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Common swr problem..
- Thread starter Splash1
- Start date
I have only noticed it on antennas that have matching devices built into them. Antennas that don't such as a 102' whip or a dipole that doesn't have a balum or traps the SWR should not rise unless you are running some outrageous amount of power.
One time I hooked up a 1500 watt amp and I thought my SWR was higher, but after looking at it closer the reflected power was the same percentage, it just looked higher. For example, if an SWR of 1.3:1 reflected 5 watts out of 100 watts then 75 watts would be reflected out of 1500 watts and is more noticable on the meter.
One time I hooked up a 1500 watt amp and I thought my SWR was higher, but after looking at it closer the reflected power was the same percentage, it just looked higher. For example, if an SWR of 1.3:1 reflected 5 watts out of 100 watts then 75 watts would be reflected out of 1500 watts and is more noticable on the meter.
SWR doesn't change because of the power level, it stays the same no matter what power is used. An SWR reading can certainly change if the SWR meter isn't calibrated for the power level it's being used at, or if whatever that power level is, the meter isn't made to handle it. If that change is a small one, I wouldn't worry about it, it's probably just because the meter is slightly inaccurate. 'Small' meaning the number following the decimal point, and maybe one or two of them. If that change approaches about 25 to 50% of the total reading, then I'd start wondering why.
- 'Doc
- 'Doc
The percentage table you want is here.
SWR and TRANSMITTERS - What is SWR all about? Making Sense of SWR Readings
Another reason for swr worsening with higher power is that amplifiers put out more harmonic power when pushed harder, and antennas always reflect most harmonic energy back to transmitter instead of radiating it. Also swr/power meters can give falsely higher readings at the harmonic frequencies.
Calculating SWR by knowing forward/reverse power reading?
Sure, 'Bird' does it all the time, typically send a chart to do it with their meters. Is that any more accurate than an SWR meter's reading? Not really, just depends on how accurate any of those meter readings are. That SWR meter just does that figuring for you electrically.
There are a lot of things that can affect SWR. Figuring out which one of those things is causing the problem is the job of the operator, unless that operator pays for the convenience of some kind of test equipment to do that thinking for him. Even so, the operator has to know how to work that 'doo-hicky' to know anything about what it's telling him. It just amounts to that operator knowing his "stuff". Then, it just ain't no "stuff", sort of.
All kind's of "but's" in that. The 'trick' is to eliminate them till there's only 'one' left. The hard part is having some idea about which "but" is more likely than another "but", and why. When you get to the point where the only "but" left is the color of the thing, then you'd better go back and check stuff again.
Nothing wrong with striving for perfection as long as you realize that you ain't never gonna get there. Close sure, but never 'perfect'.
- 'Doc
I think that after you ponder the in's and out's of SWR for the next couple of ice ages, you'll find that it's one of the most over rated measurements you can do overall. It's easy though...
Sure, 'Bird' does it all the time, typically send a chart to do it with their meters. Is that any more accurate than an SWR meter's reading? Not really, just depends on how accurate any of those meter readings are. That SWR meter just does that figuring for you electrically.
There are a lot of things that can affect SWR. Figuring out which one of those things is causing the problem is the job of the operator, unless that operator pays for the convenience of some kind of test equipment to do that thinking for him. Even so, the operator has to know how to work that 'doo-hicky' to know anything about what it's telling him. It just amounts to that operator knowing his "stuff". Then, it just ain't no "stuff", sort of.
All kind's of "but's" in that. The 'trick' is to eliminate them till there's only 'one' left. The hard part is having some idea about which "but" is more likely than another "but", and why. When you get to the point where the only "but" left is the color of the thing, then you'd better go back and check stuff again.
Nothing wrong with striving for perfection as long as you realize that you ain't never gonna get there. Close sure, but never 'perfect'.
- 'Doc
I think that after you ponder the in's and out's of SWR for the next couple of ice ages, you'll find that it's one of the most over rated measurements you can do overall. It's easy though...
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