Water in coax

[SuperLid]

I usually apply silicone dielectric grease when attaching my coax ends, then I liquid electrical tape over those, and so far I have been lucky.

Maybe you have a vacuum pump, a desiccator and some calcium chloride laying around.

Those things only work with air dielectric coax.

 

[The20poundhammer]

What is that white thing you wound your coax around for the choke?

 

[Shadetree Mechanic]

What is that white thing you wound your coax around for the choke?

It is a piece of 4 inch PVC pipe.

 

[The20poundhammer]

Hmmm that looks nice I may put something together like that.

 

[darklife]

I've actually had this happen with a long 80' run of RG8u eons ago where I remember one stormy night seeing water leach out of the braid at the end into the connector.

Like most suggest the cable is probably toast now but I took down the cable from my tower and let it bake in the sun for a summer and somehow after testing wattage going in and back out it seemed to be okay along with SWR into a dummy load at its end.

Even then the inside of the cable is probably corroded some and isn't healthy anymore but I wouldn't just toss it. I've cut into the ends of the cable to make short interconnects and it looked okay. Clearly if the shield turns green it isn't but maybe I got lucky.

Thing is you have to remember the coax braid will act like a wick and suck up water if not properly sealed. Hard lesson I wish was more common knowledge and shared.

 

[The20poundhammer]

Well I knew better and thought I had it sealed. It's about 150 foot of RF213/U. You can bet it will be done right this time.

 

[Rwb]

Replace coax.
Seal it properly this time.
Mike

yes,i use that rubber tape that self vulcanizes. wrap from bottom half inch below pl259. wrap firm avoid wrinkles wrap to top . then use 3 M electrical tape and go over the rubber tape same way. should stay dry after that

 

[The20poundhammer]

Well there is no pl259 to seal. This antenna is direct fed with center conductor to on side and the braid on the ground side. So going to try and fix it right this time.

 

[brandon7861]

What about using molten wax and heating the end so it wicks up the braid a little. Most waxes have similar dielectric constants to what is used as insulation in coax cables, so that should be better than letting water get in there. Liquid electrical tape and things like flex seal do not get into the braids due to the solvent evaporating and immediately pushing on the sealant, but wax could take advantage of capillary action and go right in.

Edit, and if you think you disturbed it by flexing the cable after it hardens, just reheat it once it is fixed in place.

 

[BC Coyote]

This antenna is direct fed with center conductor to on side and the braid on the ground side.

That's a little odd ! Not sure I've ever encountered a beam that wasn't fed with either a gamma match, hairpin or coax stub..... Is this a homebrew antenna ?
The problem with feeding a beam direct without a match is that it tends to skew the directional pattern, sometimes by as much as 15 to 20 degrees.

 

[sp5it]

All my Yagis are direct fed with choke balun. No issues with direction skew observed.
Mike

 

[BC Coyote]

Yes, choke balun works great, but I didn't see any mention of one. Maybe he does use a choke balun.

 

[Ranch55]

If water gets into the coax at the antenna, nothing will stop the intrusion all the way thru eventually........
The shield braid will act as a wick.......
And corrosion will be the result...... I have seen that happen numerous times.....
A drip loop will not stop the wicking effect......

 

[BC Coyote]

A drip loop will not stop the wicking effect......

It will, but you need to have at least half the loop ABOVE the level of the connector at the end of the coax. If all or most of it is below the connector the water will indeed wick around the loop.
This is a great example of the way it's "supposed" to look being incorrect. We all have this visual of the drip loop neatly tucked below the connector, but it's totally useless there. It looks "weird" to have part of the loop up so high but it is the correct way to do it !

 

[Rwb]

Well there is no pl259 to seal. This antenna is direct fed with center conductor to on side and the braid on the ground side. So going to try and fix it right this time.

interesting. if thats the case make coax go above and open end be on bottom of loop.no matter how much you seal coax,if braid is exposed water follows braid inside