Topband: Chokes for Beverages

[Tom W8JI]

> I have recently replaced some "RG-6" in use for maybe seven or eight 
> years.
> I opened it up to see what was happening.   The degree of oxidation on the
> inside and outside of the foil was perplexing.  One could easily draw a
> thumbnail along either side and build up a little pile of oxide.  The foil
> itself had become very brittle.  It had been "sealed" and treated outside.

Use flooded cable outside.

> If Jim says the shielding needs help when it's new, there's not much hope
> for some varieties when it gets old.  Another reason not to use anything
> other than the flooded variety.  Particularly so for someone who can look
> at the ocean.  I'm hundreds of miles from salt air.  Would need to go with
> flooded for sure close to the ocean.

CATV F-6 or F59 cables are great for 160, or any HF band use. I use ten's of 
thousands of feet of the stuff, much of which has been installed in the 
early 2000's.

My trunk cables are primarily flooded hardline, stepping down to F-11 style 
(F does NOT mean flooded, it is for F connectors) flooded cables for 
distribution, although some F-11 runs are thousands of feet. The longest run 
of F11 is about 3000 feet, and it is dead quiet when terminated.

I have measurements on my webpage of F11 excited by overhead dipoles, and I 
can say with 100% certainty any claims of meaningful shield leakage are 
simply not factual.

The same is true of smaller F6 cables.

The only potential worriesome issues I have seen are lightning melting 
shields. This happens when ground loops create large strike currents in the 
shields. For example, when my towers get a hard whack from a superbolt, the 
common mode current can follow trunks out to my vertical array. That array 
has eight 150-foot buried radials on each of eight elements, and currents 
that massive wide-area ground will occasionally melt a shield on F-6 cables.

Other than that, Racoons, and mowers, F6 through F11 has been flawless. This 
is true in working systems and in actual measurements.

73 Tom