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Author Topic: Water coming out of my RG-8/U coax PL-259!!! HOW???  (Read 9135 times)
KC8CXZ
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Posts: 85




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« on: May 26, 2011, 09:48:23 AM »

Is this possible?  I noticed a little puddle of water coming out of my PL-259 plug for the first time ever.  It started a few days ago, then again yesterday.

I have a 15 year old, 50 foot run of RG8-U 13AWG (Tandy wire) feeding a KU4AB 6 meter square on the chimney, and do have a 'loop drip' bend outside where the coax enters my home.  I know that water cannot possibly be entering from the outside of the coax, but is it possible it is somehow inside my coax, and able to bypass the 'loop drip', even travelling upwards into my shack?  Has anyone else ever had this issue?  Thanks for your comments in advance!

73, Jim
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WB2WIK
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« Reply #1 on: May 26, 2011, 10:30:25 AM »

Normally the drip loop should be at the antenna itself, not at the bottom of a run of coax where it enters the house.

By putting the drip loop in the wrong place, water can enter the coax at the top and develop weight + velocity = pressure so by the time it gets to the bottom of a run, it has enough force to run uphill.  Besides, if water made it through the coax to a loop at the bottom, the coax is destroyed, anyway, and would need to be replaced.

It's very common for water to get into coax and run all the way through it, especially when there's no drip loop at the top of the run, and even more especially when a PL-259 connector at the antenna end is facing "up" (towards the sky), just begging for water to get into it, as is the case with some antenna designs and installations.
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AA4PB
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« Reply #2 on: May 26, 2011, 10:31:04 AM »

Water seeks its own level so if water gets inside the coax in sufficient quantity to rise above the drip loop then it will travel around the drip loop. You could have some cracks in the outer covering of the coax along the line somewhere. Given that it is 15 years old and only a 50 foot run, replacing it is probably the most reasonable solution. If its ever had water in it then the loss is likely to be high anyway.
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AA4PB
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« Reply #3 on: May 26, 2011, 10:38:48 AM »

The idea of the drip loop is to keep water from following along the outside of the coax. That's why one should be placed at the house entrance in order to prevent water from following the coax into the house. If water gets inside the coax then its done for anyway. The antenna end of the coax needs a water-tight seal so that water can't get into it. I don't see where a drip loop at the antenna would be of much assistance in keeping water out of the coax unless the end of the coax (where water would have to enter) is pointed down as a result of the loop.

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K2DC
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« Reply #4 on: May 26, 2011, 11:24:24 AM »

Jim,

    There's another red flag in your original post - Tandy Wire.  Coax from Radio Shack is probably among the cheesiest on the planet.  Before you replace it,do a Google search and find someone who sells Belden RG-8 or Times Wire or some other robust feedline.  AES, HRO, The Wireman, almost ANYBODY but the Radio Schmuck.  You should also be able to find it with connectors mounted and weatherproofing installed.  No reflection on your skills, but I've seen some connector installations done by hams in the past that are mediocre at best.  It costs more, but it could be worth it in the long run.

73,

Don, K2DC
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WB6BYU
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« Reply #5 on: May 26, 2011, 11:46:49 AM »

I had the same problem with a 100' length of RG-214 (double shielded), in spite of a drip loop at the antenna.
The braid acts like a wick to get the water into the coax in the first place if the connector isn't sealed well
enough.

Then imagine if you had a hose full of water instead of the coax:  Even a drip loop where the coax enters the
house won't stop the water, except temporarily as the bend fills with water.  Once that happens, the water
flows though it - there is enough pressure from the weight of the water between the drip loop and the top
of the coax to push water though the loop and out the other side.  Running the coax up from the feedpoint
won't entirely prevent it, as the wicking action can draw water uphill, and once it gets over the bend it
can act like a siphon.

Once you get water into the coax, drying it out won't help, even if you really could do so.  The copper
starts corroding, and without good contact between the crossing strands in the braid the loss goes
up significantly.  (Sometimes shaking the coax will improve performance temporarily as the strands
rub against each other and wear off some of the corrosion.)
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W8KQE
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Posts: 245




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« Reply #6 on: May 26, 2011, 12:11:15 PM »

I'm having the same problem with my 50 foot run for 6m.  We've had a LOT of rain and moisture this season!  What is a good coaxial cable to use for 50MHz (50 foot run)?  RG-8, 213, or 9913?  Not sure what I should go with to feed my PAR Omniangle.
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K1CJS
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« Reply #7 on: May 27, 2011, 06:13:43 AM »

I'll agree that the purpose of the drip loop is to stop water running down the OUTSIDE of the coax from getting into the building.  A loop of coax at the antenna serves no useful purpose for diverting water, but it does if it is put there for strain relief--that is to stop the end of the coax from developing a leak where it is supposed to be waterproofed.

If you have water coming out of the coax, REPLACE IT!  Not only are you letting water get into your house, your radio reception will also be impaired, and every time you transmit you run the risk of blowing the finals of your rig.  I'll also agree that Radio Shack coax isn't the best stuff around.  Belden cable seems to be one of the best. Now here's the rub--Belden also supplies Radio Shack with coax!  I tend to think Radio Shack buys Belden's rejected cables.

