[Top] [All Lists]

[Amps] reducing the reactance of a wirewound resistor

Subject: [Amps] reducing the reactance of a wirewound resistor
From: Angel Vilaseca <>
Date: Fri, 03 Feb 2012 09:23:20 +0100
List-post: <">>
Hi all

I have a nice large 50 ohms wirewound resistor, which I would like to 
use as a dummy load. Problem is, it is inductive of course.

To cancel the inductive reactance I was thinking of winding some 
enameled wire all along over the resistor, with as many turns as the 
resistive wire, solder the enameled wire to the resistor terminal at one 
end and feed the RF at the other two separate terminals (wire and 
resistor) at the other end.

The idea is that the inductive reactance of the resistor winding and the 
enameled wire winding will cancel each other. With some care and 
measuring gear the remaining reactance could be very low. The assembly 
would then behave almost as a pure resistance.

Of course, care should be taken not to reach too high temperatures, 
because the enameled wire would then be damaged.

Also, the added winding should be wound in the appropriate diraction ( 
CW or CCW depending of the winding direction of the resistive wire) 
otherwise the two inductances would add instead ao canceling each other.

Has anyone alredy tried this?


Angel Vilaseca HB9SLV
Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>