[TowerTalk] Balun for older Cushcraft 402CD

Paul Christensen w9ac at arrl.net
Fri Jan 19 08:07:15 EST 2018

Unless there's been a recent design change, Balun Designs (BD) doesn't seal in and around the stainless hardware.  The gasketed cover seals are not the issue.  I've experienced water leakage getting in at the stainless hardware.  

My BD chokes are mounted vertically.  In addition to adding silicon RTV at the hardware ingress points, I drilled two small 1/16-inch holes:  one at the bottom to allow for water drainage in the event one of the seals fails, and a second drilled up at an angle from the bottom corner to act as an air weep.  Internally, the weep hole is above the drain hole to ensure there's no back-suction as water drains.  

Paul, W9AC

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Richard Thorne
Sent: Friday, January 19, 2018 7:47 AM
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

On 1/18/2018 10:29 PM, Dave Thompson wrote:
>   I want to replace the 12 turn coax balun and coax on my older Cushcraft 2 el 40.  Has anyone used the balun from the later XM-240?  I don't see a rating on it and might look for a 4 or 5KW balun (1 to 1).  Anyone used another balun successfully on the beam?  If so I am looking for one with wires to hook to the driven element center and has a coax connector on the side that goes to the shack. I also need to know how it is held on the boom.  I plan on using tape to hold the balun on top of the boom.
> Thanks in advance for the help.
> 73 Dave K4JRB
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