Return-Path: Received: from mtain-mg07.r1000.mx.aol.com (mtain-mg07.r1000.mx.aol.com [172.29.96.207]) by air-di08.mail.aol.com (v127_r1.1) with ESMTP id MAILINDI083-eb684b7af6eb176; Tue, 16 Feb 2010 14:50:03 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mg07.r1000.mx.aol.com (Internet Inbound) with ESMTP id 65685380002F0; Tue, 16 Feb 2010 14:50:01 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NhTPj-00068O-44 for rs_out_1@blacksheep.org; Tue, 16 Feb 2010 19:48:55 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NhTPi-00068F-9J for rsgb_lf_group@blacksheep.org; Tue, 16 Feb 2010 19:48:54 +0000 Received: from mail-bw0-f214.google.com ([209.85.218.214]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NhTPf-0003l9-Gj for rsgb_lf_group@blacksheep.org; Tue, 16 Feb 2010 19:48:54 +0000 Received: by bwz6 with SMTP id 6so3542393bwz.31 for ; Tue, 16 Feb 2010 11:48:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=210kgoSiu6DGBF1AjPOlwBWHKCzbUmKYgneF+ibVZjE=; b=issc5WsWYh7KmTkn79kJrY+VRo4eBtmyDkJ5EnnVsdZBlUJel7ynxseOh4focSQk7I UNkbyK6Fy6WpAZ20PrelmYueHafspNnLirJwBvp9hg56yd14YTGv2AuRuVyl4seUGeim S4y2xW6YIwaedwnMyKh4sslL1o5C842S9jViA= 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=AZ24ZN+6q14FFX4HNutjjsdU11kQhiXsa0CAaplKw09pmuSlGHfZmHRWgiU7QOQ+Tv 265iJnVKYyl2QrUkN6zzyC9S0ALinzvssLnLLI48jSCUQCgIz6fcbVM7SERk78rIyho8 GqCBp9NYySzW5ZOYMEUhbFBsUdMOKrWf8kBWc= MIME-Version: 1.0 Received: by 10.204.135.153 with SMTP id n25mr743749bkt.156.1266349722839; Tue, 16 Feb 2010 11:48:42 -0800 (PST) In-Reply-To: <006501caaf3b$53ddb350$0201a8c0@Clemens04> References: <006501caaf3b$53ddb350$0201a8c0@Clemens04> Date: Tue, 16 Feb 2010 19:48:42 +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: PA matching oddity Content-Type: multipart/alternative; boundary=0015174c192c642c92047fbd054f 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-d260.1 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039ac1d60cf4b7af6e901ff X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015174c192c642c92047fbd054f Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable A follow up to this sage After much puzzling over the design, and comment here about how it must be 3:1 teh only solution was to measure it. So I connected up and measured voltages. Indeed, it does turn out to be 3:1 - So how could it deliver 1kW plus... Next, fitted the module to a big heatsink, got out the 'telephone exchang= e' PSU (50V 25 A) and wound up the amp to the max it would give. Unfortunately the PSU current limited when supplying only 800 or so watts, but by winding teh PSU down to 44V, it current limited at a higher value= and I got 950 Watts before the PSU gave up (off 44V). So it really was givi= ng more power out than it 'ought to' BUT, as Clemens mentioned I'd ignored the saturation element and in fact,= if used as a switching amp can give well over 1kW. I'd used this aspect in the 700W 137kHz Tx, http://www.g4jnt.com/137tx.pdf and forgot it. Enoug= h said. Anyway, tested the PA, and found it would go down to about 5MHz where the transformers began to give up, and up to about 20MHz where the FETs lost gain / efficiency. So as a 13.56MHz industrial unit its fine, but of little use as a general HF amp. BUT, with suitable change of output transformer, could probably be persuaded to give 1.5kW on 137 or 500kHz -= if a suitable PSU were to hand. That's where it sits now. Experimentation done, and any further work can wait for other projects to get pushed of ft= he stack. Andy www.g4jnt.com On 16 February 2010 19:07, Clemens Paul wrote: > Andy,Rik, > > after thinking a while over the transformer of Andy's PA and referring= to > http://www.g4jnt.com/pamatch.gif > I'm sorry to say that > I'm still quite (say 99,9%) sure that it is a conventional 1:9 (Z) > transfomer. > > Here are some crucial points which exclude *absolutely* the above design > to be an autotransformer,(1:16 or whatever). > 1.) Autotransformers provide no dc isolation, i.e. you have a dc path fr= om > the primary to secondary side. > *There is no such dc path here.* > 2.)In a bootstrap design the *braid* of one coax end is *connected *to= the > *center* > *conductor* at the start of the same coax (1:4) or of the next coax > section (1:9 or higher). > This is not the case in this design.*The center of the secondary is > nowhere connected* > *with a braid.