Hi Les. I haven't had any experience with balanced
shielded cable feedlines. I have used regular balanced
twinlead that was not shielded (300 ohm TV line, 450/600
ohm open wire line, etc.)
300-ohm twinlead results were generally good with a Pennant
antenna. See "http://members.aol.com/DXerCapeCod/pennant.pdf";.
What about just using coaxial cable with transformers at
both ends and one or more "coaxial chokes" consisting of
16 turns of RG-174 on an FT-140-75(J) toroid ? See John
Bryant's "Is Your Coaxial Lead-In Actually an Antenna ?"
article at "http://www3.telus.net/7dxr/ircatech/snake.pdf";.
I'd say try several approaches, then let everyone know
which worked the best.
Mark, WA1ION
<<
Subj: Re: Noise isolation transformers
To: <topband@contesting.com>
Date: Mon, 26 Aug 2002 7:24:56 AM Eastern Standard Time
From: Les Rayburn <les@highnoonfilm.com>
To: MarkWA1ION@aol.com
Mark,
Have you ever experimented with using balanced, shielded
cables such as twinax instead of using unbalnced coax with
isolation transformers?
Lots of discussion on the topband reflector recently, about
this being superior for common mode noise reduction. A balun
is needed at the shack end of course, but otherwise no
isolation is required. Plus the stuff is available cheap as
surplus thanks to the large amounts produced for
high speed data connections.
Your advice?
73,
Les Rayburn, N1LF
>>
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