Return-Path: Received: from mtain-da07.r1000.mx.aol.com (mtain-da07.r1000.mx.aol.com [172.29.64.79]) by air-dc04.mail.aol.com (v129.4) with ESMTP id MAILINDC044-86a24d3b254d3c3; Sat, 22 Jan 2011 13:43:25 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da07.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6DB4C38000127; Sat, 22 Jan 2011 13:43:24 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PgiPk-00068a-EU for rs_out_1@blacksheep.org; Sat, 22 Jan 2011 18:42:20 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PgiPj-00068R-P5 for rsgb_lf_group@blacksheep.org; Sat, 22 Jan 2011 18:42:19 +0000 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PgiPh-0008RV-5o for rsgb_lf_group@blacksheep.org; Sat, 22 Jan 2011 18:42:19 +0000 Received: by iwn2 with SMTP id 2so2893109iwn.16 for ; Sat, 22 Jan 2011 10:42:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=Ew5pbFX5+uoDNLn0hEiJ8fDgMvXo/UfAJUU9ti2ytK0=; b=uupYbQ/g1oR/pC2AgJToe0z0BcSGZLSopBOkcpsn2lSZfG2vGwMIUUJBJNyWXIXqF0 vJW2Fun5osMLJ5W6rBqjEgk9yfOVMz/iNiqqcrAo9DZ71p9+rnuU+nwpmvVo9GrwP5ux uIJBEkPQf4fxhxu2wp9smcQ4OGj7lpt17ow5M= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=f2GmSYpXHitBMwH8YH451QkSMyVnonWqwnYARjIvUey+7M98xBzI1Z1XCmMp+VnvE0 kjwqXuROYFqMXC7n1YRYhi3EQVdTPxE85fRGoWvA75rnwAAejZyX8OiSy6FxcaE1c7eH rIdtq0h232tpHdmYxC8eA6EsP0icy8TTc92bo= MIME-Version: 1.0 Received: by 10.231.36.133 with SMTP id t5mr2470455ibd.12.1295721735469; Sat, 22 Jan 2011 10:42:15 -0800 (PST) Received: by 10.231.200.211 with HTTP; Sat, 22 Jan 2011 10:42:15 -0800 (PST) In-Reply-To: References: Date: Sat, 22 Jan 2011 18:42:15 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: RE: Thick Litz wire needed, and more on class E PA development Content-Type: multipart/alternative; boundary=00221540147ec53afd049a73b932 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 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m022.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d404f4d3b254c2ed1 X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) --00221540147ec53afd049a73b932 Content-Type: text/plain; charset=ISO-8859-1 That inductance value is not all allocated to the tank. About 5uH is the tank. Then follows an L-match network of series L shunt C to transform 50 ohms to the design Rload of 2.8 ohms. Both L elements then get absorbed into one. I've discovered one or two advantages in this technique - that make tuning up both easier in some respects and more critical in others. But it does work very well *provided* L remains constant. Reducing L on its own using this configuration increases current / power output quickly - although , very interestingly, efficiency hardly shifts. I also think there may be 'issues' if the output impedance developds a significant indicucive term - that's a subject for final investigation -how it copes with all phases of mismatch. And after writing the previous eamil - realised there is a quick solution - just make the coil from two or three parallel strands of the same Litz Andy www.g4jnt.com On 22 January 2011 18:31, Rik Strobbe wrote: > 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@blacksheep.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 > development > > 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 available > 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 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 > 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 resulting *increase* in powser > output - leadign to higher dissipation and you can 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 getting > 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 driving them. The > copper of the PCB tracks running under it became discoloured so it must have > bene running very hot before dying Now using a pair of SMT TC4420 devices - > one per FET - with additional copper heat 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 watched 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 modulation. > > The shack is getting quite warm now ! > A second chapter to the write-up will appear in due course > > Andy > www.g4jnt.com > > --00221540147ec53afd049a73b932 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
That inductance=A0value=A0is not all allocated to the tank.=A0=A0 Abo= ut 5uH is the tank.=A0 Then follows an L-match network of series L shunt= C to transform 50 ohms to the design Rload of 2.8 ohms.=A0=A0 Both L elem= ents then get absorbed into one.=A0=A0=A0 I've discovered one or two= advantages in this technique - that make tuning up both easier in some re= spects and more critical in others.=A0 But it does work very well=A0provided =A0L=A0 remains constant.=A0=A0=A0=A0 Reducing L on it= s own using this configuration increases current / power output quickly -= although , very interestingly, efficiency hardly shifts.=A0=A0
=A0
I=A0also think there may be 'issues' if the output impedance= developds a significant indicucive term - that's a subject for final= investigation -how it copes with all phases of mismatch.
=A0
And after writing the previous eamil - realised there is a quick solu= tion - just make the coil from two or three parallel strands of the same= Litz
=A0
Andy
=A0


=A0
On 22 January 2011 18:31, Rik Strobbe <Rik.Strobbe@fy= s.kuleuven.be> wrote:
Hello Andy,
=A0
with 9.3UH=A0the class E amp=A0must= have a rather high Q (12 ?). Maybe a lower Q (and=A0more or less proporti= onal=A0lower L) might help ?
=A0
73, Rik=A0 ON7YD - OR7T
=A0
Van: owner-rsgb_lf= _group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens An= dy Talbot [andy.= g4jnt@gmail.com]
Verzonden: zaterdag 22 januari 2011 18:14
Aan: rsgb_lf_group@blac= ksheep.org
Onderwerp: LF: Thick Litz wire needed, and more= on class E PA development

Is there still any of the really thick Litz wire from the old Decca= stations around?=A0=A0 I'm after about=A03 to 3.5 metres of whatever= is available that is thicker than 3mm, and preferably nearer 3.5mm diamet= er.=A0=A0=A0 Enough to make a 9.3uH coil
=A0
The Tank coil in=A0the latest version of the class E PA under test is= now the power-determining item.=A0=A0 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 diamete= r which itself is a big improvement over the plastic covered stuff I was= using for the breadboard.=A0 But, I have the surreal situation that as te= h coil gets hot, teh wire expands, inductance falls and due to the nature= of the combined Tank + L-Match circuitry causes a resulting incre= ase in powser output - leadign to higher dissipation and you can= guess what will eventually happen if left unchecked.
=A0
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.
=A0
At reduced Vdd it reaches stability running at 400 Watts without gett= ing too hot and increasing itself spontaneously.
=A0
Efficiency, by the way, variously measures at 86 - 94%.=A0 So I'l= l say around 88%.=A0=A0=A0 Hard to believe, but=A0I have been over everyth= ing and double checks, and can't get teh value below 84% however much= =A0I try to push errors in the worst direction.
=A0
The=A0FETs are now a pair of IRFP360, and the =A0driver chip had to= be replaced - the poor ICL7667 just went bang and split itself open drivi= ng them.=A0=A0The copper of the PCB tracks running under=A0it became disco= loured so=A0it must have bene running very hot before dying=A0 Now using= a pair of SMT TC4420 devices - one per FET - =A0with additional copper he= at dissipating fins on the PCB.=A0=A0=A0 They've survived so far.
=A0
Its been delivering=A0 320 Watts for an hour now off a 37V rail, so= at that power level is certainly reliable;=A0brief forays up to a 55V rai= l gave slightly over 700 Watts - and I could see current rising as I watch= ed due to the coil expanding, so didn't hold it there for long, but do= es mean the PA as it stands could be used with AM/envelope modulation.
=A0
The shack is getting quite warm now !
A second chapter to the write-up will appear in due course
=A0
Andy
=A0

--00221540147ec53afd049a73b932--