[TenTec] Built in SWR meter bannans

[Rick - DJ0IP / NJ0IP]

OK, thanks Jim.

This has been a very educational thread.
I read your document once but I need to go back and take more time and study
it.
There is far too much information in it to be comprehended in a single
reading.

73
Rick, DJ0IP


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Wednesday, April 24, 2013 8:24 AM
To: tentec at contesting.com
Subject: Re: [TenTec] Built in SWR meter bannans

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
_______________________________________________
TenTec mailing list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec