Return-Path: Received: from mtain-mk05.r1000.mx.aol.com (mtain-mk05.r1000.mx.aol.com [172.29.97.137]) by air-de08.mail.aol.com (v129.4) with ESMTP id MAILINDE083-5ec04d35f0b02a3; Tue, 18 Jan 2011 14:57:36 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8D69038000098; Tue, 18 Jan 2011 14:57:33 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PfHf1-0004h9-Kp for rs_out_1@blacksheep.org; Tue, 18 Jan 2011 19:56:11 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PfHf1-0004h0-2k for rsgb_lf_group@blacksheep.org; Tue, 18 Jan 2011 19:56:11 +0000 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PfHey-0005rw-J8 for rsgb_lf_group@blacksheep.org; Tue, 18 Jan 2011 19:56:11 +0000 Received: by iwn2 with SMTP id 2so12882iwn.16 for ; Tue, 18 Jan 2011 11:56:06 -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=Taggv/w2opH+9gJqtLTvC3mKXFgbPs0be09wPjodUcA=; b=xGBiIIKfDwL28vThwaihiWqu423MtaU7zX2zPlz/Qoi331etH7bJHb0oqsHPH1xhVd eY175MiYuuEvQD8hEsyI06fYblfQCXyxOixgEmTL/dkFFRZ+305Yxppkr2+Z3E6TiVfo /EzkRsV25lmdqYn7kieqRriYTg/y7Yz3cfzIA= 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=ZTcbuM8AMZw7Tq2IUOL8at9aZPpXexLmS25qMN2ltE+Yc2pj8LE2cROqA+M2hWAbkD SIJ/Mf3Us3fhSzFvw31CzqhRDtPBMpzP4HNw31/8OpT0IuuwW4BtMV1fYuHsulZhh01f AUC5G8L/ri0dUG5ZAqX2nnrZs+Zfi8qtt5wN0= MIME-Version: 1.0 Received: by 10.231.207.84 with SMTP id fx20mr6506496ibb.62.1295380566308; Tue, 18 Jan 2011 11:56:06 -0800 (PST) Received: by 10.231.200.211 with HTTP; Tue, 18 Jan 2011 11:56:06 -0800 (PST) In-Reply-To: <4D2F7C5F.9090103@iup.uni-heidelberg.de> References: <003801cbb33e$8b59e620$0401a8c0@xphd97xgq27nyf> <4929CA3383DD45FCBC44A80A2733B139@PcMinto> <004801cbb34a$5b8ab580$0401a8c0@xphd97xgq27nyf> <4D2F736C.6010001@iup.uni-heidelberg.de> <78E135BF916345EE933DF6E8F3FB81D4@PcMinto> <4D2F7C5F.9090103@iup.uni-heidelberg.de> Date: Tue, 18 Jan 2011 19:56:06 +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: FET RDS Content-Type: multipart/alternative; boundary=90e6ba4fc51480f94d049a244a33 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m007.2 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d61894d35f0ad769f X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) --90e6ba4fc51480f94d049a244a33 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable An interesting circuit, but there is one thing that puzzles me. There is= a lot of open loop gain as well as non-linear discontinuity in the drive tha= t would contribute audio distortion. Just like crossover distortion in a class B audio stage It could be completely solved by adding negative feedback into the audio path from the output - same as any Hi-Fi amp - but I don't seen any. Is= it elsewhere and just doesn't appear on that schmatic? For general EER type modulation techniqes, a phase/amplitude generator module would be useful, giving Pythagoras and arctan outputs from baseban= d audio in. A ideal task for a DSPic Andy www.g4jnt.com 2011/1/13 Stefan Sch=E4fer > Hi Minto, > > Am 13.01.2011 23:09, schrieb Minto Witteveen: > > Stefan, >> >> You mentioned the IXDD414 in a previous message here on the reflector,= and >> I immediately downloaded the datasheet. The IXDD414 certainly looks ver= y >> promising and I plan to experiment with it as soon as we are allowed ba= ck on >> 500.... >> > I've used them successfully up to 10 MHz, driving about 2 nF. > > Now if I can just find a supplier here in PA who stocks this chip. >> > Yes, that's the problem. I've got 5 of them as a sample part but later= i > needed more. So i've ordered at digikey in USA. If you find a cheeper > distributor, please tell me (quantity below 10000000000000) :-) > > My original 500 KHz design was for linear operation (so I could use psk3= 1) >> but I only made one qso in PSK, the rest in ordinary CW. A new design= can >> and will be much simpler. >> > Have you heared about a class H modulator? This is a circuit that separa= tes > AM and FM. The FM and PA can be done by a class E design and the AM is > applied by modulating the supply voltage by a step down converter (the= class > H modulator). I've never built one but there are some interesting exampl= es > at http://www.classeradio.com/classh.htm > This would be a good combination to push-up a class E PA for linear mode= . > Since i do nothing more than CW/QRSS/DFCW i actually do not need one ;-) > > 73, Stefan/DK7FC > > >> Thanks for the info. >> >> Regards, >> Minto pa3bca >> >> >> -------------------------------------------------- >> From: "Stefan Sch=E4fer" >> Sent: Thursday, January 13, 2011 22:49 >> To: >> Subject: Re: LF: FET RDS >> >> Minto, >>> >>> 14 nF gate capacity can easily be driven by a IXDD414, at 500 kHz and >>> even at 1800 kHz. I've built a 600W class E for 160m running at 36 VDC= (for >>> /p, 3 car batteries in series ;-) ), using 4xIRFP260N. Efficiency is= above >>> 90% but mostly due to losses in the coils ( i like to built it compact= :-) >>> ). >>> >>> 73, Stefan/DK7FC >>> >>> >> >> > --90e6ba4fc51480f94d049a244a33 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
An interesting circuit, but there is one thing that puzzles me.=A0 Th= ere is a lot of open loop gain as well as=A0non-linear discontinuity in th= e drive that would contribute audio distortion.=A0=A0 Just like crossover= distortion in a class B audio stage=A0=A0
=A0
It could be completely solved by adding negative feedback into the au= dio path from the output - same as any Hi-Fi amp -=A0but I don't seen= any.=A0=A0 Is it elsewhere and just doesn't appear on that schmatic?<= /div>
=A0
For general EER type modulation techniqes, a phase/amplitude generato= r module would be useful,=A0giving =A0Pythagoras and arctan outputs from= baseband audio in.=A0=A0 A ideal=A0task for a DSPic
=A0
Andy


