WB6ZQZ Triple Ratio Balun

Testing the TRB (Triple Ratio Balun) with the Autek RX Vector Analyst

TRB Construction

The first TRB I built is shown in the photos below. I wound it with four quadrifilar turns and 8 bifilar turns.

When bending the wires, avoid any more bending than necessary as it work hardens the wire and makes the process harder. Tighten up the turns against the core as best you can. The way I did it is to loop the next turn through the core before tightening the loop, rather like a snake loosely winding through and then tightening turn by turn. Avoid bending the wire back and forth. Imagine a snake making coils through the core and tightening after the next turn is around the core.

8 Bifilar Turns.

4 Quadrifilar Turns.

The first two connections.
From lower right toward left the wires are 1,3,5,7.
The second set a bit higher up and slightly left are 2,4,6,8
Wire 3 connects to wire 8 in the upper right and continues for the 12 ohm output.
The lower left connection is wire 7 to wire 2. That connection appears to need a bit more solder.
Get the enamel completely off the joints to facilitate good solder joints.

The third connection (upper left) connects wire 5 to wire 4 and on out to the 25 ohm output.

Combined Baluns. Upper righ wire pair is input.
Next 3 wires down, top down, are common between baluns, which curves back and connects over the center of the core.
Next down is the 1:1 50 ohm line between baluns with the tap heading to the 50 ohm banana jack.
Next downward are the 25 ohm and the 12 ohm outputs heading off toward the right where they will connect to the banana jacks.

Ready for Installation. Wires are formed to meet the connections in the endcap.

Endcap drilled and ready.

Endcap from the inside, connectors installed.

Completed Endcap. Input is SO239 near the top. Upper black Banana Jack is Output Common.
Lower Left black jack is 50 ohms. Center red is 25 ohms. Right red is 12 ohms.

TRB Wiring Configuration


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You may email author Alan Biocca via wb6zqz at qsl.net