[Amps] reducing the reactance of a wirewound resistor

[Hsu]

Please Google  Aryton-Perry winnding.I have use this way to wind a no
inductance dumy load for my first 100W TRX.
    73!Hsu

-----原始邮件----- 
From: Angel Vilaseca
Sent: Friday, February 03, 2012 4:23 PM
To: amps at contesting.com
Subject: [Amps] reducing the reactance of a wirewound resistor

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?

73

Angel Vilaseca HB9SLV
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