Re: balun test


From: Karl F. Larsen (
Date: Sat Sep 28 2002 - 16:59:38 CDT

Hi Jose, I will write it to you and the QRP-L list.

        I wish I could draw a picture but you can't do it with a e-mail.
So in words picture this:

        Hook the output of the balun to a MFJ Antenna Analyser and
assuming the balun is a 4:1 type put a load made from 2 each 100 ohm 1/4
watt resistors in series.

        If the resistors are accurate your MFJ should indicate the
impedance to be 50 ohms with no reactive components. You might have some
small reactive component caused by the balun.

        Now observe that the junction of the two resisters is the center
tap of a balanced load. Now if the load is really balanced, you should
be able to run a wire from the center tap to ground (the shield of the
coax output of the balun) and there will be NO effect of any kind.

        I use a short clip-lead and just hold the end to ground on
ground. Watch the SWR while touching ground. It might change just a tiny
bit and be good. On a bad balun the swr will jump high and show that the
load is not balanced.

On Sat, 28 Sep 2002, JOSE VICENTE wrote:

> Karl;
> Can you please tell me how to do the balun test with 2 resistors?
> Thanks, Joe py2auc
> You wrote:
> I ran the test where you make a load with 2
> series resitors and ground the center

               - Karl Larsen k5di Las Cruces,NM Az ScQRPions -

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