[TowerTalk] Balun question

[David Gilbert]

First of all, thanks for the excellent information provided in your 
tutorials and reflector postings.

Per your comment below, I'm curious why I don't hear people using small 
diameter high-flexibility heliax for ferrite core baluns.  FSJ1-50 (1/4 
inch diameter) and FSJ2-50 (3/8 inch diameter) are both rated for a 
one-time bend radius of 1 inch, and either should handle a lot of 
power.  Short lengths (5 to 50 feet)  of both types regularly show up on 
eBay at well under a buck a foot.  Official Andrew connectors are also 
usually available, although at HF I don't think it should be a problem 
to simply hardwire the heliax to more common connectors.

Just curious.

73,
Dave  AB7E



Jim Brown wrote:
>
> So it is important to minimize the contribution of the coax that is outside 
> the cores. That contribution will be least if the diameter is smallest and 
> the turns are widely spaced. Increasing the diameter of the turns lowers 
> the resonant frequency of the choke a lot if you allow the turns to be 
> closely spaced outside the toroid stack, but not a lot if you do not. The 
> MOST important thing about winding these chokes is to keep the turns widely 
> spaced outside the stack. I recommend the smallest diameter that does not 
> compromise the recommended bend radius of the coax. 
>
> 73,
>
> Jim Brown K9YC
>
>
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