Return-Path: Received: from mtain-dl08.r1000.mx.aol.com (mtain-dl08.r1000.mx.aol.com [172.29.74.214]) by air-de08.mail.aol.com (v129.4) with ESMTP id MAILINDE083-5ec04d3b23f5f8; Sat, 22 Jan 2011 13:37:41 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl08.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6C98B380000BC; Sat, 22 Jan 2011 13:37:40 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PgiKT-00061t-Ic for rs_out_1@blacksheep.org; Sat, 22 Jan 2011 18:36:53 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PgiKT-00061k-0W for rsgb_lf_group@blacksheep.org; Sat, 22 Jan 2011 18:36:53 +0000 Received: from out1.ip08ir2.opaltelecom.net ([62.24.128.244]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PgiKQ-0008Mq-Ew for rsgb_lf_group@blacksheep.org; Sat, 22 Jan 2011 18:36:52 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AhoFAJuyOk1Ok86T/2dsb2JhbACCQaItc70PhVAEgV+NAYJe X-IronPort-AV: E=Sophos;i="4.60,363,1291593600"; d="scan'208,217";a="477444092" Received: from unknown (HELO xphd97xgq27nyf) ([78.147.206.147]) by out1.ip08ir2.opaltelecom.net with SMTP; 22 Jan 2011 18:36:44 +0000 Message-ID: <00ad01cbba63$505ecd70$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Sat, 22 Jan 2011 18:36:41 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: RE: Thick Litz wire needed, and more on class E PA development Content-Type: multipart/alternative; boundary="----=_NextPart_000_00AA_01CBBA63.5001E060" 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-global-disposition: G x-aol-sid: 3039ac1d4ad64d3b23f467d6 X-AOL-IP: 195.171.43.25 ------=_NextPart_000_00AA_01CBBA63.5001E060 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Around 10 uH is the right value for L on 500. This is what I use and= it does not get HOT. g3kev ----- Original Message -----=20 From: Rik Strobbe=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Saturday, January 22, 2011 6:31 PM Subject: LF: RE: Thick Litz wire needed, and more on class E PA deve= lopment Hello Andy, with 9.3UH the class E amp must have a rather high Q (12 ?). Maybe= a lower Q (and more or less proportional lower L) might help ? 73, Rik ON7YD - OR7T ----------------------------------------------------------------------= -------- Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksh= eep.org] namens Andy Talbot [andy.g4jnt@gmail.com] Verzonden: zaterdag 22 januari 2011 18:14 Aan: rsgb_lf_group@blacksheep.org Onderwerp: LF: Thick Litz wire needed, and more on class E PA develo= pment Is there still any of the really thick Litz wire from the old Decca= stations around? I'm after about 3 to 3.5 metres of whatever is ava= ilable that is thicker than 3mm, and preferably nearer 3.5mm diameter.= Enough to make a 9.3uH coil The Tank coil in the latest version of the class E PA under test is= now the power-determining item. At 450 Watts output the heatsink wi= th fan is COLD - but the coil annoyingly smells of hot varnish. It is wound with the cotton covered Litz, about 2.5mm overall diamet= er which itself is a big improvement over the plastic covered stuff I= was using for the breadboard. But, I have the surreal situation that= as teh coil gets hot, teh wire expands, inductance falls and due to= the nature of the combined Tank + L-Match circuitry causes a resultin= g increase in powser output - leadign to higher dissipation and you ca= n guess what will eventually happen if left unchecked. One soluition will be to duct air from the fan through the coil, but= I'd feel happier if loses were lower to start with. At reduced Vdd it reaches stability running at 400 Watts without get= ting too hot and increasing itself spontaneously. Efficiency, by the way, variously measures at 86 - 94%. So I'll say= around 88%. Hard to believe, but I have been over everything and= double checks, and can't get teh value below 84% however much I try= to push errors in the worst direction. The FETs are now a pair of IRFP360, and the driver chip had to be= replaced - the poor ICL7667 just went bang and split itself open driv= ing them. The copper of the PCB tracks running under it became discol= oured so it must have bene running very hot before dying Now using a= pair of SMT TC4420 devices - one per FET - with additional copper he= at dissipating fins on the PCB. They've survived so far. Its been delivering 320 Watts for an hour now off a 37V rail, so at= that power level is certainly reliable; brief forays up to a 55V rail= gave slightly over 700 Watts - and I could see current rising as I wa= tched due to the coil expanding, so didn't hold it there for long, but= does mean the PA as it stands could be used with AM/envelope modulati= on. The shack is getting quite warm now ! A second chapter to the write-up will appear in due course Andy www.g4jnt.com ------=_NextPart_000_00AA_01CBBA63.5001E060 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Around 10 uH is the right value for= L on 500. This=20 is what I use and it does not get HOT.
g3kev
 
