Hello Group,
Hi Rik,
Rik Strobbe wrote:
Charmed by the simplicity (only 4 components) and the high efficiency of
class E amplifiers I decided to do some experiments with these.
Not at power levels >200Watts.
So I wonder if someone already has experience with a high-power class E
amplifier ?
I know this article. Running class-E is not a question of
high voltage at first. Class-E means to load a current fed
switch (here MOSFet and choke) such that Ud AND dUd/dt at
switching time are BOTH zero ("soft landing"). This is the
key to class-E!
So you have to deal with impedance i.e. "right" phase shifts
at input of your output network. What kind of output circuit
you want to use doesn't matter if it provides "soft
landing". Of course this is easier to achieve at somewhat
higher voltages. Class-E designs are very robust since of
it's high capacitance at load. I killed most Fets from Gate
side (Ugmax +-20V...).
I observed the following:
One disadvantage is that due to the low resonance
frequencies of the output filter circuits the class-E design
has a tendency to "stutter" on sub harmonics if mismatched
to the "inductance plane" of the smith diagram. But I never
observed this, mismatching the PA resistively only.
I collected some other articles on class-D/E (the well known
QST article included) there:
ftp://ftp.rz.uni-kiel.de/pub/nephro/nephlab/lp/MosFet-PA/
Look for: ClassE.pdf, PA_10MHz.pdf, QST.pdf, RFdesign.pdf.
(Acrobat Reader or clone required...)
54°16'N / 10°04'E, JO54ag
73 es gl de Peter, DF3LP
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