Date: Mon, 30 Nov 2015 15:11:19 -0800
From: Jim Lux <jimlux@earthlink.net>
To: towertalk@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
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