[TowerTalk] Fair rite materials for choke baluns

[Jim Thomson]

From: jimlux <jimlux at earthlink.net>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Fair rite materials for choke baluns


On 7/4/16 12:26 PM, Jim Brown wrote:

> An easy to build test fixture would be to use the choke as the end
> insulator of an end-fed center-fed dipole, as I've shown a couple of
> places, and shove high power at a high duty cycle into the dipole.

end-fed center-fed? What's that?  Do you mean coax into one side of UUT, 
then of the two leads on the other side, connect one to "half 
wavelength" of wire, and then what does the other side go to? The 
antenna support?  Or, since you're looking at common mode, both "output" 
wires of the choke go to the same place?

> http://k9yc.com/VerticalDipole.pdf

##  Look at the PDF.  Think of a dipole.. but turned vertical. 
With coax  going to center, and center conductor bonded to upper wire half, 
BUT, the lower wire leg, is replaced by the braid of the coax itself. 
A  CMC is inserted where the lower insulator would normally be placed on a wire dipole.
Below the  coax CMC... is just a continuation of the same coax... all the way back to the xcvr. 

##  it’s a unique way to build a vertically  polarized dipole...using a coaxial CMC  as the lower
insulator. It also places the CMC at an extreme high V / high Z point...and Im surprised the 
CMC  actually survives. 

Jim   VE7RF