[TenTec] Built in SWR meter bannans

[Jim Brown]

On 4/23/2013 10:27 PM, Rick - DJ0IP / NJ0IP wrote:
> OK, I got the point on too little common mode impedance causing the damage,
> but there is nothing wrong with using Teflon covered wire, is there?

Dielectric constant will be different, which changes the capacitance, 
which changes the shape of the Z curve.  THHN yields a particularly nice 
Z curve. I haven't looked at Teflon, which might be fine too, or maybe not.

Fundamental truths.

1) The heat is produced in the WIRE, NOT THE CORE. It is the WIRE that 
gets hot.

2) Heat is produced by common mode current in the resistance of the 
parallel resonant circuit. P is I squared R, and P becomes smaller twice 
as fast as R becomes larger (because I is squared in the equation).

3) Chokes fail because R is too small. Period.  R depends on the core 
material and the physical details of the winding.

73, Jim K9YC