[TowerTalk] Mounting transmission line baluns

[Jim Thomson]

Date: Thu, 06 Oct 2011 10:48:35 -0700
From: Grant Saviers <grants2 at 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