[TowerTalk] [Bulk] Cutting a FT-240 type 33...in half

[Jim Brown]

On Tue,2/10/2015 1:18 PM, Jim Brown wrote:
> There is dissipation in a ferrite core choke in the resistance coupled 
> from the ferrite core. It is the coax shield that gets hot, not the 
> ferrite (although the heat in the coax may be transferred to the 
> ferrite material). 

I should have added that the above dissipation is the result of common 
mode current, NOT differential mode current.  The power can be computed 
as I squared R or E squared divided by R, where R is the real part of 
the choking impedance (Rp in the parallel equivalent circuit), I is the 
common mode current, and E is the common voltage across the choke.

> This is in addition to the usual dissipation inside the coax 
> associated with the differential transmitter power. The coax must be 
> rated to handle both. 

73, Jim K9YC