Topband: Termination Transformer

Jim Brown jim at
Fri Jan 1 19:39:25 EST 2016

On Fri,1/1/2016 3:09 PM, Mike Waters wrote:
> John appears to be taking into account the impedance of the winding vs. the impedance that the winding is connected to (the 710 ohm line).

A review of how transformers work is in order. Except for stray effects 
(capacitance between windings, resistance in a core), transformers have 
no impedance of their own. Rather, they multiply the impedance connected 
to the other winding by the square of the turns ratio. If you measure Z 
of an ideal transformer with the other winding open circuit, you should 
see an open circuit (infinite Z). Real transformers have strays, so 
you'll see some high Z.

73, Jim K9YC

73, Jim K9YC

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