[amsat-bb] Re: Cushcraft 416-TB
daivi248 at zahav.net.il
Wed Mar 23 06:50:14 PDT 2011
>From the cable length that you measure it looks like 3/4 Lambda instead of 1/4 Lambda which is too short for convenience working. From the electrical point of view it is the same, assuming low loss coax.
----- Original Message -----
From: Howard Kowall
To: AMSAT BB
Sent: Wednesday, March 23, 2011 3:28 PM
Subject: [amsat-bb] Cushcraft 416-TB
I acquired a Cushcraft 416-Tb antenna,the so called phasing harness was in bad shape,so I am going to make a new one for it.
I could copy the original one,but yes I am making it hard on myself and decide to calculate the proper cable type and length,and to do that I need to know how the antenna actually works.Here is my problem ,the 2 driven elements have a balun to each of the Tmatchs to make the impedance 50 ohms on each driven element.The original phasing harness is 2 piece of 75 ohm aprox 13" that goes to each driven element and the a so239 connector on the other end of the harness is the 50 ohm feedline.I originally thought this was a matching stub,but when I do the calculation for the matching stub,should only be aprox 4" to each driven element.Am I missing something here,how are they able to do this,does anyone know this antenna and how it works.
Thanks to all who read and respond in advance
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