In a message dated 10/16/2002 10:49:20 PM Eastern Daylight Time,
Yeelaiseng@hotmail.com writes:
> Todds, Greetings
> How do you drive the Class-E solid state amp by using a Ham transciever for
> SSB
> operation? I understand Class-E is non-linear.
> Cheers Yee 9V1XK
>
Hi Yee, and others in the AMPS list, thanks for the interest in Class-E and
EER ( Envelope Elimination and Restoration). As best I understand it, EER is
a method that allows using a Class-E non-linear amplifier and a Class-S or
PWM audio amplifier to amplify an SSB signal in a Linear fashion. It sounds
complicated but what the system does is it samples or demodulates the
original SSB input signal into a separate phase-modulated RF signal by
hard-limiting the RF SSB input, and also a separate envelope-modulated AF
signal by using an envelope or diode detector on the SSB input. The constant
phase modulated RF signal is amplified by the Class-E RF amplifier which is
in turn modulated by the Class-S audio amp. When the phase modulated RF
signal in the Class-E amplifier is combined by simultaneously envelope
modulating the Class-E amplifier, an RF SSB output is reconstituted. Very
little RF drive is required from the SSB exciter or transceiver as it is not
actually "driving" the amplifier, just furnishing an SSB signal to be
sampled. Leonard Kahn of AM Stereo fame invented this system way back in
1952. It hasn't had much use until recently when high-efficiency became the
most important factor in amplifying an SSB signal. Some companies are making
all-in-one chips to control the Class-E amplifier and are using even more
modern "Delta" type modulators instead of the PWM or Class-S modulators. Once
you understand how the system works it is not all that difficult to build a
working system using a conventional Class-E amplifier and a Class-S or PWM
modulator. Dr. Fred H. Raab W1FR has written several papers on the EER
system and he has built a working system that he has used on 20 meters. You
might contact him if you are interested in looking into EER further. I had
some interest in it a few years ago and may look into it again. Hope this
info may help. 73 , Todd Roberts, WD4NGG.
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