The link and the output coil do the balancing, I don't force
balance by grounding the center of the output coil, though that often works.
The grounding of the antenna side of the coil (typically between two caps
connected in series, with the the opposite end of the caps connected across
the ends of the coil) as seen in many link-coupled tuners has me baffled.
The EF Johsnon transmatch also uses a ground tap, but the output caps are
configured to create a voltage divider. I have looked for an explanation in
old versions of the ARRL Antenna Book as well as the Frank Jones Antenna
Books from the late 1930s. Cebik discusses it briefly but only in the
context that "it is optional." It seems to me that the tap should stay
ungrounded with balanced feeders With the center grounded, it also seems
that it creates a greater opportunity for unbalance. By removing the ground
tap, doesn't that provide the best opportunity to force equal current into
the line, while also keeping line current perfectly anti-phase?
Then I tap the feed line to the turns where it matches. And use a
variable link instead of the series capacitor on a fixed link.
I have seen this done to improve current balance, but what is the mechanism
by virtue of the grounded tap that assists with keeping line current
balanced?
Paul, W9AC
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