Richard, first I'll say that I did NOT find a survey, I've seen
statements to this effect. (See http://www.eham.net/articles/4424) Of
course, I've found statements to the contrary.

I'd like to collect some data points if people have actually measured
the input and output power of their tuner into various loads, and I'll
keep looking for real data.

I'd also like to focus my question about matching range and efficiency
and retract all the other questions for now. I realize reading your
response that I asked a bunch of general questions that were at best
ill-defined an at worst trolly-sounding.

Pick a topology, let's say the shunt L tee (CLC) because it's so
common. Assume your tuner (the one who tunes), human or
microprocessor, is smart enough to select the most efficient values of
C1, L and C2 if there happens to be more than one solution for a
particular set of impedances.

Let's say I have a range of impedances within which I can get a 1:1 50
ohm SWR: How about the interior of the rectangle between 5 and 1000
ohms resistance, -500 to 500 ohms reactance.

Then take the subregion of that rectangle where efficiency of the tuner
is greater than some value, say, 79.4% (so you're losing no more than
1dB in the tuner)

Here's one question:

Is that subregion really complicated, with lots of small spots where
you can get an efficient match right next to spots where you're dumping
lots of power into the tuner, or is the variation more smooth?

I'll leave it at that for now. I've got more questions that would pend
knowing the answer to that one.

I may have to sit down with one of the CLC tuner simulators and make
myself a plot.

Dan
N3OX












Richard Clark wrote:
On 28 Apr 2006 08:52:31 -0700, "
wrote:

Hi Dan,

There are so many red lights going on, this was impossible to pass up.

I've found some sources that say that the auto tuners tend to have a
wider efficient matching range than the typical manual tuner.

Unless "they" can tie this to known antenna impedances, such claims
are worthless. And for another, what are the "typical" tuners that
are being compared to? Its easy enough to say what they are if it was
easy enough to measure them to support this claim.

So it may have nothing to do with network topology, it's just that if
you can manage to match a very short unloaded whip with your typical
manual tuner, you're going to be out at the edge of the matching range
where it is quite inefficient.

Matching and effeciency are only distantly related. Using padding
resistors could pull any antenna into a match - not much efficiency
there.

What's the group experience with this? If it's true that the automatic
tuners tend to be more efficient for a given range of impedances, what
are likely reasons?

There's a sucker born every minute?

Can the typical auto tuner switch from LCL tee to CLC tee? Pi to Tee?

That would have seem to have answered itself if your survey of
different auto-tuners was useful. Barring these results being
obvious, it would seem you simply discovered the font of Marketing
hype.

Is it always going to be better to use a binary switched inductor and
capacitor system as opposed to a variable capacitor/tapped inductor
system?

Depends on the granularity. Binary could mean one of two, or one of
1024.

Maybe it's just that the latter usually gets shoved into a tiny box and
the inductor Q is ruined?

For auto-tuners, that should be evident - and a marked counter to the
claim of greater efficiency.

73's
Richard Clark, KB7QHC