Return-Path: Received: from rly-db05.mx.aol.com (rly-db05.mail.aol.com [172.19.130.80]) by air-db08.mail.aol.com (v126.13) with ESMTP id MAILINDB084-ac74b0d3e2211e; Wed, 25 Nov 2009 09:24:55 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-db05.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDB055-ac74b0d3e2211e; Wed, 25 Nov 2009 09:24:36 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NDImH-0003Dp-Oo for rs_out_1@blacksheep.org; Wed, 25 Nov 2009 14:23:29 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NDImH-0003Dg-3p for rsgb_lf_group@blacksheep.org; Wed, 25 Nov 2009 14:23:29 +0000 Received: from cavuit02.kulnet.kuleuven.be ([134.58.240.44]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NDImE-0003Hq-I5 for rsgb_lf_group@blacksheep.org; Wed, 25 Nov 2009 14:23:29 +0000 Received: from smtps02.kuleuven.be (smtpshost02.kulnet.kuleuven.be [134.58.240.75]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id 33FA251C003 for ; Wed, 25 Nov 2009 15:23:16 +0100 (CET) Received: from PC_van_Rik.fys.kuleuven.be (dhcp-10-33-85-106.fys.kuleuven.be [10.33.85.106]) by smtps02.kuleuven.be (Postfix) with ESMTP id 108C1F3862 for ; Wed, 25 Nov 2009 15:23:16 +0100 (CET) X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9 Date: Wed, 25 Nov 2009 15:23:23 +0100 To: "rsgb_lf_group@blacksheep.org" X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe In-Reply-To: References: <000c01ca6db1$04873810$0301a8c0@your91hoehfy9g> Mime-Version: 1.0 Message-Id: <20091125142316.108C1F3862@smtps02.kuleuven.be> X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,HTML_10_20=0.945,HTML_MESSAGE=0.001 Subject: Re: LF: Class E pa Content-Type: multipart/alternative; boundary="=====================_23863738==.ALT" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE, TO_ADDRESS_EQ_REAL 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 --=====================_23863738==.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed Hello Tony, >I'm still using a Derivative of the Design from G3YXM's class E 1KW TX on LF If you refer to the TX in http://www.wireless.org.uk/136rig.htm : this is a class D TX, not class E. I am also using a "G3XYM clone" on 500kHz (with a pair of IRFP350's). Running on 44V / 7 A it delivers just over 250W, about 82% efficiency. It seems very forgiving to mismatch, no FET failures so far (fingers crossed). But for testing purposes (antenna tuning) I run it on 13.6V (abt. 25W output) where it can handle any mismatch. 73, Rik ON7YD At 12:47 25/11/2009, you wrote: >Hi Mal >I'm still using a Derivative of the Design from G3YXM's class E 1KW >TX on LF. Recently I've built a TX for 500 kHz using the same >principle. It works great and delivers up to 500W. Unfortunately >only into a dummy load, because 500 kHz is still not allowed here in >Switzerland. But at least - I will be ready ;-) >73 de Toni, HB9ASB > >2009/11/25 mal hamilton <g3kevmal@talktalk.net> >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. >Having designed and built the PA for the required power and load R >usually 50 ohms adjust into a DL for correct waveform as displayed >on a 'scope, this is important otherwise V spikes and instability >will kill the fet. >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. >The load does not have to be 50 ohms but this is convenient when >testing with available test gear. >High V fets give more realistic C and Inductor and R values. A good >range for fets is a psu giving 40 - 100 volts ie fets 500volts and a >suitable 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 > > --=====================_23863738==.ALT Content-Type: text/html; charset="us-ascii" Hello Tony,

I'm still using a Derivative of the Design from G3YXM's class E 1KW TX on LF

If you refer to the TX in http://www.wireless.org.uk/136rig.htm : this is a class D TX, not class E.
I am also using a "G3XYM clone" on 500kHz (with a pair of IRFP350's). Running on 44V / 7 A it delivers just over 250W, about 82% efficiency. It seems very forgiving to mismatch, no FET failures so far (fingers crossed). But for testing purposes (antenna tuning) I run it on 13.6V (abt. 25W output) where it can handle any mismatch.

73, Rik ON7YD

At 12:47 25/11/2009, you wrote:
Hi Mal
I'm still using a Derivative of the Design from G3YXM's class E 1KW TX on LF. Recently I've built a TX for 500 kHz using the same principle. It works great and delivers up to 500W. Unfortunately only into a dummy load, because 500 kHz is still not allowed here in Switzerland. But at least - I will be ready ;-)
73 de Toni, HB9ASB

2009/11/25 mal hamilton <g3kevmal@talktalk.net >
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.
Having designed and built the PA for the required power and load R usually 50 ohms adjust into a DL for correct waveform as displayed on a 'scope, this is important otherwise V spikes and instability will kill the fet.
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.
The load does not have to be 50 ohms but this is convenient when testing with available test gear.
High V fets give more realistic C and Inductor and R values. A good range for fets is a psu giving 40 - 100 volts ie fets 500volts and a suitable 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
 

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