-----Original Message-----
From: phil <phil@invest.fsbusiness.co.uk>
To: Steve Thompson <rfamps@ic24.net>
Cc: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: 18 February 2000 03:12
Subject: Re: [AMPS] interesting SS amps
>
>Steve,
>
>>What does it do into 3:1 all phases? With such a big FET you might get
away
>>with it, but I'd wear safety specs to stop bits of exploding package going
>>in my eyes :-)
>The answer is, as with any amp, bipolar, fet class-e, etc etc is how
>long is a piece of string.
>
>In this case it's usually down to how much headroom you have for the
>device on Vds at the power level your operating and how much gets added
>through the reflected component due to vswr, and also with the reflected
>phase angle.
>
>I'm sure you really knew all this Steve.
At least some of it :-)
It's some years since I last looked at class E. Devices have changed since
then, and the problems I saw might have reduced. It wasn't just voltage I
was thinking of - to get the really high efficiency, you ended up using a
small device so as to get rapid switching. If the load conditions alter,
dissipation rockets and the device goes bang - sometimes quite
spectacularly. If you use something with more dissipation so it can cope,
you lose switching speed and gain, and the efficiency drops closer to a
'regular' circuit.
Careful with that ATU...
Steve
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