Well, even Times Microwave who make a stranded (center
conductor and shield) competitior to Heliax(r) admit that
they have somewhat worse IM characteristics. Case closed?
Does anybody really care when it's better than -150 dBc with
the possible exception of some cellular and PCS types?
Please make sure you put the (r) behind the Andrews cable
names as they are registered. Wouldn't want their lawyer
pursuing you, now would we? :)
Happy Holidays and Bah Humbug (Politicially Correct, covering all permutations)
73, Bob AA0CY
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From: Jim Pratt[SMTP:n6ig@netcom.com]
Sent: Tuesday, December 23, 1997 4:52 AM
To: L. B. Cebik
Cc: Pete Smith; towertalk@contesting.com
Subject: [TowerTalk] Stranded vs solid wire
Perhaps slightly off topic, but hopefully interesting nevertheless:
Andrew, the maker of Heliax and Superflex transmission lines, has a
series of "technical documents" that claim to demonstrate the
superiority of solid center conductor transmission line versus
stranded. This also "demonstrates" the superiority of solid shields
versus braided shields. Their dissertations are based on the "facts"
that stranded and/or braided cables have many, many more wire-to-wire
junctions in which intermodulation could be created IF such a junction
were to corrode. If you used a solid shield or center conductor, such
junctions would be eliminated. They have all sorts of laboratory data to
emphasize that.
I still prefer braided cables for pigtails when outdoors, due to
empirical evidence I have about the solid shields breaking in the wind
after years of flexing. Also, it isn't a good idea to use a solid
conductor to go around a rotator joint in an amateur installation as it
will stress and break before a stranded conductor (IMHO).
I am sure it is only a coincidence that Heliax and Superflex both have
solid shields, and that Heliax has a solid center conductor! ;=>
73 and Happy Holidaze,
Jim N6IG
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