SWR questions

[Cadillacman]

Ive got my antenna 70 foot up. My SWRS were a bit below 1.5. And then i burried the coax that was laying on the ground coming from the antenna going to the house. Then they moved a hair above 1.5(sprinkling rain at this time) Then it started to rain pretty hefty and my SWRS went to a hair below a 2. Is this normal? With changing conditions Moisture/wetness. What could have caused this? What causes SWRs to change?

If you need more info to be able to help me, let me know.

[Stoneman]

Sounds like you need a better ground...Do you have it grounded??

[TwentyTwo-Zero]

If your SWR is changing that much simply by moving the coax and a little moisture it sounds like your antenna is not properly tuned (resonant) and your coax is acting as part of the antenna. Readjust your antenna to obtain the lowest possible SWR reading at the antenna. Add a ground if you don't already have one, and check the condition of your coax. If you're using old or poor quality coax you may need to replace it with better quality coax. If you haven't, seal the antenna feed point to prevent moisture from getting into your coax.

[TwentyTwo-Zero]

If your SWR is changing that much simply by moving the coax and a little moisture it sounds like your antenna is not properly tuned (resonant) and your coax is acting as part of the antenna. Readjust your antenna to obtain the lowest possible SWR reading at the antenna. Add a ground if you don't already have one, and check the condition of your coax. If you're using old or poor quality coax you may need to replace it with better quality coax. If you haven't, seal the antenna feed point to prevent moisture from getting into your coax.

[Cadillacman]

Thanks for the advice, My coax is high quaility suff. And the ends are sealed good. But i dont have a ground. Whats the BEST way to ground? I would like to go the best rout for a ground....

Should i cut some of my coax and only use as much as i need and have no slack? How far should i bury the coax? I put it 8-10 inches in the ground. Or should it be buried?

[231]

Thanks for the advice, My coax is high quaility suff. And the ends are sealed good. But i dont have a ground. Whats the BEST way to ground? I would like to go the best rout for a ground....

Should i cut some of my coax and only use as much as i need and have no slack? How far should i bury the coax? I put it 8-10 inches in the ground. Or should it be buried?

Could be grouding, but honestly to me it sounds like moisture in the coax. I had some pretty decent quality RG8U I bought that I put up and ran for a bit. After the first rain I noticed my standing wave went up some. Then we had a heavy rain and it was much higher and I couldn't tune it out (it was on my 40m dipole). So it had nothing to do with grounding. I pulled it down for inspection one day and all my connections looked great...but I replaced everything anyway. All was good again.

Under further inspection I found a very small pin hole/slit in the jacketing. I'd guess that someone cut some plastic wrapping when it was on the spool or something...but when I started coiling it up to take it inside it started dripping. It didn't have alot of water in it, but it was enough to cause a problem. So just because you have good quality feed line doesn't make it immune from problems. Don't rule it out as the culprit. If you go to the trouble of taking your antenna down to re-tune or ground, check it again...VERY closely!

And usually I run #8 or #10 stranded from one of the u-bolts to an 8' ground rod.

[The Toolman]

Some of the aluminum base antennas will raise swr a bit when they are wet also.


Ron
ol'**Censored**

[Circuit Breaker]

What kind of antenna are you talking about?

Personally, I doubt that grounding is an issue and really should have no impact on the antenna anyway.

While water on any antenna will cause variations in SWR, you shouldn't be seeing anything that extreme. It sounds like water is either getting into a connection somewhere or entering your coax.

You said you buried the coax. Did you bury the coax itself, or did you run it through PVC pipe first? If you buried the coax itself, is it rated for direct burial? If not, then moisture can very easily get into it and have an impact on your SWR...and, through time, cause the coax to corrode.

[Foxhunter]

My neighbor who truly has a 1st class station showed me that he found the best way to route the coax to his tower was underground also. But he used direct burial coax, and there is a difference. Not only for coax but for all insulated wires, the material of the jacket is made especially for this purpose.

Another good idea is for just before the coax comes into the house, make a "drip loop" by bending the coax down then back up right at the entry point forming a "U" shaped bend. This will cause water running down the coax to stop at the lowest point there and not seep right in to the coax connector. Water will seep down and get into that connection there-----that's happened to many people.

Many times when you're SWR changes by moving the coax or even running your hand along it, it can be an indicator of common mode currents. This can often show up when your antenna system is not properly grounded and the coax shield itself begins to "radiate" improperly as if it were an actual part of the antenna.

[Cadillacman]

I got it. I found a big gash in the coax. (replaced now) Im about to run the coax threw some PVC and seal both ends with caps and silicone (drilling holes in the end caps). Ill get this all weather proofed. The SWR's are now well below 1.5 Ill be grounding everything too.

Thanks for the tips and info.