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[TowerTalk] Matching 75 ohm hardline for 3 bands

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Subject: [TowerTalk] Matching 75 ohm hardline for 3 bands
From: (
Date: Sat, 31 Mar 2001 16:03:24 EST
In a message dated 3/31/01 8:16:20 AM Pacific Standard Time, writes:

<< t 05:11 AM 3/31/01 -0500, Tom Rauch wrote:
 >> Is there a solution for matching 75 ohm hard-line to a triband
 >> antenna?...
 >1.) Pick a length of 75 ohm cable that does not result in the worse 
 >impedance showing up at the 50 ohm cable connection point at the 
 >transmitter end.
 am I right in thinking that the general answer would be to make the 75-ohm
 feedline a multiple of a half-wavelength at the lowest operating frequency,
 and that the worst situation would be if the 75-ohm were an odd number of
 73, Pete N4ZR
 Contesting is!
Yes.  1/4 wave multiples would give 100 ohms and the feedline would be a 1/4 
wave multiple only on one band.   For .66 coax 91' 2" is a 1/2 wave or 
multiple on all bands based on multiples of 3.562 MHz.  Better yet adjust the 
matching device on the antenna (like hair pins or Gamma/T's for 75 ohms for 
1:1 SWR all the way to the shack and massage the inductance in the pi net to 
favor 75 ohms for max output/efficiency of the final.  Or use a tuner in the 
shack which most 50 ohm rigs have.  K7GCO

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