[TowerTalk] homebrew 1:1 current balun

[Jim Thomson]

Date: Mon, 30 Nov 2015 15:11:19 -0800
From: Jim Lux <jimlux at earthlink.net>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] homebrew 1:1 current balun

On 11/30/15 9:17 AM, Jamie Tolbert wrote:
> What tpe beads do I need, 43 or 73? length? 4 ft, 100 beads seems awfully long.....
>
> ____________
I use 31 mix for this kind of choke application.

what is your operating frequency?

http://audiosystemsgroup.com/NCDXACoaxChokesPPT.pdf
see pages 22-25
73 is better in general, 43 is ok for low frequencies
31 isn't great for bead baluns..


Have you considered using a 2.4" toroid core(s) and running multiple 
turns of the coax through it.  I can get about 10-12 turns of 1/4" 
diameter coax (RG58 type) through those cores. I think you can get 3-5 
turns of 0.405" coax (RG213 type) through it.

There's a fairly decent cookbook for this kind of thing, with all the 
measurements on actual chokes, etc. in Chapter 7 of 
http://www.audiosystemsgroup.com/RFI-Ham.pdf

##  You can easily get  7 turns of  RG-213U  through 2.4 inch OD  cores.   Ditto  with RG-393. 
To make for a more compact balun assy,  3-8 cores can be positioned  on either side, like
binocular fashion, then tightly wound...if using  RG-213U  or   RG-393. 

##  If using small coax, use  RG-303, or  RG-400  etc. 

Jim   VE7RF