Return-Path: Received: from mtain-md03.r1000.mx.aol.com (mtain-md03.r1000.mx.aol.com [172.29.96.87]) by air-mb08.mail.aol.com (v127_r1.1) with ESMTP id MAILINMB084-a8064b7bd02e1d7; Wed, 17 Feb 2010 06:17:02 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-md03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7F26F380002B7; Wed, 17 Feb 2010 06:17:00 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Nhhsc-0007UC-4h for rs_out_1@blacksheep.org; Wed, 17 Feb 2010 11:15:42 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Nhhsb-0007U3-9X for rsgb_lf_group@blacksheep.org; Wed, 17 Feb 2010 11:15:41 +0000 Received: from mail-bw0-f224.google.com ([209.85.218.224]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NhhsZ-0007o4-8T for rsgb_lf_group@blacksheep.org; Wed, 17 Feb 2010 11:15:41 +0000 Received: by bwz24 with SMTP id 24so4144991bwz.29 for ; Wed, 17 Feb 2010 03:15:32 -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=b6GO5qbu6cjzJ5pXTIzGOphaVSzx9T4ZUAGTLkG05k8=; b=BzcMWc6wYLhEXUQWDX9UBCEtoHpEaHqBfaf5uaaWFhbeYeO4aFYPw6Z07mDVF+/g9t PZrnh4hH1uBZhdxQUjgwzBA/+GWDtIRBrlk0BX84ZMCK+9/Mc24/D8jIxZRQ6WJcBGaz 8FubtkXlP79aS+ctvCDt/C1l8tRSmuPV269xw= 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=BwCyjw0azg4pD9er5PRPzjTrt/WEPMKn/tsLXL78YFbjC0FKNqselZLC45RXsP2N7C 3lczHW45L32nEHw+xicW2ep7yV3JoZ/7St9oNx9lB4f8rQmw4EH5oghhsSCz0bJOYpyZ 479qQYaryKr4TojWPLY1MuejKA+iNFUT2YoeA= MIME-Version: 1.0 Received: by 10.204.15.17 with SMTP id i17mr5218072bka.173.1266405332004; Wed, 17 Feb 2010 03:15:32 -0800 (PST) In-Reply-To: <006601caafbc$28de4c10$0201a8c0@Clemens04> References: <006501caaf3b$53ddb350$0201a8c0@Clemens04> <006601caafbc$28de4c10$0201a8c0@Clemens04> Date: Wed, 17 Feb 2010 11:15:31 +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=00032555a7eef4af6e047fc9f782 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-m264.1 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039ac1d60574b7bd02c13a4 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --00032555a7eef4af6e047fc9f782 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I don't use a Bird wattmeter. Don't trust any directional type of meter= for proper power measurements. I have a 1GHz specified 30dB rated 1kW Bird attenuator (calibrated) plus= HP 432 power meter (reasonably well calibrated) so I reckon power measuremen= t is to within 0.2dB However, trying to get more than 1kW would overlaod the attenuator, which= is a very nice little (!) bit of kit to have so probably not a good idea Andy www.g4jnt.com On 17 February 2010 10:29, Clemens Paul wrote: > >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 ----- > *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 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 deliv= er > 1kW plus... > > Next, fitted the module to a big heatsink, got out the 'telephone > exchange' 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 watt= s, > 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 gi= ving > 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 aspec= t in > the 700W 137kHz Tx, http://www.g4jnt.com/137tx.pdf and forgot it. > Enough said. > > Anyway, tested the PA, and found it would go down to about 5MHz where th= e > 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. Experimentatio= n > done, and any further work can 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 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 desig= n >> 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 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 lin= ear >> 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 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 calculatio= ns >> said it needed to be, and is indeed, effectively, an auto transformer. >> Otherwise known as a bootstrapped coaxial transformer, but just configu= red >> with different reference points to confuse everyone. Your second refere= nce, >> the Semelab paper, (UKuW see below) gives the answer. >> >> Look at page 10, the 1:9 Ruthroff UnUn . With just two bits of co= ax, >> 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 it= s >> 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-p= ull >> HF PA practice, and being so normal in its concept, completely hides hi= des 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 allow= s one >> end to be completely Rf decoupled from the other end, so that's how bal= anced >> 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 wrap= ped >> on a torroid, it becomes the 1:4 balun beloved of HF antenna constructo= rs. >> 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%20Wideb= and%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: 02/09/1= 0 >> 08:35:00 >> >> > ------------------------------ > > > Eingehende eMail ist virenfrei. > Von AVG =FCberpr=FCft - www.avg.de > Version: 9.0.733 / Virendatenbank: 271.1.1/2691 - Ausgabedatum: 02/16/10 > 08:35:00 > > --00032555a7eef4af6e047fc9f782 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
I don't use a Bird wattmeter.=A0 Don't trust any directional= type of meter for proper power measurements.=A0
=A0
I have a=A0 1GHz specified 30dB rated 1kW Bird attenuator (calibrated= ) plus HP 432 power meter (reasonably well calibrated)=A0 so I reckon powe= r measurement is to within 0.2dB
=A0
However, trying to get more than 1kW would overlaod the attenuator,= which is a very nice little (!) bit of kit to have so probably not a good= idea
=A0
On 17 February 2010 10:29, Clemens Paul <cpaul@gmx.net> wrote:
>and I got=A0950 Watts before the PSU gave up (off 44V).
>=A0So it really was giving more power out than it 'ought to&#= 39;
=A0
Uncertainty of a bird wattmeter with= a 1kW slug would be around +/-50W,
with a 2,5kW=A0element +/-125W.
Power master is a bit better with +/-= 30W.
=A0
73
Clemens
DL4RAJ
=A0
=A0
----- Original Message -----
Sent: Tuesday, February 16, 2010 8:= 48 PM
Subject: Re: LF: RE: PA matching od= dity

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 forg= ot it.=A0=A0 Enough 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=



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


--00032555a7eef4af6e047fc9f782--