Message-ID: <20071104154652.7hhjn8vlr734gos4@webmail3.kuleuven.be>
Date: Sun, 04 Nov 2007 15:46:52 +0100
From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: rsgb_lf_group@blacksheep.org
References: <000701c81ede$3af050e0$1ae4fc3e@g3kev>
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Subject: Re: LF: CLASS D and E
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Hello Mal,

with my 136kHz PA (variant of the G3YXM Class-D push-pull) I get 450W =20
output with 56V/9.5A supply, thus 85% efficiency.

I once tried a 50W class-E PA and got over 90% efficiency with correct =20
load (50 Ohm). But the efficiency of the class-E was very sensitive to =20
mismatch and for higher power levels the required values of L,C and =20
supply voltage were rather inconvenient.

Regarding components: I use coils wound on a thin PVC former (with =20
sufficient thick wire) and polyprop capacitors.
As both in class-D and class-E amplifiers the FET's are used as switch =20
(on/off device) they must be fast enough en have a low on-resistance. =20
The higher the frequency the faster it needs to be.

73, Rik  ON7YD

Quoting hamilton mal <g3kev.ham@virgin.net>:

> Hi all
> Class D and E amplifiers are supposed to give around 80/90 % efficiency. H=
as
> anyone actually achieved these figures. It seems anything above 60% is har=
d
> to arrive at using normal coils/capacitors.
>
> 73 de  Mal/G3KEV
>
>
>



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