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[TowerTalk] Phase Relation of Different Cables

Subject: [TowerTalk] Phase Relation of Different Cables
From: Mike <>
Date: Thu, 15 Mar 2007 11:22:06 -0400
List-post: <>

Questions: what is a method for determining the phase relation of a 
pair of cables?  How to adjust the cables to have the same 
phase?  The cables are  made of two different kinds of coax, FSJ-4 
and RG 213.  The cables are different length.  One of the cable 
combinations is more than a wave length at 7 MHz.  The reason for the 
question is the desire to move all the antenna switching mechanisms 
off of the tower to the base.

The ant. system is a pair of F12 EF240Xs, one at 145 feet and the 
other at 70 feet; pair of 4 element SteppIRs, one at 132 feet and the 
other at 100 feet; 80 meter inv. vee with apex at 120 ft at the end 
of a three foot standoff from the tower.  The EF240Xs and SteppIRs 
are controlled by homemade stack matching devices (using 2 to 1 
ununs).  Band selection of the antennas, EF240Xs, SteppIRs and 80 m 
inv. v,  is made using homemade ant. selectors.  Also, the ant. 
system can be split for SO2R using a homemade A:B switch.  All the 
switches and stack matching devices are mounted on the tower from ~ 
80 foot to 110 foot level.  Desire is to remove all the switches and 
stack matching devices from the tower and put in a single box at the 
base of the tower reducing the need climb the tower to repair/replace 
(although hasn't been required in the two years they have been in 
place) any of these devices.  Figure coax is more reliable than relays, etc.

Presently there are two runs of FSJ-4 on the tower, radio 1 and radio 
2, and would like to keep them but they are different length.  Want 
to use LMR-400 for the additional runs to the ant. from the base of 
the tower.  RG213 will be used for rotation loops where required.

Thus the reason for the above question.

         Mike, K4GMH 

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