----- Original Message -----
From:=20 Rik Strobbe
Sent: Saturday, January 22,= 2011 6:31=20 PM
Subject: LF: RE: Thick Litz= wire needed,=20 and more on class E PA development

Hello Andy,
 
with 9.3UH the class E amp&nb= sp;must have a=20 rather high Q (12 ?). Maybe a lower Q (and more or less=20 proportional lower L) might help ?
 
73, Rik  ON7YD - OR7T<= /DIV>
&= nbsp;
Van: owner-rsgb_lf_group@bla= cksheep.org=20 [owner-rsgb_lf_group@blacksheep.org] namens Andy Talbot=20 [andy.g4jnt@gmail.com]
Verzonden: zaterdag 22 januari 2011= =20 18:14
Aan: rsgb_lf_group@blacksheep.org
Onderwerp:=20 LF: Thick Litz wire needed, and more on class E PA=20 development

Is there still any of the really thick Litz wire from the old= Decca=20 stations around?   I'm after about 3 to 3.5 metres of= whatever=20 is available that is thicker than 3mm, and preferably nearer 3.5mm= =20 diameter.    Enough to make a 9.3uH coil
 
The Tank coil in the latest version of the class E PA unde= r test is=20 now the power-determining item.   At 450 Watts output the= heatsink=20 with fan is COLD - but the coil annoyingly smells of hot varnish.
It is wound with the cotton covered Litz, about 2.5mm overall= diameter=20 which itself is a big improvement over the plastic covered stuff I= was using=20 for the breadboard.  But, I have the surreal situation that as= teh coil=20 gets hot, teh wire expands, inductance falls and due to the nature= of the=20 combined Tank + L-Match circuitry causes a resulting increas= e=20 in powser output - leadign to higher dissipation and you can guess= what will=20 eventually happen if left unchecked.
 
One soluition will be to duct air from the fan through the coil= , but I'd=20 feel happier if loses were lower to start with.
 
At reduced Vdd it reaches stability running at 400 Watts withou= t getting=20 too hot and increasing itself spontaneously.
 
Efficiency, by the way, variously measures at 86 - 94%. = So I'll say=20 around 88%.    Hard to believe, but I have been= over=20 everything and double checks, and can't get teh value below 84% howe= ver=20 much I try to push errors in the worst direction.
 
The FETs are now a pair of IRFP360, and the  driver= chip had to=20 be replaced - the poor ICL7667 just went bang and split itself open= driving=20 them.  The copper of the PCB tracks running under it= became=20 discoloured so it must have bene running very hot before dying&= nbsp; Now=20 using a pair of SMT TC4420 devices - one per FET -  with additi= onal=20 copper heat dissipating fins on the PCB.    They've= survived so=20 far.
 
Its been delivering  320 Watts for an hour now off a 37V= rail, so at=20 that power level is certainly reliable; brief forays up to a 55= V rail=20 gave slightly over 700 Watts - and I could see current rising as I= watched due=20 to the coil expanding, so didn't hold it there for long, but does me= an the PA=20 as it stands could be used with AM/envelope modulation.
 
The shack is getting quite warm now !
A second chapter to the write-up will appear in due course
 
Andy
 
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