Stefan,
Sounds very interesting; would the function of the DC input primarily be to
reduce output amplitude during the microseconds-long transitions between
QRSS states or EbNaut or OP32 states? Or to modulate? Or to keep the
transformer below but near to saturation for click suppression?
73,
Jim AA5BW
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of DK7FC
Sent: Tuesday, April 18, 2017 12:18 PM
To: [email protected]
Subject: LF: A transductor for power regulation?
Hi all,
I'm just thinking about transductors and find them them quite fascinating
again. I read a bit Wikipedia and thought about the use as a steerable
transformer.
Imagine you have a hard switching class D PA, H bridge or so. The output is
a constant voltage source and it is no problem to connect no load, as long
as a proper type of low pass filter is used.
Then imagine a simple 1:1 ferrite transformer, 50 Ohm to 50 Ohm. The
transformer has a 3rd winding for a DC current (to compensate the AC
component transformed from the RF windings, 2 cores must be used, which are
in parallel for the RF and anti-serial for DC).
Then i can saturate the transformer with the DC so the µr falls down to 1.
With this arrangement i could build a linear PA out of a switch mode PA,
even a fast one, which avoids key-clicks, at least in QRSS-3 (you remember
the mode) or OP32 or even EbNaut on LF?
Sounds like an interesting experiment at least. The question is how warm the
transformer would become when the RF output current is permanently reduced
to 50%.
Has someone ever tried that on LF/MF?
73, Stefan
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