=A0
2011/1/13 Stefan Sch=E4fer &l= t;schaefer@iup.uni-heide= lberg.de>
Hi Minto,

Am 13.01.2011= 23:09, schrieb Minto Witteveen:=20

Stefan,

You mentioned= the IXDD414 in a previous message here on the reflector, and I immediatel= y downloaded the datasheet. The IXDD414 certainly looks very promising and= I plan to experiment with it as soon as we are allowed back on 500....
I've used them successfully up to 10 MHz, driving= about 2 nF.=20

Now if I can just find a suppl= ier here in PA who stocks this chip.
Yes, that's= the problem. I've got 5 of them as a sample part but later i needed= more. So i've ordered at digikey in USA. If you find a cheeper distri= butor, please tell me (quantity below 10000000000000) :-)=20

My original 500 KHz design was= for linear operation (so I could use psk31) but I only made one qso in PS= K, the rest in ordinary CW. A new design can and will be much simpler.
Have you heared about a class H modulator? This is a ci= rcuit that separates AM and FM. The FM and PA can be done by a class E des= ign and the AM is applied by modulating the supply voltage by a step down= converter (the class H modulator). I've never built one but there are= some interesting examples at http://www.classeradio.com/classh.htm
This would be a good combination to push-up a class E PA for linear mode.= Since i do nothing more than CW/QRSS/DFCW i actually do not need one ;-)<= br>
73, Stefan/DK7FC=20

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