"Ian White G/GM3SEK" wrote in
If we're not clever enough to build an automatic ATU for a magloop,
it's
a sign that there's something about magloops we still need to
know...
====================================

We are able to analyse and predict the behaviour of magloops to any
required degree of precision.

What is missing is how both a magnitude-searching and phase-searching
circuit of an automatic tuner works when denied access to the
magnitude-searching component.

When manually adjusting a tuner it is obvious to the operator that the
controls INTERACT with each other. Both variable controls equally
affect both magnitude and phase. That much can be gleaned from
inspection of the circuitry.

For example, in the case of a T-tuner with two variable capacitors,
the operator cannot concentrate on one variable exclusively to the
other. He continually has to swap from one to the other and obtain a
balance by progressively closer approximations whilst keeping his eyes
on the co-called SWR meter.

An automatic tuner manages to complete the operation by varying both
controls simultaneously. But it is obvious from observation of what
the drive motors are doing, and the time taken to do it, that the
circuit is behaving just like a human operator. Occasionally the
motors even have to reverse and try again.

When denied access to either one of the two variable controls, the
automatic tuner doesn't know what to do next and would become lost.

If the desired impedance magnitude is known to be 50 ohms and is
somehow inserted in the circuit, this is of little assistance to how
the circuit behaves because when the main loop is off-resonance the
actual resistive component is miles away from 50 ohms yet the
automatic tuner is obliged to do something about it. But without the
ability to vary the diameter of the coupling loop, as I say, it is
lost.

So we need something different from and more sophisticated than the
conventional automatic tuner with its relatively simple magnitude and
phase-searching abilities.

I'll believe it when I see one which works.

Regarding your question about manual tuning up for maximum noise (or
signal) in the receiver, at the frequency set by the receiver,
reciprocity rules and fortunately, with modern transceivers, one can
bawl into the microphone and answer a CQ call with confidence that it
can be heard.

But Ian, you already know all this. I have the time and I just like
gabbing about it.

I trust you are comfortably settling down in your new country. I have
spent happy years, in bits, working in Scotland. It is a most
civilised place.
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Yours, Reg, G4FGQ