[TowerTalk] Delta loop question

[Steve Hunt]

Tom,

Air cored chokes tend to be quite narrow-band - that means using the 
right number of turns of the correct diameter is critical to getting 
high choking impedance at your operating frequency. Even then, they are 
Reactive and can actually increase CM current in some applications.

The safer option is to wind the coax on a ferrite core - the number of 
turns is then less critical and its impedance will be Resistive if you 
choose the correct material. There are some choke designs here which may 
be suitable:
http://www.karinya.net/g3txq/chokes/

Those charts also indicate how narrow-band the air-cored chokes are.

Winding the coax on a ferrite core will have no effect on its 
differential-mode operation, so it will still operate OK as a matching 
section.

73,
Steve G3TXQ



On 25/02/2011 19:26, Tom Osborne wrote:
> H
> This might seem like a silly question, but I just put up a 15 meter delta
> loop and wanted to wind a RF choke coil at the antenna.
>
> I am matching the antenna with a 1/4 wave matching section.  Is is OK to
> wind this section into a coil for the RF choke, or wind it through a
> torroid?  I don't see where it would hurt anything, but not sure.  Thanks
> and 73
> Tom W7WHY
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>