Return-Path: Received: from mtain-da12.r1000.mx.aol.com (mtain-da12.r1000.mx.aol.com [172.29.64.84]) by air-mc05.mail.aol.com (v129.4) with ESMTP id MAILINMC053-a9694c98f677324; Tue, 21 Sep 2010 14:16:23 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da12.r1000.mx.aol.com (Internet Inbound) with ESMTP id 64ACE380000E4; Tue, 21 Sep 2010 14:16:22 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Oy7GV-0002N3-20 for rs_out_1@blacksheep.org; Tue, 21 Sep 2010 19:08:27 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Oy7GK-0002ML-Hf for rsgb_lf_group@blacksheep.org; Tue, 21 Sep 2010 19:08:16 +0100 Received: from mail-yw0-f43.google.com ([209.85.213.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Oy7GJ-0006g1-Cf for rsgb_lf_group@blacksheep.org; Tue, 21 Sep 2010 19:08:17 +0100 Received: by ywj3 with SMTP id 3so2033939ywj.16 for ; Tue, 21 Sep 2010 11:08:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=GImZzap4YH3BQ2uclErGFnHzTPSF8jDRLfTd1ZszJl0=; b=Qa1H52rGAoRucP2zcYwoF4uvXRUAnMp0GUfsEjFFGfj0cT2ZaLDTtnxapoWqtQk6I7 BCf6xzbkSOIPUlfR9MZ9xuk1C0D8DpgMyw7ZkR6jPpFP83xEpWJMTb5wBE2qggsE38JU ehWi/w6lcx+5J31gmsjI7FZ62NV4j39XMXgRY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=MhjA255gnyICxgb5GdSF3pEa+jw6AMVoP5fw49G5kzzzn/Q/jZwnMQT4/FqUJ2hCRG XkuBlmXfC6n0SSjGZ6cmtzuPVci8iPP+9b90nCu0n3MWjklU7jdeuSg2gMJRquzmXV3G S+aiNG900W95Oxz03GvjBA9hvpRrOUEv6P17k= MIME-Version: 1.0 Received: by 10.151.114.2 with SMTP id r2mr8937479ybm.142.1285092488105; Tue, 21 Sep 2010 11:08:08 -0700 (PDT) Received: by 10.231.145.145 with HTTP; Tue, 21 Sep 2010 11:08:08 -0700 (PDT) In-Reply-To: References: Date: Tue, 21 Sep 2010 19:08:08 +0100 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: 137.5kHz WSPR beacon ON Tuesday 5.30pm -11.00pm UK time Content-Type: multipart/alternative; boundary=001517573d8441d2ef0490c8e9f6 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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-d230.1 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039ac1d40544c98f6765168 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --001517573d8441d2ef0490c8e9f6 Content-Type: text/plain; charset=ISO-8859-1 Its not possible to run from a lower voltage - unless I use a Variac on the input. A half bridge arrangement, running direct from rectified mains - so Vcc = 320V See http://www.g4jnt.com/137tx.pdf for teh original QST article. Its extremally robust - I use the soft protection system originally employed on the Decca transmitters and detailed in the write up. It can deliver 800 Watts - thats the limit I ran it to originally, so wound back to 600 Watts it will go on forever - which is more than the ATU housing could manage! Increasing the output turns ratio would do the job, but I do need an intermediate power PA, so might as well build a quickie breadboard one. All the components needed for just about any type of circuit configuration are all in the junk box. Andy www.g4jnt.com On 21 September 2010 18:47, Rik Strobbe wrote: > > Just contemplating design option for a PA for the intermediate power > range of 50 - 100 Watt > > Andy, > > running the 600W PA at 40% of the voltage should give about 100W > And the PA should be really fool proof at 1/6 th of the max. power. > > 73, Rik ON7YD - OR7T > > --001517573d8441d2ef0490c8e9f6 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Its not possible to run from a lower voltage - unless I use a Variac= on the input.=A0=A0
A half bridge arrangement, running direct from rectified mains - so= Vcc =3D 320V=A0 See http://www= .g4jnt.com/137tx.pdf=A0 for teh original QST article.
Its extremally robust=A0 - I use the soft protection system originall= y employed on the Decca transmitters and detailed in the write up.=A0=A0= It can deliver 800 Watts - thats the limit I ran it to originally, so wou= nd back to 600 Watts it will go on forever - which is more than the ATU ho= using could manage!
=A0
Increasing the output turns ratio would do the job, but I do need an= intermediate power PA, so might as well build a quickie breadboard one.= =A0=A0 All the components needed for just about any type of circuit config= uration are all=A0in the junk box.
On 21 September 2010 18:47, Rik Strobbe <Rik.Strobb= e@fys.kuleuven.be> wrote:
> Just contemplating design option=A0for a PA=A0for the intermedia= te power range of 50 - 100 Watt
=A0
Andy,
=A0<= /div>
running the= 600W PA at 40% of the voltage should give about 100W
And the PA= should be really fool proof at 1/6 th of the max. power.
=A0<= /div>
73, Rik=A0= ON7YD - OR7T
=A0<= /div>

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