* > ** > BTW there is no reason to worry about the theoretical 900W limit in line= ar > mode. > If the PA is slightly overdriven you get easily one 1dB more power on th= e > fundamental > frequency which is about 1133W so you have enough margin for losses of= the > low pass filter > losses etc. > It's very unlikely that this PA which was used as industrial RF heater > was designed to be superlinear. > > 73 > Clemens > DL4RAJ > > ** > > > > ----- Original Message ----- > *From:* Andy Talbot > *To:* rsgb_lf_group@blacksheep.org > *Cc:* ukmicrowaves@yahoogroups.com > *Sent:* Tuesday, February 09, 2010 10:43 PM > *Subject:* Re: LF: RE: PA matching oddity > > BINGO - Tnx Rik, thats it, convincing. Sorted > > So my thing IS 1:4 turns ratio, (1:16 Z ratio) just as the calculation= s > said it needed to be, and is indeed, effectively, an auto transformer. > Otherwise known as a bootstrapped coaxial transformer, but just configur= ed > with different reference points to confuse everyone. Your second referen= ce, > the Semelab paper, (UKuW see below) gives the answer. > > Look at page 10, the 1:9 Ruthroff UnUn . With just two bits of coa= x, > which are then bootstrapped up on top of the input to give a 3:1 ratio= (for > 1:9 impedance). Add another turn, so three windings are bootstrapped= on > top of the primary, rearrange the grounding points and there, in all its > glory, is my mystery. > > The reference / grounding points can be shifted as the mosfet PA has = two > separate, non magnetically linked cores. This is is just normal push-pu= ll > HF PA practice, and being so normal in its concept, completely hides hid= es a > big real advantage - it enables the designer to float just whatever > ternainals need to be floated for balanced / unbalanced operation, and= even > to provide DC isolation, Any conductor passing through the core allows= one > end to be completely Rf decoupled from the other end, so that's how bala= nced > operation is permitted with the basic Ruthrof design shown in the paper. > > On the same page, a single length of coax is shown giving 1:2 > transformation by the same bootstrapping arrangement, and when the > transmision line is shown as a twisted pair rather than coax, then wrapp= ed > on a torroid, it becomes the 1:4 balun beloved of HF antenna constructor= s. > A natural progression that helps illustrate the concept of a loop of= coax > giving one turn more than it appears to. > > It all falls out. > ... life is worth living again ... > ... can retire happy ... > > > Andy > www.g4jnt.com > ... now, next job, how to sort out the world financial crisis ... > > On 9 February 2010 19:53, Rik Strobbe wrot= e: > >> Andy, >> >> have a look here : >> >> http://www.polyfet.com/HFE0503_Leong.pdf >> >> http://www.semelab.com/rf/documents/Push-Pull%20Circuits%20and%20Wideba= nd%20Transformers.pdf >> >> 73, Rik ON7YD - OR7T >> >> ------------------------------ >> *Van:* owner-rsgb_lf_group@blacksheep.org [ >> owner-rsgb_lf_group@blacksheep.org] namens Andy Talbot [ >> andy.g4jnt@googlemail.com] >> *Verzonden:* dinsdag 9 februari 2010 18:10 >> *Aan:* rsgb_lf_group@blacksheep.org; ukmicrowaves@yahoogroups.com >> *Onderwerp:* LF: PA matching oddity >> >> >> > ------------------------------ > > > Eingehende eMail ist virenfrei. > Von AVG =FCberpr=FCft - www.avg.de > Version: 9.0.733 / Virendatenbank: 271.1.1/2677 - Ausgabedatum: 02/09/10 > 08:35:00 > > --0015174c192c642c92047fbd054f Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
A follow up to this sage=A0=A0
=A0
After much puzzling over the design, and comment here about how it mu= st be 3:1 teh only solution was to measure it.=A0=A0So I connected up and= measured voltages.=A0Indeed, it does turn out to be 3:1 -=A0=A0 So=A0=A0= how could it deliver 1kW plus...
=A0
Next, fitted the module to a big heatsink, =A0got out the 'teleph= one exchange' PSU (50V 25 A) and wound up the amp to the max it would= give.=A0=A0 Unfortunately the PSU current limited when supplying only 800= or so watts, but by winding teh PSU down to 44V, it current limited at a= higher value and I got=A0950 Watts before the PSU gave up (off 44V).=A0= =A0=A0 So it really was giving more power out than it 'ought to'
=A0
BUT, as Clemens mentioned I'd ignored the saturation element and= in fact, if used as a switching amp can give well over 1kW.=A0=A0 I'd= used this aspect in the 700W 137kHz Tx, http://www.g4jnt.com/137tx.pdf=A0 and forgot it.=A0=A0 Enoug= h said.
