Return-Path: Received: from rly-dc04.mx.aol.com (rly-dc04.mail.aol.com [172.19.136.33]) by air-dc08.mail.aol.com (v126.13) with ESMTP id MAILINDC081-b194b0cf7eb1ce; Wed, 25 Nov 2009 04:25:15 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dc04.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDC045-b194b0cf7eb1ce; Wed, 25 Nov 2009 04:25:01 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NDE6h-0001ek-Hd for rs_out_1@blacksheep.org; Wed, 25 Nov 2009 09:24:15 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NDE6g-0001eU-LV for rsgb_lf_group@blacksheep.org; Wed, 25 Nov 2009 09:24:14 +0000 Received: from out1.ip06ir2.opaltelecom.net ([62.24.128.242]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NDE6f-00082T-Vh for rsgb_lf_group@blacksheep.org; Wed, 25 Nov 2009 09:24:14 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av0EAPeGDEtcGuLt/2dsb2JhbACCIi+LPgbIGIQ5BA X-IronPort-AV: E=Sophos;i="4.47,285,1257120000"; d="scan'208,217";a="263228941" Received: from unknown (HELO your91hoehfy9g) ([92.26.226.237]) by out1.ip06ir2.opaltelecom.net with SMTP; 25 Nov 2009 09:23:57 +0000 Message-ID: <000c01ca6db1$04873810$0301a8c0@your91hoehfy9g> From: "mal hamilton" To: "rsgb" Date: Wed, 25 Nov 2009 09:23:58 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Class E pa Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01CA6DB1.043FA7C0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-AOL-IP: 193.82.116.20 ------=_NextPart_000_0009_01CA6DB1.043FA7C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ref recent discussion on the subject. I use a class E pa on 500 kcs and never get any trouble. As a general guide use high voltage fets and the fet V should be rated= at about 5 times the supply V and current about 3 times. You arrive at class E by careful design not by accident.=20 Having designed and built the PA for the required power and load R usu= ally 50 ohms adjust into a DL for correct waveform as displayed on a= 'scope, this is important otherwise V spikes and instability will kil= l the fet.=20 Install a suitable antenna and match it with a suitable atu to 50 ohms= so when you connect the TX/PA to the antenna they both match. Check the wave form again and any slight mismatch should be adjusted= by the antenna atu and NOT the pa.=20 The load does not have to be 50 ohms but this is convenient when testi= ng with available test gear. High V fets give more realistic C and Inductor and R values. A good ra= nge for fets is a psu giving 40 - 100 volts ie fets 500volts and a sui= table current rating depending on your power. requirements ie if you= need to draw 5 amps the fet should be rated 15 amps. These are the general guidelines and work well for me. Most amateurs seem to use class D amps whereas class E are rare. de Mal/G3KEV ------=_NextPart_000_0009_01CA6DB1.043FA7C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Ref recent discussion on the subject.=
 
I use a class E pa on 500 kcs and nev= er get any=20 trouble.
As a general guide use high voltage= fets and the=20 fet V should be rated at  about 5 times the supply V and current= about 3=20 times.
You arrive at class E by careful desi= gn not by=20 accident.
Having designed and built the PA for= the required=20 power and load R usually 50 ohms adjust into a DL for correc= t waveform=20 as displayed on a 'scope, this is important otherwise V spikes and ins= tability=20 will kill the fet.
Install a suitable antenna and match= it with a=20 suitable atu to 50 ohms so when you connect the TX/PA to the antenna= they both=20 match.
Check the wave form again and any sli= ght mismatch=20 should be adjusted by the antenna atu and NOT the pa.
Th= e load does not=20 have to be 50 ohms but this is convenient when testing with available= test=20 gear.
High V fets give more realistic C and= Inductor and=20 R values. A good range for fets is a psu giving 40 - 100 volts ie fets= 500volts=20 and a suitable current rating depending on your power. requirements ie= if you=20 need to draw 5 amps the fet should be rated 15 amps.
These are the general guidelines and= work well for=20 me.
Most amateurs seem to use class D amp= s whereas=20 class E are rare.
 
de Mal/G3KEV
 
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