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crispy coax

T

Trail boss 1

Guest
While salvaging ground wire out of a used cophase coax; I came across a 3ft. section of wire that was different colors than the rest of the shiny copper braid. It alternated in colors from green {indicating corrosion?}, black,and even a rust/coral color it also had a "waxy" feel. No wonder running a single Wilson 2000 is getting out better than the two did. I had adjusted the swr's the way wilson recommended for co phase.



"Dual trucker installation"

Step4.Temporarily connect an 18'length of Rg/58 coax from the swr meter or radio to one antenna.

tune antenna

repeat on other side



two questions

1. what caused the wire to be so corrupted? visually there were no abrasions on the casing. they did pass thru wing vents;that is the extent of pinch.



2. By tuning the way wilson recommends using a different piece of coax to adjust swr's it seems to have maybe masked the problem of corrupted wire . any suggestions?



Galaxy 44/ palomar 225/ wilson 2000




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Sounds to me that the coax was sucking water through capillary action.At highway speeds in the rain, water can get forced in. Even a small pin hole sized crack in the coax can cause the braid to start sucking water and once it starts it acts like a sponge taking on more water and moisture over time.

You might want to consider coax with a clear jacket as that makes inspection of the braid much easier.

Just my opinion on the coax problem.


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flatland; that makes sense.

I was hoping to get some feedback, as that coax wasn't that old. I am now running the clear stuff.

T.B.


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Hello,



This is a very familiar situation here in Oregon. We get a great deal more rain than most parts of the country.

Flatland has it right. This occured due to 'wicking' of the coax. Two things are important inpreventing this. One is to remember that PL259 connectors are not water-proof, and that if using lugs to connect to the antenna you will get some water migration into the coax. The other thing is that the coax most commonly used as an 'upgrade is RG8x or RG8m (so-called mini-8 ) uses an open-cell foam center insulation. This stuff is the worst for wicking water. I have seen water dripping out of the radio-end of the coax, fairly often.

This kind of coax -will- wick water, and it won't dry-out in anything like a reasonable time. You have two ways to prevent this:

one is to seal the antenna ends with 'coax-sealant'

two is to use coax with a solid center insulation (rg59)

The clear stuff you're using is mini-8 and will develop the same prob if you don't use sealant. This stuff is available at r/s and is a sticky tar-like putty you mold around the connection to be sealed. If you use this stuff, your coax will last for

-years- without this sort of problem recurring.



BTW, you have the procedure for tuning dual antennas correct. Both must be mounted while tuning, but each must be tuned individually. Since you can't adjust one correctly ,when connected to the co-phase coax, a single run of standard 50 ohm coax connected to the antenna being tuned is correct.When both antennas are tuned to exactly the same resonant frequency then connect the co-phase coax and do -not- adjust the antennas afterwards. Your swr will be a bit higher than it was with just one connected, and this is normal. In fact, if it isn't a bit higher, the one thing you can be sure of, is that you are -not- getting the little advantage duals give when spaced as close as any legal-width rig will permit. The slightly higer swr ia an indication that it's working. Remember, SWR is -not- an indication of antenna-system effectiveness, in and of itself. It is merely an indication of how close to 50 ohms the antenna system is.



Hope this helps!


73,

Old #7

David



Old_7@cbtricks.com



http://www.cbtricks.com</p>Edited by: <A HREF=http://pub86.ezboard.com/bworldwidecbradioclub.showLocalUserPublicProfile?login=oldno7>Old no7</A> at: 3/8/02 9:29:16 pm
 
Thank you # 7 that was very helpful. I was wondering about that coax sealant. Even directtv recommended me doing it on my satellite. I will do it on my radio. cophase info/50 ohm info also helpful!

Thanks again!


</p>Edited by: <A HREF=http://pub86.ezboard.com/utrailboss1.showPublicProfile?language=EN>Trail boss 1</A> at: 3/7/02 12:21:11 pm
 
Thanks Charger for keeping this up here long enough for me to get some info!


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