[TowerTalk] Balun for older Cushcraft 402CD

Jim Thomson jim.thom at telus.net
Fri Jan 19 13:06:58 EST 2018

Date: Fri, 19 Jan 2018 06:47:25 -0600
From: Richard Thorne <rthorne at rthorne.net>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Balun for older Cushcraft 402CD


<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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