--- On Tue, 7/14/09, Ron D'Eau Claire <[email protected]> wrote:
Note that using the lengths do not improve the performance, only the
impedance excursions involved and they can be handled by a wide range tuner
quite nicely.
That said, some tuners show excessive losses at extreme impedances even
though they may show a 1:1 SWR on the coax link to the rig. I use a homebrew
fully-balanced link-coupled tuner with my doublets that I have considerable
confidence in having low losses across its range and the ability to match
everything from a fraction of an ohm to many thousands of ohms. Using many
"commercial" tuners I'd be much more
concerned.
And well you should be. In the time leading up to the publication of my
"ladder line" paper (see another post in this thread) I had considerable
correspondence with Dean Straw, the ARRL antenna guru and editor. I introduced
the idea that tuner losses could be much higher than amateur folklore assumed.
While none of this was ever published (it may be more than coincidental) that
shortly thereafter there began to be articles published on the subject of tuner
losses (several by Frank Witt) and Dean's own software began to feature the
capability of calculating those losses.
I had also pointed out in that correspondence that the popular T-network tuner
with three variable components could be easily (more than likely) mis-adjusted
such that a match was achieved at a less than optimum condition as far as
losses were concerned. This has since been addressed
in other articles.
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