[TenTec] OT: coax versus parallel wire, insulated wire for aerial

[Dr. Gerald N. Johnson]

On Mon, 2008-06-09 at 15:41 -0700, Jim Brown K9YC wrote:
> On Mon, 09 Jun 2008 10:39:31 -0600, Dr. Gerald N. Johnson wrote:
> 
> >I don't see the benefit of choking the outside of the coax AT the radio.
> 
> See my tutorial for the discussion of chokes as "egg insulators" in feedlines 
> to minimize their interaction with nearby antennas (especially verticals).
> 
> >Look up the specifications of ferrite toroids at Amidon. 
> 
> That's a TERRIBLE place to get specs or to buy them. Specs are next to 
> nothing, prices are very high.

At least the dimensions and permeability are listed at Amidon. The
material numbers may not match from Amidon as commonly used by hams to
Fair Rite parts and materials. Typical materials good up to 30 MHz in
ferrite have a permeability of 50 though those with permeability of  125
are good cores at 20 MHz and down, if you want reactance. If you want
loss you want a much higher permeability.

> Go the source (Fair-Rite) for specs, to my 
> website for measured data on chokes, and to industrial distributors to buy 
> the parts. 

And Mouser is that industrial distributor that is great to deal with.
www.mouser.com
> 
> 73,
> 
> Jim Brown K9YC
> 
73, Jerry, K0CQ