I use only quad shield and flooded here and Im 25 miles from salt water.
Experience has told me the other stuff is good only for indoors unless you
want to replace it every few years as the common mode crud increases from
corrosion and diode joints forming. Ferrite wont help you then. Other parts
of the country likely arent as bad for large temperature swings, lots of
rain and otherwise high humidity as New Hampshire, Maine, etc.
Its sometimes harder to find and not cheap; 1000' reels are the most
economical if you want to split with somebody. OTOH I would never run
anything but hardline on the ground and dont believe everything you read
about direct burial or other plastic jacketed cable for on ground use since
they never address animals chewing on it.
I lost over 1000' of flooded RG-11 in one winter when I first moved here
from chewing. It was no fun running a 750' length of 1/2" CATV hardline over
a few feet of snow but its still like new after 22 years. Runs from
individual Beverages to switch boxes are either RG-6 or 11, quad shield and
flooded. The antennas work fine from the 130KHz area to 30M, I was listening
to loud oldies music on the LF BCB the other night as well as what sounded
like a large cat fight on an Arabic station on 171 KHz (-:
Carl
KM1H
----- Original Message -----
From: "Guy Olinger K2AV" <olinger@bellsouth.net>
To: <jim@audiosystemsgroup.com>; "Herb Schoenbohm" <herbs@vitelcom.net>
Cc: "TopBand" <topband@contesting.com>
Sent: Thursday, June 21, 2012 11:47 AM
Subject: Re: Topband: Chokes for Beverages
> On Thu, Jun 21, 2012 at 10:40 AM, Jim Brown
> <jim@audiosystemsgroup.com>wrote:
>
>> The other element of transfer impedance is the uniformity and
>> density of the shield, often described as shielding effectiveness.
>> Foil/drain shields designed for use at VHF/UHF (i.e., CATV coax) have
>> fairly high resistance at 2 MHz as compared to something with a decent
>> copper braid, so they're not great shields at MF and low HF.
>>
>
> 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.
>
> 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.
>
> The deterioration would be sneaky slow, and unless one had worked out some
> kind of benchmarking for it, one would never know.
>
> I've got flooded "RG6" to my phased loops-on-ground, and the over-the-air
> outdoor TV antenna, and they're hanging in there so far.
>
> 73, Guy.
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
>
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_______________________________________________
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