W2DU's device is not a balun. It has no ratio - it is just a choke.
It behaves in the same way as a single bifilar winding on a ferrite
rod, or on a ring.

But a choke does not necessarily prevent longitudinal standing-wave
currents on the line. It merely shifts standing waves to other
positions along the line.

If a choke is located at a current minimum it may serve no useful
purpose at that operating frequency.

A true balun transformer, whatever its ratio, by itself provides no
obstruction to longitudinal currents. There can be a direct connection
between the line and antenna.
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Reg, G4FGQ.