Table 1 and Table 2
show that the transformer works well at 160- and 80- meter Bands,
fair at 40- and 20- meter Bands and bad beginning from 17- meter
Band. Of course it is possible play with quantity of the turns
but anyway it should be difficult to make a real broadband transformer
that covers 160- 10- meter Bands. So I gave up attempt to use
RF transformer on TV Yoke core at my Beverage Antenna.
In my parts box there was a symmetrical Balun from LDG. Figure 8 shows the Balun.
Some time ago I experimented with the Balun.
However for that time it just took place in the box waiting for
a new application. Time is come. The Balun
had strong plastic cabinet with socket SO- 239 on it from one
side and two terminals (for antenna and for ground) at another
Figure 7 Unsymmetrical RF Transformer 1:9 on TV Yoke
A ferrite ring was used on the Balun.
The sizes of the ring were suite for transformer 1:9 that could
work at 100- Wtts RF power going through. It was not hard reworked the
Balun to unsymmetrical RF transformer
1:9. Additional wire in Teflon insulation was coiled between turns
of the Balun. Then the wires were connected according to Figure 5.
9 shows the unsymmetrical RF transformer 1:9. The transformer
was tested. Table 3
shows data for the transformer loaded to Resistor 440 Ohm the measurements
made by MFJ- 259B.
Figure 8 Balun RBA- 1:1 from LDG
Table 4 shows data for the
transformer loaded to home brew Resistor 440 Ohm (shown
at Figure 3) the measurements made
by MFJ- 259B. As you can see the transformer works well from 160-
to 10- meter band. It is possible play with quantity of the turns
to move low SWR up or down inside the 160- 10- meter Band. However,
I did not do it and leaved things like this.
Figure 9 Unsymmetrical RF transformer 1:9 on the Base of Balun RBA- 1:1