> >Tuners need only a reflectometer to indicate when zero reflected
> >power is obtained during adjustment.
>
> Generally speaking, I agree with Rich. However, some tuner circuits
> can be tuned up to have a very low input SWR and no output, with the
> tuner losses being transformed up to 50 ohms. The result is that the
> smoke gets let out of the tuner parts - or the solder out out of the
> joints! Of course, these tuners can also be tuned to have a very low
> input SWR because they're doing the job correctly.
I hear that rumor repeated, but I've never been able to find that in
any tuner I have ever seen.
What does happen is there is a smooth and gradual reduction in
efficiency as the Q is made higher, but that reduction is so slight
no one would notice the loss in power transfer. Even the smallest
amount of loss will destroy a tuner if power is high, since the loss
is generally confined to one small area of the inductor. Typically as
little as 50 watts of power loss will can ruin an inductor on
sustained CW or RTTY operation.
It also would be impractical to measure power in the varying load
part of the system, and most people find the power meter
convenient. I use ATR30's here all the time, mostly because it has
a good peak reading meter and antenna switch inside. When I
need to, I can "touch up" a high SWR to work a WARC band or a
frequency out of range of one of my narrow antennas. It is a multi-
function advantage to have a good directional coupler.
73, Tom W8JI
W8JI@contesting.com
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