Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 275033800009C; Tue, 5 Feb 2013 05:21:06 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1U2fcI-00084V-Ld for rs_out_1@blacksheep.org; Tue, 05 Feb 2013 10:19:06 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1U2fcI-00084M-2a for rsgb_lf_group@blacksheep.org; Tue, 05 Feb 2013 10:19:06 +0000 Received: from imr-ma01.mx.aol.com ([64.12.206.39]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1U2fcF-0006YV-Id for rsgb_lf_group@blacksheep.org; Tue, 05 Feb 2013 10:19:04 +0000 Received: from mtaomg-db01.r1000.mx.aol.com (mtaomg-db01.r1000.mx.aol.com [172.29.51.199]) by imr-ma01.mx.aol.com (Outbound Mail Relay) with ESMTP id A70D4380001F9 for ; Tue, 5 Feb 2013 05:18:41 -0500 (EST) Received: from core-dfb002b.r1000.mail.aol.com (core-dfb002.r1000.mail.aol.com [172.29.54.199]) by mtaomg-db01.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 72F0DE000085 for ; Tue, 5 Feb 2013 05:18:41 -0500 (EST) References: To: rsgb_lf_group@blacksheep.org In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: Markus Vester X-MB-Message-Type: User X-Mailer: Webmail 37309-BASIC Received: from 194.138.39.56 by webmail-m154.sysops.aol.com (64.12.101.131) with HTTP (WebMailUI); Tue, 05 Feb 2013 05:18:41 -0500 Message-Id: <8CFD1A14DF77BAE-2464-89170@webmail-m154.sysops.aol.com> X-Originating-IP: [194.138.39.56] Date: Tue, 5 Feb 2013 05:18:41 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1360059521; bh=uyOP1mQw2wLuUXm6CxApsnG+5pawBXveU4icvtMI3T8=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=tVNgmTXw9Kl/IBi3S7uu1UTpv27urJgzWONbNebIGgexno87Hb6NJUpiDsOhlL/TQ alIiiRe2B7P3ydWu/43aNAdnaOJVM7LdUkizc6WKYaP9/O8Znxw51qG1qj0QfF+Krl Su9qfSzpyg90f4FsCk6s8VXsVsh15Vt9j5GaI26w= X-AOL-SCOLL-SCORE: 1:2:474310880:93952408 X-AOL-SCOLL-URL_COUNT: 2 X-Spam-Score: 1.0 (+) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Dimitrios,  in your screenshot, the duty cycle seems to be already very close to 50% but the drain voltage is alrady rising again at turn on. This might be caused by a load impedance which is lower than the design value. I think the point Eike was trying to make is that it you could intentionally reduce the duty cycle a bit to compensate for some degree of mismatch.  Best wishes, Markus (DF6NM) [...] Content analysis details: (1.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [64.12.206.39 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid 1.0 FREEMAIL_REPLY From and body contain different freemails X-Scan-Signature: 58ba09640deeac370be75328ed1b0fef Subject: Re: Re: LF: My transmit converter description Content-Type: multipart/alternative; boundary="--------MB_8CFD1A14E036293_2464_1CED6F_webmail-m154.sysops.aol.com" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_FONTCOLOR_UNKNOWN, 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: mtain-mk05.r1000.mx.aol.com ; domain : mx.aol.com DKIM : pass x-aol-sid: 3039ac1d61895110dd12721b X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ----------MB_8CFD1A14E036293_2464_1CED6F_webmail-m154.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Dimitrios, =C2=A0 in your screenshot, the duty cycle seems to be already very close to 50% bu= t the drain voltage is alrady rising again at turn on.=C2=A0This=C2=A0might= be caused by a load impedance which is lower than the design value.=C2=A0I= think the point Eike was trying to make is that it you could intentionally= reduce=C2=A0the duty cycle a bit to compensate for=C2=A0some degree of=C2= =A0mismatch. =C2=A0 Best wishes, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: Dimitrios Tsifakis <dtsifakis@gmail.com> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org> Verschickt: Di, 5 Feb 2013 10:30 am Betreff: Re: Re: LF: My transmit converter description Hi Eike,=20 =20 you are right, the drain voltage waveform is not perfect! I have since=20 corrected the duty cycle on the gate to be exactly 50%. I have also=20 added two 200 V zener diodes from the drain to the source. This will=20 clamp the voltage to 400 V which is quite safe for a 500 V FET. The=20 zener diodes together with the fuses, I think, make this design pretty=20 bullet proof.=20 =20 73, Dimitris=20 =20 PS Nothing wrong with your english :-)=20 =20 =20 2013/2/5 Eike Katzera <dl3ike@web.de>:=20 > Hi Dimitros,=20 > the pulse shape in this picture does not look good:=20 > http://people.physics.anu.edu.au/~dxt103/472/nltt/vk1sv-drain.jpg=20 > The reason seams to be the duty cycle at the gate. Please try to chang= e R5=20 > to a 100k potentiometer and trim it to a clean single Pilse an the dra= in. I=20 > solved the same problem tha way in my PA, wich killed my IRF540.=20 > Kind regards=20 > Eike DL3IKE=20 > PS: sorry for my english ;)=20 > Gesendet: Dienstag, 05. Februar 2013 um 08:45 Uhr=20 > Von: "Victor van Kooten" <V.A.G.van.Kooten@sron.nl>=20 > An: rsgb_lf_group@blacksheep.org=20 > Betreff: Re: LF: My transmit converter description=20 > Looks very nice Dimitris,hope to see/hear you soon,=20 >=20 > 73=20 >=20 > Victor=20 >=20 >>>> Dimitrios Tsifakis <dtsifakis@gmail.com> 05/02/2013 = 01:50 >>>=20 > Hello group,=20 >=20 > My transmit converter is now finished and tested - it survived two=20 > sessions of 50% duty cycle WSPR transmissions on 475 kHz and the=20 > results are great. I thought others may find this useful, so I have=20 > put a write-up on my web page:=20 >=20 > http://people.physics.anu.edu.au/~dxt103/472/nltt/=20 >=20 > It is a 50 W class-e PA designed for 50 ohm impedance, so there is no= =20 > need for an impedance transformer. Doesn't get simpler than that :-)= =20 > The driving circuit is based on G3XBM Roger's design with the=20 > difference of a 10 MHz OCXO LO and the addition of a beefy MOSFET=20 > driver.=20 >=20 > 73, Dimitris VK1SV=20 >=20 >=20 >=20 >=20 =20 ----------MB_8CFD1A14E036293_2464_1CED6F_webmail-m154.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"
Dimitrios,
 