For the better cable, RG8X does a respectable job, but RG213 is better.  For a fifty foot run, it would make little difference for both 2 or 6 meter frequencies.  Its when you get into the higher frequencies that you NEED lower loss cabling.
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W8VZM
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« Reply #8 on: May 27, 2011, 07:00:44 AM »

When you replace the bad coax you need to think of a couple more points.

Make sure you buy a quality connector. The life expectancies of the cheaper connectors are a lot shorter than you might think. Also make sure you seal the connector after it is connected. Good quality electrical tape (3M), Coaxseal or the like are an absolute requirement. My method is 3M high quality electrical tape and start about 3 inches below the connector. Wrap toward the connector, overlapping the layers 1/4 to 1/3 of the width of the tape (think shingles). Be careful not to stretch the tape too much, this will weaken it. Take the wrap as high as you can at the connection point. I choose this because my antennas don't live long, I like to change them frequently. Stress loop at the top and drip loop at the entrance. Also pay attention to how your cable  gets through the wall. I have seen nicked coax or holes rubbed in it where it makes the entry through brick or aluminum siding.

I tend to pay for top quality and do it right on the antenna end of things. The point here is that you want to do everything you can to make the best connection at the antenna end to eliminate the frustration of antenna issues when you least expect or can afford them. Good Luck!

Ron W8VZM
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W0BTU
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« Reply #9 on: May 28, 2011, 09:49:55 PM »

Once water gets inside the coax like that, your cable is shot. You need to replace it.
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K7KBN
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Posts: 2825




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« Reply #10 on: May 29, 2011, 08:33:13 AM »

How? Gravity.
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73
Pat K7KBN
CWO4 USNR Ret.
NK6Q
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Posts: 202




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« Reply #11 on: May 29, 2011, 01:06:42 PM »

Capillary action
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G6PHH
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Posts: 7




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« Reply #12 on: May 30, 2011, 07:14:29 AM »

Well Jim,you certainly need a new run of coax to replace the wet stuff.And when the top connection is made (in dry conditions) spend some time and carefully wrap the coax and conector with some quality "self amalgamating tape" to fully waterproof the whole connection against water ingress.
PL connectors and a lot of other connectors are NOT water-proof in any way,in their own right.A waterproofing covering has to be applied after it has all been tested and tightened up.
Now it makes no difference weather the connector faces up ,down or sideways,it has to have aftercare applied to it.The wind will blow rain fog and snow into any small opening it can find.
The drip loop as you described,and already explained elsewhere, is to ensure surface water drips off instead of running into the entrance hole into the building.Also when drilling a hole into the building, incline the hole upwards very slightly going in,to also stop water getting in.
Good luck and I hope that you successfully do a good renovation of your coax.
G6PHH Phil.
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KB1GMX
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« Reply #13 on: May 30, 2011, 10:38:46 AM »

once water gets in at the top it will run out the bottom. Capillary action will insure it moves all the way.

Replace the coax, its dead.  Use good coax RG213, 9914 or Buryflex. Waterproof the top very well.

Allison
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W0BTU
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« Reply #14 on: May 30, 2011, 02:30:39 PM »

Fill the UHF connectors with silicone dielectric compound, and tape the assembly. I've never had water get into outdoor UHF connectors by following that procedure.

I have been filling outdoor UHF and F connectors with silicone dielectric compound, and then tightly wrapping the entire connection with electrical tape, for years. As I wrap it, I stretch the tape so that it perfectly conforms to the connector. I've taken such connectors apart many years later, and the silver center pin/socket was just as shiny as when I assembled it; and there was no evidence of water or condensation in there. The only way water could get in is if it wicked along the braid from somewhere else, and once that happens, you're done for no matter what you do (or don't do) to the connector.

Filling the mating surfaces with silicone dielectric compound (including the threads) and then taping it like like that will keep water out almost forever. Extend the tape out past the connector and onto the coax jacket, using several layers. Keep the tape stretched tight as you wrap it. Be careful not to get the silicone dielectric compound on any surface that the tape will be applied to.

Radio Shack used to sell silicone dielectric compound; whether they still do, I can't say. I have also seen it in auto parts stores, sold in tiny squeeze tubes as "Dielectric Tune-Up Grease", made my (IIRC) Permatex. I think that'll work just fine. Most of what I've used was made by Dow Corning (Dow Corning "5" compound). I forget what I have in the shop here now, but it's in a red pressurized dispenser can. Make sure you get the kind that's clear (not white heat transfer grease!), odorless, and never hardens. In other words, DON'T put silicone RTV (Room Temperature Vulcanizing) silicone RUBBER inside your connectors.


I always clean the PL-259 pin so the silver is shiny, and clean the oxide out of the male connectors with some small cotton swabs. (Denatured alcohol works for that.)

And depending on the "feel" as I slide the connectors together, I sometimes carefully bend the 4 pins towards the center (using a small screwdriver) to increase the contact pressure.

I just got tired of bad connections, and opening some UHF connectors and seeing the silver plating discolored. That's why I started filling UHF (and F) connectors with silicone dielectric compound. I've done this at 144 Mhz with 300 watts, and 28 Mhz at 1500 watts. Never had a problem with a UHF connector since.
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