Return-Path: Received: from imd-da09.r1000.mx.aol.com (imd-da09.r1000.mx.aol.com [172.29.11.13]) by air-da05.mail.aol.com (v127_r1.1) with ESMTP id MAILINDA052-86154b7bc588133; Wed, 17 Feb 2010 05:31:36 -0500 Received: from mtain-da06.r1000.mx.aol.com (mtain-da06.r1000.mx.aol.com [172.29.64.78]) by imd-da09.r1000.mx.aol.com (Inbound Mail Deferral) with ESMTP id 8C8497001CE74; Wed, 17 Feb 2010 05:31:36 -0500 (EST) Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-da06.r1000.mx.aol.com (Internet Inbound) with ESMTP id ED12538000401; Wed, 17 Feb 2010 05:31:33 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NhhAZ-0007J4-Gj for rs_out_1@blacksheep.org; Wed, 17 Feb 2010 10:30:11 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NhhAY-0007Iv-N3 for rsgb_lf_group@blacksheep.org; Wed, 17 Feb 2010 10:30:10 +0000 Received: from mail.gmx.net ([213.165.64.20]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1NhhAW-0007SB-5R for rsgb_lf_group@blacksheep.org; Wed, 17 Feb 2010 10:30:10 +0000 Received: (qmail invoked by alias); 17 Feb 2010 10:30:00 -0000 Received: from p5DD3484B.dip.t-dialin.net (EHLO Clemens04) [93.211.72.75] by mail.gmx.net (mp015) with SMTP; 17 Feb 2010 11:30:00 +0100 X-Authenticated: #17214767 X-Provags-ID: V01U2FsdGVkX1/XKlZrJ+3XLkU047YqspkpaG2wXxA0J7jbyijSOE r13ZDxQvzgB47q Message-ID: <006601caafbc$28de4c10$0201a8c0@Clemens04> From: "Clemens Paul" To: References: <006501caaf3b$53ddb350$0201a8c0@Clemens04> Date: Wed, 17 Feb 2010 11:29:55 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3598 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3350 X-Y-GMX-Trusted: 0 X-FuHaFi: 0.46000000000000002,0.46000000000000002 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="----=_NextPart_000_0062_01CAAFC4.877764C0" 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-sid: 3039ac1d404e4b7bc5855c86 X-AOL-IP: 193.82.116.20 ------=_NextPart_000_0062_01CAAFC4.877764C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable >and I got 950 Watts before the PSU gave up (off 44V). > So it really was giving more power out than it 'ought to' Uncertainty of a bird wattmeter with a 1kW slug would be around +/-50W= , with a 2,5kW element +/-125W. Power master is a bit better with +/- 30W. 73 Clemens DL4RAJ ----- Original Message -----=20 From: Andy Talbot To: rsgb_lf_group@blacksheep.org Sent: Tuesday, February 16, 2010 8:48 PM Subject: Re: LF: RE: PA matching oddity A follow up to this sage After much puzzling over the design, and comment here about how it= must be 3:1 teh only=20 solution was to measure it. So I connected up and measured voltages.= Indeed, it does turn out=20 to be 3:1 - So how could it deliver 1kW plus... Next, fitted the module to a big heatsink, got out the 'telephone= exchange' PSU (50V 25 A)=20 and wound up the amp to the max it would give. Unfortunately the PSU= current limited when=20 supplying only 800 or so watts, but by winding teh PSU down to 44V, it= current limited at a=20 higher value and I got 950 Watts before the PSU gave up (off 44V). = So it really was giving=20 more power out than it 'ought to' BUT, as Clemens mentioned I'd ignored the saturation element and in= fact, if used as a=20 switching amp can give well over 1kW. I'd used this aspect in the 70= 0W 137kHz Tx,=20 http://www.g4jnt.com/137tx.pdf and forgot it. Enough said. Anyway, tested the PA, and found it would go down to about 5MHz wher= e the transformers began=20 to give up, and up to about 20MHz where the FETs lost gain / efficienc= y. So as a 13.56MHz=20 industrial unit its fine, but of little use as a general HF amp. BUT= , with suitable change of=20 output transformer, could probably be persuaded to give 1.5kW on 137= or 500kHz - if a suitable=20 PSU were to hand. That's where it sits now. Experimentation done,= and any further work can=20 wait for other projects to get pushed of fthe 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 refer= ring 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 from 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 coa= x 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 linear mode. If the PA is slightly overdriven you get easily one 1dB more power= on the fundamental frequency which is about 1133W so you have enough margin for losse= s of the low pass filter losses etc. It's very unlikely that this PA which was used as industrial RF he= ater was designed to be superlinear. 73 Clemens DL4RAJ ----- Original Message -----=20 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 cal= culations said it needed=20 to be, and is indeed, effectively, an auto transformer. Otherwise kno= wn as a bootstrapped=20 coaxial transformer, but just configured with different reference poin= ts to confuse everyone.=20 Your second reference, the Semelab paper, (UKuW see below) gives the= answer. Look at page 10, the 1:9 Ruthroff UnUn . With just two bit= s of coax, which are then=20 bootstrapped up on top of the input to give a 3:1 ratio (for 1:9 imped= ance). Add another turn,=20 so three windings are bootstrapped on top of the primary, rearrange= the grounding points and=20 there, in all its glory, is my mystery. The reference / grounding points can be shifted as the mosfet PA= has two separate, non=20 magnetically linked cores. This is is just normal push-pull HF PA pra= ctice, and being so normal=20 in its concept, completely hides hides a big real advantage - it enabl= es the designer to float=20 just whatever ternainals need to be floated for balanced / unbalanced= operation, and even to=20 provide DC isolation, Any conductor passing through the core allows= one end to be completely=20 Rf decoupled from the other end, so that's how balanced operation is= permitted with the basic=20 Ruthrof design shown in the paper. On the same page, a single length of coax is shown giving 1:2 tr= ansformation by the same=20 bootstrapping arrangement, and when the transmision line is shown as= a twisted pair rather than=20 coax, then wrapped on a torroid, it becomes the 1:4 balun beloved of= HF antenna constructors.=20 A natural progression that helps illustrate the concept of a loop of= coax giving one turn more=20 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 wrote: Andy, have a look here : http://www.polyfet.com/HFE0503_Leong.pdf http://www.semelab.com/rf/documents/Push-Pull%20Circuits%20and= %20Wideband%20Transformers.pdf 73, Rik ON7YD - OR7T ----------------------------------------------------------------------= -- Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@b= lacksheep.org] namens Andy=20 Talbot [andy.g4jnt@googlemail.com] Verzonden: dinsdag 9 februari 2010 18:10 Aan: rsgb_lf_group@blacksheep.org; ukmicrowaves@yahoogroups.co= m 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 ----------------------------------------------------------------------= -------- Eingehende eMail ist virenfrei. Von AVG =FCberpr=FCft - www.avg.de Version: 9.0.733 / Virendatenbank: 271.1.1/2691 - Ausgabedatum: 02/1= 6/10 08:35:00 ------=_NextPart_000_0062_01CAAFC4.877764C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
>and I got 950 Watts before the PSU gave up (off 44V).
> So it really was giving more power out than it 'ought= to'
 
