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Re: [TowerTalk] Balun for older Cushcraft 402CD

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Balun for older Cushcraft 402CD
From: Richard Thorne <rthorne@rthorne.net>
Date: Fri, 19 Jan 2018 12:55:52 -0600
List-post: <mailto:towertalk@contesting.com>
Jim

Good points.

It reminded me that my original post was for tribanders.  The 1116 would be a better choice for 40m.

Rich - N5ZC

On 1/19/2018 12:06 PM, Jim Thomson wrote:
Date: Fri, 19 Jan 2018 06:47:25 -0600
From: Richard Thorne <rthorne@rthorne.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Balun for older Cushcraft 402CD

<Dave,

<Go with a a balun designs? ( balundesigns.com ) 1115d with the studs on
<top.? Go from the balun studs to the element halves with a length of
<wire and ring terminals crimped/soldered.

<For mounting the balun to the boom order the BMP1 balun mounting plate.?
<Nice and easy and clean, no tape needed other than attaching the coax to
<the boom.

<I just replaced a F12 balun (cal-av labs I believe) on my C31.? This was
<the 3rd F12 balun to fail.? They short out for some reason.? JK Antennas
<who now builds F12 antennas also uses Balun Design baluns.

<Every one of my antennas now uses a 1115d balun and not a single problem.

<Rich – N5ZC

##  For his 40M  MONOBAND yagi, a better choice would be the
Balun designs  1116D.     >  6300 ohms..... vs the   5200 ohms of
the model 115D.

##  My  big problem with the balun designs CM baluns is.... their graphs
only depict   RS, XS, RP    for  the resonant freq only!    Thats only telling 
folks
a very small part of the story.    Ideally  you want RP to be very high in 
value.   You also want
RS to also be  high in value, like  90-100 % of  RP.  In all cases, you want RS 
to be
higher than XP.   Since they only depict RS, XS, RP  at ONE freq, they are not 
telling you the full story.
Ideally, they should be graphing  RS vs freq,  XS  vs freq,  and RP  vs freq.   
Only then do you have
enough info to evaluate the CM choke.

##  Their model  1115D  resonates at 14.40892 mhz
Their model  1116D  resonates at 4.75734 mhz

Jim   VE7RF

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