Jim Brown wrote:
> The use of coax rated for high temperatures was part of the
> original work published on common mode chokes (current
> baluns) published by W1JR and W2DU. Further, it has been
> shown (by W8JI, among others) that mismatch is NOT a
> contributor to heating in a choke balun. Heating in a
> current balun is proportional to the square of the common
> mode current. An effective common mode choke (current balun)
> will add a very high resistive impedance in series with that
> common mode circuit, reducing that current to a small value,
> and making dissipation small.
My experience when feeding a balanced antenna with a common mode choke
at the transmitter end is the following: reducing the reactive component
at the balun terminals reduced heating. I am not sure why the common
mode current would be affected by canceling out the differential mode
reactance, so I am not sure this is the whole story.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|