Uncertainty of a bird wattmeter with= a 1kW slug=20 would be around +/-50W,
with a 2,5kW element +/-125W.
Power master is a bit better with +/-= =20 30W.
 
73
Clemens
DL4RAJ
 
 
----- Original Message -----
From:=20 Andy Talbot
Sent: Tuesday, February 16,= 2010 8:48=20 PM
Subject: Re: LF: RE: PA match= ing=20 oddity

A follow up to this sage  
 
After much puzzling over the design, and comment here about how= it must=20 be 3:1 teh only solution was to measure it.  So I connecte= d up and=20 measured voltages. Indeed, it does turn out to be 3:1 - &n= bsp;=20 So   how could it deliver 1kW plus...
 
Next, fitted the module to a big heatsink,  got out the 't= elephone=20 exchange' PSU (50V 25 A) and wound up the amp to the max it would=20 give.   Unfortunately the PSU current limited when supplyi= ng only=20 800 or so watts, but by winding teh PSU down to 44V, it current limi= ted at a=20 higher value and I got 950 Watts before the PSU gave up (off=20 44V).    So it really was giving more power out than= it 'ought=20 to'
 
BUT, as Clemens mentioned I'd ignored the saturation element an= d in fact,=20 if used as a switching amp can give well over 1kW.   I'd= used this=20 aspect in the 700W 137kHz Tx, http://www.g4jnt.com/137tx.pdf =20 and forgot it.   Enough said.
 
