If you used plumbing elbows for the turns in your conduit run, it may
be difficult or impossible to pull Heliax through, depending on the number
of turns/elbows. The Andrew spec sheet for LDF4-50A Heliax (assuming this
is the Heliax you're using) shows a minimum bend radius of five inches
http://www.andrew.com/catalog38/Cat38Viewer.aspx?PageNum=496 . I believe
four inch PVC elbows might not give you the requisite bend radius. The
Heliax won't bend enough to follow the inside radius of the elbow without
getting hung up or kinked.
If you used sweeps instead of elbows, the Heliax ought to go through
with less difficulty. If you really need the lower loss of Heliax and you
haven't already bought the stuff, you might want to look into Andrew
FSJ4-50B. This half-inch stuff has a more flexible core and a minimum
bending radius of 1.25 inches
http://www.andrew.com/catalog38/Cat38Viewer.aspx?PageNum=485 . It will
bend more easily for those elbows. But it's even more costly than regular
My advice to you (and that's why you wrote the first query, right?) is
do the math for the max loss you require for your installation and decide
whether you have to use Heliax, or whether -400 would be adequate. (The
fittings and connectors for Heliax are also pricey!) Unless you're using
the coax to feed a 440 MHz or greater weak-signal station, LMR-400 should be
adequate. But do the math.
Gene Smar AD3F
P.S. Yeah, I know - Heliax is a trademark of Andrew Corporation. Sheesh!
P.P.S. Merry Christmas to all.
----- Original Message -----
From: "C. Dwight Baker" <firstname.lastname@example.org>
Sent: Saturday, December 25, 2004 12:36 PM
Subject: [TowerTalk] Heliax and PVC
Good Morning and Merry Christmas to all the brave souls defying their XYLs
to answer this request.
I have installed 105 feet of 4 inch PVC from my shack to the tower. My
question has to do with running Andrews ½ inch Heliax through the conduit.
How flexible or inflexible is the Heliax? I have no experience in Heliax
and trying to make a decision whether to use it or LMR-400.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list