check the swr, it's just over two. However, I was able to shoot skip and spoke to a few people down in Texas. I'm in NY and they told me I sound great. Any suggestions or recommendations? Thank you.

113 LockNLoad-Long Island, NY
 

The issue is more than likely that your radios swr bridge sees a 50 ohm load to the antenna and by adding the amplifier this load is upset which is not a real problem for either the radio or amp as it cannot match to suit it's needs.

If there is no issues with the amp there should not be a problem but if you like you can add an external pwr/swr meter which can be calibrated with the amp turned on in line and you would most likely see a better match.

Hope this helps.
 
Thank you for the help. I have an external swr meter. I will give it a try and see what happens. I was just worried I might ruin the radio. Thanks again.

113 LockNLoad
 
Good luck and make sure your external meter has the capability of calibration and start with that calibration mode at it's lowest setting and increase until you get full scale and only then switch back to swr test mode.

Do this test with the amp on during calibration.
 
Any suggestions of brands? :whistle:

Lol Mack.

But he is on to something here too.
Could well be other antenna installation problems that could be making the issue worse when using the amp. I don't have a very high opinion for short antennas; I think they are a waste of time and money. But if that is what you have, you might re-consider where it is mounted and re-evaluate how proper the install job was done.

Short whip antennas are known for having a very narrow bandwidth; they are barely able to work the entire 40 channels w/o the SWR getting into the bad range. Even with the amp off.

With the amp off, what kind of SWR are you seeing on ch 1, 19, and 40? Is the antenna a mag mount; or is it mounted with a solid mount? Where is it mounted? On the roof or the bumper? All these things will have an effect when the amp is turned on.
 
Good morning all. I will be testing the SWR with an external meter today. I'm running a wilson 3ft stick antenna as I said. Its rated for 750 watts. Its mounted on my doge pickup truck with a metal base, bolted right to the truck, located behind the rear passenger seat. It also had a ground wire which I grounded to the truck. The top of the antenna is up above the roof line by about a little over foot. I used to have a wilson whip magnet mount on top of the roof, but it stuck up so high. I didn't want to deal with that anymore so I tried the smaller stick type. So far everyone I speak to says I sound great. Do you really think I need a longer antenna?
 
Good morning all. I will be testing the SWR with an external meter today. I'm running a wilson 3ft stick antenna as I said. Its rated for 750 watts. Its mounted on my doge pickup truck with a metal base, bolted right to the truck, located behind the rear passenger seat. It also had a ground wire which I grounded to the truck. The top of the antenna is up above the roof line by about a little over foot. I used to have a wilson whip magnet mount on top of the roof, but it stuck up so high. I didn't want to deal with that anymore so I tried the smaller stick type. So far everyone I speak to says I sound great. Do you really think I need a longer antenna?

With that type of antenna you may be too close to the cab still.
 
give the wilson mag mount on the roof a try, it only takes a couple minutes to hook it up and see what it does.
 

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