SWR Question

[radioman148]

I have a cushcraft A3 tribander with a 40 meter add on kit up 60ft on a tower.
On my 2 favorite ham bands 40 & 20 meters my SWR runs 3 or 4 to 1.
I'd like to get it down without my tuner, but I don't climb towers. Am I losing enough signal to worry about it at these levels? The antenna has been up there 25 years.
I have no problems working DX when the band is open and seem to get through to most areas well.
Is it worth the work to try to get it down to below 2 to 1 for me?

Any opinions would be appreciated.

 

[TheStoker]

Hi Radioman.....how long has it been that way? Did it just go up lately?? Don't you see lots of 'foldback' with the rig? 3:1 isn't very good. I'd want 2 or lower. I'm curious what might have happened, water, connector issue??

 

[K6JHU]

Definetly needs to be worked on before it gets worse. You may be getting close to the limit of what an antenna tuner can do for you. That is the key issue. See the section on "practical implications of SWR" in http://en.wikipedia.org/wiki/Standing_wave_ratio

So while you can still operate, a change in SWR (especially if it is short term) is indicative of an issue that needs to be worked.

 

[radioman148]

Definetly needs to be worked on before it gets worse. You may be getting close to the limit of what an antenna tuner can do for you. That is the key issue. See the section on "practical implications of SWR" in http://en.wikipedia.org/wiki/Standing_wave_ratio

So while you can still operate, a change in SWR (especially if it is short term) is indicative of an issue that needs to be worked.

The SWR only goes up when it rains or is wet outside. Otherwise it's under 2 to 1. When I use the built in radio antenna tuner it's always 1 to 1 no matter what. Also 1 to 1 if I use external antenna tuner which of course I need if I run the linear.

 

[KeithE4]

Definetly needs to be worked on before it gets worse. You may be getting close to the limit of what an antenna tuner can do for you. That is the key issue. See the section on "practical implications of SWR" in http://en.wikipedia.org/wiki/Standing_wave_ratio

So while you can still operate, a change in SWR (especially if it is short term) is indicative of an issue that needs to be worked.

The SWR only goes up when it rains or is wet outside. Otherwise it's under 2 to 1. When I use the built in radio antenna tuner it's always 1 to 1 no matter what. Also 1 to 1 if I use external antenna tuner which of course I need if I run the linear.

If the SWR is going up in bad weather, you probably have a loose connection somewhere, or maybe the coax is getting water inside. Either way, somebody is probably going to have to climb your tower.

Using the tuner only keeps your rig happy. It doesn't compensate for a bad antenna (which yours can be considered until it's repaired), especially if the antenna is coax-fed. Losses in coax get much worse with a high SWR, and more of your transmitter's output is being eaten up in the tuner and/or coax.

 

[radioman148]

Definetly needs to be worked on before it gets worse. You may be getting close to the limit of what an antenna tuner can do for you. That is the key issue. See the section on "practical implications of SWR" in http://en.wikipedia.org/wiki/Standing_wave_ratio

So while you can still operate, a change in SWR (especially if it is short term) is indicative of an issue that needs to be worked.

The SWR only goes up when it rains or is wet outside. Otherwise it's under 2 to 1. When I use the built in radio antenna tuner it's always 1 to 1 no matter what. Also 1 to 1 if I use external antenna tuner which of course I need if I run the linear.

If the SWR is going up in bad weather, you probably have a loose connection somewhere, or maybe the coax is getting water inside. Either way, somebody is probably going to have to climb your tower.

Using the tuner only keeps your rig happy. It doesn't compensate for a bad antenna (which yours can be considered until it's repaired), especially if the antenna is coax-fed. Losses in coax get much worse with a high SWR, and more of your transmitter's output is being eaten up in the tuner and/or coax.

Thanks. I'll have to look into it.

 

[marshallstax]

I had the same experience... high swr in bad wx ... but my Windom antenna is put up mainly on weekends, in fair weather, and I think when it got wet one drizzly morning, there was a partial ground path through the wet cord holding the antenna tight and the now-wet wooden poles holding the ends up - one of which was very close to actual ground. Had to have an effect. I don't have proper insulators at the ends of the antenna so the whole affair was essentially grounded when it got wet.

 

[darklife]

I have had SWR go up to 2 and sometimes 3 over 1 in bad weather also while using a J-Pole antenna.
My coax is sealed really well and everything weather proofed. What it comes down to for me is
the antenna itself. There are insulators between the main element and the matching stub.
When the insulators get soaked or ice forms on them it causes the antenna to go slightly out of
tune, usually lowers it's ideal operating frequency by a few MHz.
Lots of other people have similar problems with antennas like that. It doesn't necessarily have to
be your coax or water leaking into parts, though that is a common cause.
There are so many factors that could cause it but this is a common problem for some antenna
designs and setups. If each leg of the dipole part of your antenna is close to each other near
the hanging base then just getting a ball of ice forming around both legs could cause high SWR.
Rain could possibly do the same.

Running a transmitter with an SWR that high is not a good idea. Most transmitters can handle
it but they will run hot. I have seen high powered transmitters blow their outputs at SWRs as
high as 3. It depends on what it can handle.
I find an SWR of 3:1 will get my signal out less than half of what it would with 1.5:1.
So you are probably loosing more than half of the range you would get with the SWR where it
should be!