Question: How does the internal balun in a link coupled tuner
compare with the a 'tri-filer' balun such as used in the
Nye-Viking MB-V-A?
A link coupled tuner IS a balun. It is not a tuner WITH a balun. It is
essentially a tunable air core transformer. Usually (perhaps always) a
link coil of just a few turns is the primary of the transformer, fed by
the UNbalanced transmission line (coax) from the source (transmitter).
The secondary generally has a many turns, perhaps tapped for band
switching (as in the case of a Johnsom Matchbox) and is connected to the
BALanced transmission line to the load (antenna). The transformer
windings have variable capacitors connected to them to make it tunable.
In the Johnson Matchbox only the secondary has tuning capacitors. Other
variations may also have a tunable primary. In the Johnson Matchbox the
secondary is actually two coils, with the primary link in the middle of
them. Or perhaps you could say it is one big center tapped coil, with
bandswitching taps at both ends.
My labeling of primary and secondary assumes that you are transmitting.
Turn the labels around for receiving.
DE N6KB
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