Anyway, tested the PA, and found it would go down to about= 5MHz=20 where the transformers began to give up, and up to about 20MHz where= the FETs=20 lost gain / efficiency.   So as a 13.56MHz industrial unit= its fine,=20 but of little use as a general HF amp.   BUT, with suitabl= e change=20 of output transformer, could probably be persuaded to give 1.5kW on= 137 or=20 500kHz - if a suitable PSU were to hand.  That's where it sits= =20 now.   Experimentation done, and any further work can wait= for other=20 projects to get pushed of fthe stack.
On 16 February 2010 19:07, Clemens Paul <cpaul@gmx.net>=20 wrote:
Andy,Rik,
 
after thinking a while over the= transformer of=20 Andy's PA and referring to
=
I'm sorry to say that
I'm still quite (say 99,9%) = sure that it=20 is a conventional 1:9 (Z) transfomer.
 
Here are some crucial points whic= h exclude=20 *absolutely* the above design
to be an autotransformer,<= FONT face=3DArial size=3D2>(1:16 or whatever).
1.) Autotransformers provide= no dc=20 isolation, i.e. you have a dc path from
the primary to secondary side.
There is no such dc path= =20 here.
2.)In a bootstrap design the=20 braid of one coax end is connected= to=20 the center
conductor at the= start of the=20 same  coax (1:4) or of the next  coax section (1:9 or=20 higher).
This is not the case in this desi= gn.The=20 center of the secondary is nowhere connected
with a braid.
 
BTW there is no reason to worry= about the=20 theoretical 900W limit in linear mode.
If the PA is slightly overdriven= you get=20 easily one 1dB more power on the fundamental
frequency which is about 1133W so= you have=20 enough margin for losses of the low pass filter
losses etc.
It's very unlikely that this PA= which was used=20 as industrial RF heater=20
was designed to be superlinear.
 
73
Clemens
DL4RAJ
 
 
 
 
----- Original Message -----
To: rsgb_lf_group@blacksheep.org
Cc: ukmicrowaves@yahoogroups.com
Sent: Tuesday, February= 09, 2010=20 10:43 PM
Subject: Re: LF: RE: PA= matching=20 oddity

BINGO -  Tnx Rik, thats it,=20 convincing.  Sorted
 
So my thing  IS 1:4 turns ratio, (1:16 Z ratio)=  just=20 as the calculations said it needed to be, and is indee= d,=20 effectively, an auto transformer.  Otherwise known as a boo= tstrapped=20 coaxial transformer, but just configured with different referenc= e=20 points to confuse everyone. Your second reference= , the=20 Semelab paper, (UKuW see below)  gives the answer. &nb= sp;
 
Look at page 10,   the 1:9 Ruthroff&nbs= p; =20 UnUn .   With just two bits of coax, which= are then=20 bootstrapped up on top of the input to give a 3:1 ratio (for 1:9= =20 impedance).   Add another turn, so three windings are&= nbsp;=20 bootstrapped on top of the primary, rearrange the grounding poin= ts and=20 there, in all its glory, is my mystery.   
 
The reference / grounding points can be shifted as the mosf= et=20 PA  has  two separate, non magnetically=20 linked cores.  This is is just normal push-pull= HF PA=20 practice, and being so normal in its concept, completely hi= des=20 hides a big real advantage - it enables the designer= to float=20 just whatever ternainals need to be floated for balanced / unbal= anced=20 operation, and even to provide DC isolation,   Any con= ductor=20 passing through the core allows one end to be completely Rf = ;decoupled=20 from the other end, so that's how balanced operation is permitte= d with the=20 basic Ruthrof design shown in the paper.
 
On the same page, a single length of coax is shown giv= ing 1:2=20 transformation by the same bootstrapping arrangement, and when= the=20 transmision line is shown as a twisted pair rather than coax, th= en wrapped=20 on a torroid, it becomes the 1:4 balun beloved of HF= =20 antenna constructors.   A natural progression tha= t helps=20 illustrate the concept  of  a loop of coax giving one= turn more=20 than it appears to.
 
It all falls out. 
... life is worth living again ...
... can retire happy ...
 
... now, next job, how to sort out the world financial cris= is ...=20

On 9 February 2010 19:53, Rik Strobbe= <Rik.Strobbe@fys.kuleuven.be> wrote:


Eingehende eMail ist virenfrei.
Von AVG =FCberpr= =FCft - www.avg= .de
Version:=20 9.0.733 / Virendatenbank: 271.1.1/2677 - Ausgabedatum: 02/09/10= 08:35:00=20



Eingehende eMail ist virenfrei.
Von AVG =FCberpr=FCft= - www.avg.de=20
Version: 9.0.733 / Virendatenbank: 271.1.1/2691 - Ausgabedatum:= 02/16/10=20 08:35:00
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