[TowerTalk] Topband: 160 meter elevated vertical

[Steve Hunt]

You can just fit 17 turns of RG-58 on a FT240-31 toroid, and that will 
give you over 8000 Ohms CM impedance on 160m

Steve G3TXQ




On 20/10/2012 16:56, Jim Lux wrote:
> On 10/20/12 8:47 AM, Cqtestk4xs at aol.com wrote:
>> Along with that line of thinking...using RG58 on a 4 inch core.  
>> About  how
>> many turns?  My thinking is around 25 or so.
>>
>
> why not 4 or 5 turns on a 2.4" ferrite/powdered metal core?  4" PVC 
> core is a foot per turn, 25 turns is 25 feet of coax (which I grant 
> you probably already have), but say it's 0.25/ft.  that's 5-6 bucks 
> worth of coax against a $5 ferrite core, which will be more broadband, 
> higher choking impedance, physically smaller, etc.  Air core chokes 
> don't have a lot of resistive impedance: you're depending on their 
> inductive reactance, and that's subject to cancellation from parasitic 
> C, etc.
>
> You'd have to check K9YCs writeup to see what an appropriate material 
> for the core would be.  #31 is the sort of general go-to material for 
> ham band use, but there might be something better for lower frequencies.
>
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