LAB PROOF (1)

By G3TXQ

Photo by G3TXQ

 

Single Core 4:1 Guanella Balun

 

Built with two 1:1 Guanella Baluns wound on the same toroid core.

 

The Input is through the coax on the right, the Output is on the left.  A scope probe is attached to each side of the Output.

 

The misured results are shown in the picture below.

Photo by G3TXQ

 

The screen shot on the left shows the signals on the two Output terminals of the single core 4:1 Guanella.

 

The RF on the terminal shown in the lower portion of the screen is 3x as strong as the RF on the terminal shown in the top of the screen.

 

THIS IS A 3:1 IMBALANCE

 

THIS DEVICE IS NOT A BALUN!

 

According to Steve, G3TXQ:

 

Because of Sevick's pre-occupation with differential-mode performance he never spotted that effect. In fact he made lots of DM measurements - DM impedance, phase delays etc - but with a *floating* load; and as we all know, if you have a floating load you don't need a balun to maintain current balance :)

 

The simple fact is that a 4:1 Guanella balun wound as two 1:1 chokes on a common core will force voltage and current *imbalance* with any non-floating load; I don't call that "working" !

 

For a 4:1 Guanella balun to "work" properly and drive equal currents into any load, the CM voltages of the two chokes must be able to take up different values; they can't do that if they share the same magnetic circuit.

 

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