The Johnson Match boxes had a range of operation, but were unexcelled within
that range of impedances that they would match. One improvement I have seen
is to add a variable capacitor in series with the input as in a tuned link.
They are of course tapped "links" on a large coil.
Can't believe the other link tuners would be more efficient, as there would
be the same number of inductor losses. The Q and voltage rating of even
the 275 watt Matchbox are excellent, it was designed for 275 watts of 100
per cent AM modulated signal. The components would be considered linear
sized in today's equipment. I believe the voltage rating on the capacitors
was well over what they encountered in the worst matching cases.
The only advantage a true link brings is the DC isolation between the link
and tuned circuit.
73,
Stuart
K5KVH
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