[HCARC] Baluns, Ununs, Gamma Match, Stubs

[Bill Tynan]

Kerry:

Yes but, at the hight most hams erect 1/2 dipoles is so low that the 
impedance is closer to 50 Ohms.

73,

Bill, W3XO
----- Original Message ----- 
From: "Kerry Sandstrom" <kerryk5ks at hughes.net>
To: "Bill Tynan" <billandmattie at windstream.net>; "Gary and Arlene Johnson" 
<qltfnish at omniglobal.net>
Cc: <hcarc at mailman.qth.net>
Sent: Monday, December 10, 2012 6:57 PM
Subject: Re: [HCARC] Baluns, Ununs, Gamma Match, Stubs


> Bill,
>
> That is an interesting approach.  The way I look at it,  the impedance of 
> half a dipole is half of 73 Ohm or about 36 Ohm (same as a quarter wave 
> vertical over ground).  If you use a quarter wave of 75 Ohm coax in each 
> side of the feed, the impedance at the output of the quarter wave sections 
> will be 144 Ohm.  The half wave phasing section in one side will just 
> repeat the impedance so it will be 144 Ohm on each side of the 
> T-connector.  The T-connector is parallel, so the impedance where you 
> connect the coax transmission line to the shack will be 73 Ohm again. 
> Sounds too good to be true!
>
> I'll have to think about how a normal 4:1 balun works with just the half 
> wave section of coax.  That is what I used to use on my 16-element 
> colinear. It seemed to work OK because I didn't melt the coax feed line 
> with my 300 w or so of 2-meter output so it must have been a reasonable 
> match!
>
> Kerry
>
>
>