Tom said:
>> I've seen it in a Z match, too. Not often - depends on the load. I
>> don't like the Z match anyway.
>With a reasonable load connected? No way!
It's quite easy in a Z match, although a lot depends on what you define as a
'reasonable load'. Think about one thing: if a Z match is so good, why are so
many of the commercial tuners T or L networks, when the Z match offers an
inherently balanced output, needs no variable inductors, can be made without any
switches, and has only two controls? In fact, I don't know of a commercial tuner
currently in manufacture that uses the Z match circuit.
>The reduction in efficiency is so gradual and slight no one would
>ever notice. Long before the power drops substantially, a
>component will fail.
Not sure I follow this. A component will fail because its VAR is exceeded in
some way - too many amps in a coil or capacitor, or too many volts across a
capacitor. The power that heats the component has to come from somewhere, and is
represented by less output power into the antenna. If I read you correctly, you
are suggesting that an output power drop of enough watts to cause the component
to burn up will not be noticeable. That suggests to me that the the tuner is
marginally rated. Of course, since you are not directly measuring the the number
of watts delivered to the antenna, it's a bit difficult to know just how many
watts are heating the tuner.
>People just need to learn to use the maximum possible
>capacitance that allows a match in a T network.
Of course. And to remember that the L network has a Q fixed by the ratio of
impedances, so that the extra component in a T can allow a much lower working Q
and so offer higher efficiency.
73
Peter G3RZP
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