Here is my attempt to build an 1:4 HF Balun. There are lots of web page available on how to construct a balun. One of them is from KN9B page.
There are 2 kind of Balun, a Voltage Balun and a Current Balun.
Voltage balun are flexible in the impedance ratio, where you can build almost any transformation ratio. While for current balun, the ratio is limited.
I have a toroid with OD=23mm and it found that the toroid has AL of 540.
So, for HF 80m balun, the minimum inductance is 23uH. This inductance can be obtained with 7 turn.
A Voltage balun is constructed by making bifilar winding as shown in picture below :
My Current balun uses two bifilar wound stacked like picture below :
The performance is acceptable where SWR is below 1:1.2 for the entire HF Band. Here the simple test using R=200 ohm at 40m band.
YD1GCL and YD1MRI has tested this balun with good result for power up to 100W. So, I am happy that this home made balun can perform as expected.
Making balun is not difficult, there are lots of balun available at the market which cost more than if you build one on your own. I have seen an commercial balun which perform worst than this home made balun. So, why buy ?? Keep experiment and homebrewing ....
There are 2 kind of Balun, a Voltage Balun and a Current Balun.
Voltage balun are flexible in the impedance ratio, where you can build almost any transformation ratio. While for current balun, the ratio is limited.
I have a toroid with OD=23mm and it found that the toroid has AL of 540.
So, for HF 80m balun, the minimum inductance is 23uH. This inductance can be obtained with 7 turn.
A Voltage balun is constructed by making bifilar winding as shown in picture below :
My Current balun uses two bifilar wound stacked like picture below :
The performance is acceptable where SWR is below 1:1.2 for the entire HF Band. Here the simple test using R=200 ohm at 40m band.
YD1GCL and YD1MRI has tested this balun with good result for power up to 100W. So, I am happy that this home made balun can perform as expected.
Making balun is not difficult, there are lots of balun available at the market which cost more than if you build one on your own. I have seen an commercial balun which perform worst than this home made balun. So, why buy ?? Keep experiment and homebrewing ....
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