[TowerTalk] Topband: 160 meter elevated vertical

[Jim Lux]

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.