in your sc= reenshot, the duty cycle seems to be already very close to 50% but the drai= n voltage is alrady rising again at turn on. This might be caused= by a load impedance which is lower than the design value. I think the= point Eike was trying to make is that it you could intentionally reduce&nb= sp;the duty cycle a bit to compensate for some degree of mismatch= .
 
Best wishes,
Markus (DF6NM)

-----Urspr=C3=BCngliche Mitteilung-----
Von: Dimitrios Tsifakis <dtsifakis@gmail.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 5 Feb 2013 10:30 am
Betreff: Re: Re: LF: My transmit converter description


Hi Eike, 

 

you are right, the drain voltage waveform is not perfect! I have since 

corrected the duty cycle on the gate to be exactly 50%. I have also 

added two 200 V zener diodes from the drain to the source. This will 

clamp the voltage to 400 V which is quite safe for a 500 V FET. The 

zener diodes together with the fuses, I think, make this design pretty 

bullet proof. 

 

73, Dimitris 

 

PS Nothing wrong with your english :-) 

 

 

2013/2/5 Eike Katzera <dl3ike@web.de>: 

> Hi Dimitros, 

> the pulse shape in this picture does not look good: 

> http://people.physics.anu.edu.au/~dxt103/472/nltt/v=
k1sv-drain.jpg 

> The reason seams to be the duty cycle at the gate. Please try to chang=
e R5 

> to a 100k potentiometer and trim it to a clean single Pilse an the dra=
in. I 

> solved the same problem tha way in my PA, wich killed my IRF540. 

> Kind regards 

> Eike DL3IKE 

> PS: sorry for my english ;) 

> Gesendet: Dienstag, 05. Februar 2013 um 08:45 Uhr 

> Von: "Victor van Kooten" <V.A.G.van.Kooten@sron.nl> 

> An: rsgb_lf_group@blac=
ksheep.org 

> Betreff: Re: LF: My transmit converter description 

> Looks very nice Dimitris,hope to see/hear you soon, 

> 

> 73 

> 

> Victor 

> 

>>>> Dimitrios Tsifakis <dtsifakis@gmail.com> 05/02/2013 01:50 >>> 

> Hello group, 

> 

> My transmit converter is now finished and tested - it survived two 
> sessions of 50% duty cycle WSPR transmissions on 475 kHz and the 

> results are great. I thought others may find this useful, so I have 
> put a write-up on my web page: 

> 

> http://people.physics.anu.edu.au/~dxt103/472/nltt/ 

> 

> It is a 50 W class-e PA designed for 50 ohm impedance, so there is no =


> need for an impedance transformer. Doesn't get simpler than that :-) <=
br>
> The driving circuit is based on G3XBM Roger's design with the 

> difference of a 10 MHz OCXO LO and the addition of a beefy MOSFET 

> driver. 

> 

> 73, Dimitris VK1SV 

> 

> 

> 

>


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