[Amps] FW: Power factor correction on tube amps

[Jim Brown]

On 3/7/2013 3:49 PM, KA4INM wrote:
> No, the transformer is all inductive and the diodes conduct for most 
> of the sine wave, but not all, at that transition the current changes 
> abruptly causing distortion. 

NO!  Only the "imperfections" in a transformer are inductive (and 
capacitive, and resistive). The relatively inductance that we see in the 
circuit is "leakage inductance" -- and is due to the relatively small 
part of the flux from one winding that does not couple to the other. For 
any decent transformer, it's a very small fraction of the inductance of 
a winding.

The equivalent circuit of a transformer is complex -- in addition to the 
leakage inductance, there's resistance in the wire, resistance coupled 
from the core, capacitance between turns, capacitance between windings. 
At power frequencies though, we don't see the inductance or capacitance, 
only the resistance. And if we look into one winding, we see the load 
impedance on the other winding multiplied by the square of turns ratio.

73, Jim K9YC