[Amps] Class E amd and MRF492

[Bill Fuqua]

     I have seen variations of the DAF that compared rectified output and 
input voltages to set  control the screen grid. The question always remains 
what of the intermodulation products even though the envelop appears to be 
just fine. This has always been a problem and I wonder if someone has 
actually made IMD measurements.
    The phase correction is particularly necessary for digital signals in 
the polar loop system.

73
Bill wa4lav


At 10:24 AM 3/9/2005 -0500, you wrote:
>
>In a message dated 09/03/2005 14:14:18 GMT Standard Time, wlfuqu00 at uky.edu
>writes:
>
>The  polar loop system is a variation of the DAF amplifier.
>
>
>I think that there's a fundamental difference between the DAF and  polar
>loop. The major one is that polar loop has a negative feedback 
>mechanism,  while
>the DAF runs open loop.
>
>Now if you modulated the supply volts to the Class E amplifier in sympathy
>with the envelope so that it was always hard switching, you should be able 
>to
>keep the efficiency up. It would give an interesting problem in doing a
>suitable switching modulator - by rule of thumb, I'd expect it to need 
>a  bandwidth
>of around 30kHz and a switching frequency in the hundreds of kHz,  which
>would be interesting EMC wise, too. Anything else and you'll lose  efiiceincy.
>
>Perhaps a better approach might be to use two Class E stages in a  Callum
>modulator
>
>73
>
>Peter G3RZP
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