Date: Thu, 06 Oct 2011 10:48:35 -0700
From: Grant Saviers <grants2@pacbell.net>
Subject: [TowerTalk] Mounting transmission line baluns
What is good practice for mounting the standard transmission line balun
(DXE, Array Solutions, etc. PVC box with toroid balun inside)? Can they
be mounted directly to a metal plate? Is a standoff needed to minimize
coupling if the plate is aluminum? What distance?
Grant KZ1W
## I have 2 of the AS 'line isolators'. These use Teflon RG-393 wound
over 4
type 33 torroids. 7-16 Din connectors are used on both the input and the
output. I use
one of these isolators on the input side of the remote switch box to
supplement the
baluns at each ant feed point. [ 2nd one is mounted to the spg plate in
basement].
The AS unit has the mess of torroids suspended dead center
in the middle of the large nema box. They don't heat, up, it's wx
proof...and on paper, you won't
add stray C to it by mounting it to a metal plate or boom/mast etc.
## I'd check with jay at AS though. seems to me in some applications, the
'plate' the nema box was mounted
to was a non metallic plate. Any such plate though, is only gonna add 1/4"
extra space between the internal
torroid stack and the metal boom, etc. In mine, the torroid stack is
horizontal..and at the top of the box..with
connectors on the E-W side of the box. [Axis of the 4 x cores is horizontal]
## That alone puts the RG-393 windings a mile above the base of the nema
box. That config will put zip for any extra stray C, between the coax cable
windings..and metal boom, etc.
## I had jay at AS take one of his high power baluns..and modify it into a
line isolator. The balanced output side usually
has these huge ceramic stand offs + a compensation cap across the ceramic
stand offs. [ on the inside of the box].
Balanced side was removed..and a 2nd 7-16 Din connector was installed.
## The balanced version that does use stand offs...the stand offs are big
things..and long. HV types, with O rings etc.
later... Jim VE7RF
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