[TowerTalk] Recommendations for Purchasing a short 2 Element 40 Meter

[James C. Hall, MD]

Is it a coil or coax ? Yes and yes ! :) I use lightweight 3 1/2" sewer PVC and use it as a form for wrapping the appropriate number (depending on frequency) turns of coax (I had Buryflex on hand). You have to drill a few holes in the PVC and use zip (cable) ties to hold the coax while wrapping. Then tape it up nice with Scotch 33 or 88 and put PL259 connectors on each end. I use a Budwig (center dipole connector) and solder ring lugs on the wire terminals and bend them forward for your yagi connection. The SO259 connector of the Budwig makes it easy to connect to and waterproof. Of course you can just break out the two conductors of the coax and put lugs on directly, I just found its more contained to add connectors.

As to the proper number of turns of coax - http://www.k1ttt.net/technote/airbalun.html . Interesting reading.

73, Jamie
WB4YDL

Sent from my iPad

> On Aug 1, 2014, at 12:59 PM, "L L bahr " <pulsarxp at embarqmail.com> wrote:
> 
> What is that, Jamie?  Are you using a coil of coax?  That is what I think I'll be using.
> Lee, w0vt
> 
> ----- Original Message -----
> From: "James C. Hall, MD" <heartdoc at nwtcc.com>
> To: towertalk at contesting.com
> Sent: Friday, August 1, 2014 12:21:10 PM
> Subject: Re: [TowerTalk] Recommendations for Purchasing a short 2 Element 40    Meter
> 
> I quit using the old B-1 balun. I use the "Ugly balun" on all antennas. Works extremely well with no heat degradation.
> 
> 73, Jamie
> WB4YDL
> 
> Sent from my iPad
> 
>> On Aug 1, 2014, at 11:36 AM, "Dale Drake" <daleaa1qd at gmail.com> wrote:
>> 
>> 
>> I had a recent bad experience with the Cushcraft XM-240.  The present
>> manufacturer had changed the U channel design from the original when it was
>> made by the NH company.  The original design ( according to the guy that
>> actually designed it) used a heat treated aluminum channel but the "new"
>> design uses a thinner channel formed from sheet in a brake ( not heat
>> treated). 
>> 
>> Mine was of the newer design and the wind ( 40-50MPH gusts from the remnants
>> of Bob) tore the 1/4" hex head cap screw heads right through the U channel
>> on one side and left the element dangling.  I called the manufacturer in MS
>> who said they had never heard of that failure but they sent me a new U
>> channel for free.  I put large stainless fender washers under the heads of
>> the 1/4" cap screws this time to spread the stress out more and so far so
>> good.  If I was to do it over I would replace the less rugged U channel with
>> something more like the original design.
>> 
>> If you want to see the pics email me directly aa1qd at arrl.net
>> 
>> Also if you plan on 1.5KW AM I would not use the stock balun as it is like
>> to fail with that much heating from what I've heard from other hams.
>> 
>> Dale 
>> AA1QD
>> 
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