=A0
Anyway, tested the PA, and found=A0it would go down to about 5MHz whe= re the transformers began to give up, and up to about 20MHz where the FETs= lost gain / efficiency.=A0=A0 So as a 13.56MHz industrial unit its fine,= but of little use as a general HF amp.=A0=A0 BUT, with suitable change of= output transformer, could probably be persuaded to give 1.5kW on 137 or= 500kHz - if a suitable PSU were to hand.=A0 That's where it sits now.= =A0=A0 Experimentation done, and any further work can wait for other proje= cts to get pushed of fthe stack.
On 16 February 2010 19:07, Clemens Paul <cpaul@gmx.net> wrote:
Andy,Rik,
=A0
after thinking a while over the trans= former of Andy's PA and referri= ng to
I'm sorry to say that
I'm still quite (say 99,9%)=A0sur= e that it is=A0a conventional 1:9 (Z) transfomer.
=A0
Here are some crucial points which=A0= exclude *absolutely* the above design
to be an autotransformer,(1:16 or whatever).
1.) Autotransformers=A0provide no dc= isolation, i.e. you have a dc path from
the primary to secondary side.=
There is no such dc path here= .
2.)In a bootstrap design the = braid of=A0one coax end is connected to the center
conductor at the sta= rt of the same=A0 coax (1:4) or of the next=A0 coax section (1:9 or higher= ).
This is not the case in this design.<= strong>The center of the secondary is nowhere connected
with a braid.=
=A0
BTW there is no reason to worry about= the theoretical 900W limit in linear mode.
If the PA is slightly overdriven you= get easily=A0one 1dB more power on the fundamental
frequency which is about 1133W so you= have enough margin for losses of the low pass filter
losses etc.
It's very unlikely that this PA= which was used as industrial RF= heater
was designed to be superlinear.
=A0
73
Clemens
DL4RAJ
=A0
=A0
=A0
=A0
----- Original Message -----
Sent: Tuesday, February 09, 2010 10= :43 PM
Subject: Re: LF: RE: PA matching od= dity

BINGO -=A0 Tnx Rik, thats=A0it, convincing.=A0=A0Sorted
=A0
So my thing=A0=A0IS 1:4 turns ratio, (1:16 Z ratio) =A0just as the=A0= calculations said it needed to be,=A0and is indeed, effectively, an auto= transformer.=A0 Otherwise known as a bootstrapped coaxial transformer, bu= t just configured with different reference points=A0to confuse everyone.= =A0Your=A0second reference, the Semelab paper, (UKuW see below) =A0gives= the answer.=A0=A0
=A0
Look at=A0page 10,=A0=A0=A0the 1:9 Ruthroff=A0=A0 UnUn .=A0=A0=A0With= just=A0two bits of coax, which are then bootstrapped up on top of the inp= ut to give a 3:1 ratio (for 1:9 impedance).=A0=A0 Add another turn, so thr= ee windings are=A0 bootstrapped on top of the primary, rearrange the groun= ding points and there, in all its glory, is my mystery.=A0=A0=A0
=A0
The reference / grounding points can be shifted as the mosfet PA=A0= =A0has=A0 two separate, non magnetically linked=A0cores.=A0 This is is jus= t=A0normal push-pull HF PA practice, and being so=A0normal in its concept,= completely hides hides=A0a big=A0real advantage - it enables the designer= to float just whatever ternainals need to be floated for balanced / unbal= anced operation, and even to provide DC isolation,=A0=A0 Any conductor pas= sing through the core allows one end to be completely Rf=A0decoupled from= the other end, so that's how balanced operation is permitted with the= basic Ruthrof design shown in the paper.
=A0
On the same page,=A0a single length of coax is shown giving 1:2 trans= formation by the same bootstrapping arrangement, and when the transmision= line is shown as a twisted pair rather than coax, then wrapped on a torro= id, it=A0becomes the 1:4 balun beloved of=A0HF antenna=A0constructors.=A0= =A0 A natural progression that helps illustrate the concept=A0 of=A0 a loo= p of coax giving one turn more than it appears to.
=A0
It all falls out.=A0
... life is worth living again ...
... can retire happy ...
=A0
... now, next job, how to sort out the world financial crisis ...
On 9 February 2010 19:53, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:
Andy,<= /font>
=A0
have a look here :
=A0
=A0
73, Rik=A0 ON7YD - OR7T<= /font>
=A0
Van: owner-rsgb_lf_group@blacksheep.= org [owner-rsgb_lf_group@blacksheep.org] namens Andy Talbot [andy.g4jnt@googlem= ail.com]
Verzonden: dinsdag 9 februari 2010 18:10
Aan: rsgb_lf_group@black= sheep.org; ukmicrowaves@yahoogroups.com
Onderwerp: LF: PA matching oddity

=A0


Eingehende eMail ist virenfrei.
Von AVG =FCberpr=FCft - www.avg.de
Version:= 9.0.733 / Virendatenbank: 271.1.1/2677 - Ausgabedatum: 02/09/10 08:35:00=


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