Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=3 Fuz1=3 Fuz2=3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v54HlwxK022699 for ; Sun, 4 Jun 2017 19:47:59 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dHZVU-0007Bk-Re for rs_out_1@blacksheep.org; Sun, 04 Jun 2017 18:40:04 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dHZVU-0007Bb-Bd for rsgb_lf_group@blacksheep.org; Sun, 04 Jun 2017 18:40:04 +0100 Received: from smtp3web.tin.it ([212.216.176.237]) by relay1.thorcom.net with esmtp (Exim 4.89) (envelope-from ) id 1dHZVQ-0000YC-9j for rsgb_lf_group@blacksheep.org; Sun, 04 Jun 2017 18:40:03 +0100 Received: from feu4 (10.192.64.14) by smtp3web.tin.it (8.6.060.43) id 583FEE8C03265D23; Sun, 4 Jun 2017 19:39:58 +0200 Received: from (80.182.160.35) by wmlighttin.pc.tim.it; Sun, 4 Jun 2017 19:39:58 +0200 Message-ID: <15c74312b98.marcocadeddu@tin.it> Date: Sun, 4 Jun 2017 19:39:58 +0200 (CEST) From: "marcocadeddu@tin.it" To: Mime-Version: 1.0 X-Originating-IP: 80.182.160.35 X-Scan-Signature: 7c7a1907d3a7d57b28660e5fb4c32107 Subject: R: Re: Re: R: Re: LF: Re: I: Fw: For today the FETs survived... Content-Type: text/plain;charset="UTF-8" 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-Scanned-By: MIMEDefang 2.75 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by lipkowski.org id v54HlwxK022699 Status: O X-Status: X-Keywords: X-UID: 11888 Thank you Andy :-) now by the first I have to find a way to fix the coil (which is quite bulky..) I used 2 corks :-)) and hotmelt glue, but after 1 hour of testing the coil falled :-((( looking on the notes, the first tank coil had 92T and the link had 25T with this combination the voltage across the link coupling was about Vpp = Vdc but in this conditions, this afternoon when testing at 50Vdc without the guard circuit I had Idd 0,87A and Wout 29,5 connecting the guard Idd dropped to 0,41A and Wout to 13,2W while Ig=0,16A. On the other hand with 25 ohm load, Idd was 0,31A and Wout 8,4W with Ig 0,26A. So let me borrow another cork :-))) Thank you again for support CU Marco IK1HSS ----Messaggio originale---- Da: andy.g4jnt@gmail.com Data: 4-giu-2017 18.42 A: Ogg: Re: Re: R: Re: LF: Re: I: Fw: For today the FETs survived... Yes. You need to adjust the link so current is driven back into the supply when RF amps exceed the maximum that you have designed for. Up to that point there should be no guard current as the induced voltage in the link, when rectified , is less than the supply. If the link coupling were to be perfect, ie it behaved as a transformer, then at full power into your designed load the voltage across the tank coil would be Q * Vdc * 4/pi * SQRT(2) (since you calculated Rload this way). The SQRT terms comes from the DC being the peak So the turns ratio (for perfect coupling) if made equal equal to 1 : Q * 4 / pi * SQRT(2) ,will start to generate load current just as maximum output is reached. But things aren't perfect; the mutual coupling is never 1 in an air wound coil (mine is about 0.6), the rectification doesn't give exactly peak volts, so you have to experiment, changing the link turns until you get the limiting you want. Fortunately it scales with DC volts, so guard circuit testing can be done at low supply / power out. 'jnt On 4 June 2017 at 16:47, marcocadeddu@tin.it wrote: > heyheyhey.. > now I'm testing with the new coil still at 50Vdc ;-) > ops I was forgetting: without dissipator :-)) just with the mounting > alu block it runs at room temp, maybe it is worth later at full power! > The > picture of Andy is not in thema: is the consequence of qro ampli on > undersize external loading coil :-) > By the way when this ampli will finally run on the antenna I need to re- > size the variometer because it warms already with 250W.. > > Also the new tank coil with 2,5mm² wire after 1 hour has a bit of > fever.. but is not warm as the former. > > Just a quick question Andy: speaking of the guard circuit, if I read > Iguard whithout mismatch is correct the assumption that the link has > too many turns? > > Alan: I'm vintage.. and I'm sure I have a variac in the basement :-) > thanks for the hint ;-) > > Thanks all for the psycological and praxi help !! > Marco > > ----Messaggio originale---- > Da: andy.g4jnt@gmail.com > Data: 4-giu-2017 17.49 > A: > Ogg: Re: R: Re: LF: Re: I: Fw: For today the FETs survived... > > Something like this ... > http://www.g4jnt.com/QRO_LF_DoesThis.JPG> 'jnt :-) > > > On 4 June 2017 at 16:25, Chris Wilson wrote: > > > Hello Alan, > > > > > > No, what he needs is a video camera, and the courage to post the > > result here for scrutiny, we need a bit of fun now and again ;) > > > > Good luck Marco, what's the worst that can happen.... :) > > > > > > > > >