Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mh05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 90FA538000083; Thu, 14 Jun 2012 05:25:54 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Sf6Hu-0006dF-Rf for rs_out_1@blacksheep.org; Thu, 14 Jun 2012 10:24:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sf6Ht-0006d6-Bb for rsgb_lf_group@blacksheep.org; Thu, 14 Jun 2012 10:24:21 +0100 Received: from nm21-vm6.bullet.mail.ird.yahoo.com ([212.82.109.246]) by relay1.thorcom.net with smtp (Exim 4.77) (envelope-from ) id 1Sf6Ho-0008Jg-2p for rsgb_lf_group@blacksheep.org; Thu, 14 Jun 2012 10:24:20 +0100 Received: from [77.238.189.232] by nm21.bullet.mail.ird.yahoo.com with NNFMP; 14 Jun 2012 09:24:14 -0000 Received: from [212.82.108.134] by tm13.bullet.mail.ird.yahoo.com with NNFMP; 14 Jun 2012 09:24:14 -0000 Received: from [127.0.0.1] by omp1039.mail.ird.yahoo.com with NNFMP; 14 Jun 2012 09:24:13 -0000 X-DKIM-Result: Domain=yahoo.co.uk Result=Good and Known Domain X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 989791.99254.bm@omp1039.mail.ird.yahoo.com Received: (qmail 45068 invoked by uid 60001); 14 Jun 2012 09:24:13 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1339665853; bh=i+ZrkQFze3l+E55gVWj1UxqypS87ZVYmWYeuj/yLK1k=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=3sfQm3t4DoaSv1KjoggqvQtpzY+HNdSrX6n/X1X8GKlafMJBIHYEdunLetipaPkHNI+C76YVAMnqW3IlTDJ0+kzo1FcyOPe7eVWtn/3N7Sj02+/wPa9STi+P0T5gk5ry7SsZdIVGVtyaLRc+WOom1ZHwnGY3BTB496eR3QU7crM= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.uk; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=kJYxliRcikRnMzYnR7rMRM0oRXjvQKQhLZRLzbo21eI3S7a5/qvVCXjlWqGkdAJcjj5TaG27XcVfzKK77QSXldjGBO10l/Z4jIxdibkwk1aWMl/RLwf8nojFPP0i97vvMZiPWRTXctKxlBrxwEyAsiHFuaGmm5w7GJadbT64tsU=; X-YMail-OSG: NEj.2Y8VM1nVdLmxV7jZeDilkuIFQy1ujB9AN9yUAfD9iz1 E0JHifUsD Received: from [86.164.58.72] by web171602.mail.ir2.yahoo.com via HTTP; Thu, 14 Jun 2012 10:24:13 BST X-Mailer: YahooMailWebService/0.8.118.349524 References: <1339438549.67345.YahooMailNeo@web171605.mail.ir2.yahoo.com> <85F124CBD59C48FEB97567F3B69B2AC1@lindavideo> <1339499711.77638.YahooMailNeo@web171605.mail.ir2.yahoo.com> <006a01cd48cb$f2e1aed0$0401a8c0@xphd97xgq27nyf> <1339599103.18960.YahooMailNeo@web171605.mail.ir2.yahoo.com> <4FD900B4.7020905@iup.uni-heidelberg.de> <1339628355.5649.YahooMailNeo@web171601.mail.ir2.yahoo.com> <51AD766F39DB486D83959D6053278D61@AGB> Message-ID: <1339665853.36124.YahooMailNeo@web171602.mail.ir2.yahoo.com> Date: Thu, 14 Jun 2012 10:24:13 +0100 (BST) From: M0FMT To: "rsgb_lf_group@blacksheep.org" In-Reply-To: <51AD766F39DB486D83959D6053278D61@AGB> MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi Again Graham The FL2000b has 2 x 572B triodes in parallel grounded grid. These are directly heated tubes and have carbon anodes. 1/ they give a good light display and 2/ you can tune up by observing the "blush" on the anodes (if you wanted to). I have had it years hardly use it got after the original owner had had it retubed and serviced. Makes a bit of difference on 80m when the going gets difficult. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.82.109.246 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (m0fmt[at]yahoo.co.uk) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 FSL_FREEMAIL_2 FSL_FREEMAIL_2 0.0 FSL_FREEMAIL_1 FSL_FREEMAIL_1 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 1c9013e8bbe5a838808a955a10faa99b Subject: Re: LF: RE: Class E etc Content-Type: multipart/alternative; boundary="1507048413-1119496326-1339665853=:36124" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=HTML_50_60, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,TO_ADDRESS_EQ_REAL 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-SCORE: 1:2:510719712:93952408 X-AOL-SCOLL-URL_COUNT: 1 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d006.1 ; domain : yahoo.co.uk DKIM : fail x-aol-sid: 3039ac1d60d94fd9ae2110a2 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --1507048413-1119496326-1339665853=:36124 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Again Graham=0A=0AThe FL2000b has 2 x 572B triodes in parallel grounded = grid. These are directly heated tubes and have carbon anodes. 1/ they give = a good light display and 2/ you can tune up by observing the "blush" on the= anodes (if you wanted to). I have had it years hardly use it got after the= original owner had had it retubed and serviced. Makes a bit of difference = on 80m when the going gets difficult.=0A=0AAs with your hipower thyratron a= ll you need is a good multi Kw PSU.=A0 Oh and some x-ray protection?=0A=0AI= spent a bit of time in the MoD back in the 90s=A0and one radar I used to v= isit was on Scotland's east coast it was very old but nothing to replace it= . The whole transmitter cabin rotated with the antenna. God knows what the = power O/P was. The power pickup was via a pair of circular channels of merc= ury and the bottles in the cabin where a sight to see probably kicked out a= s much x-ray as they did microwave.=0AWe were running a mobile radar fairly= modern still thermionic had=A0a massive single Klystron 1MW pulse! On site= was a new solid state phased array unit there to replace the old rotary ca= bin Joby but wasn't having a happy time. A major complaint was the ops coul= dn't turn the rx gain up to see the sparkles to be confident it was working= ..... hee! The new systems have a lot of software processing before the dis= play reaches the scopie. Hasen to add I am not a radar expert in any way. W= hen you work for that outfit you get thrown into jobs you know nothing abou= t. I was mainly on comms infrastructure and didn't know much about that eit= her.... ;-0.=0A=0AOh and yes used 4cx250s and 4cx150=A0in 2m and 70cms PAs = the one for 70 took off and recked my transverter. They were designs out of= the old RSGB VHF handbook when I were a Jaite!=0A=0AI am not going back to= Hi power Tube rigs again its not necessary when hi power FETs are so cheap= .=0A=0AAny way this all a bit off topic. Its bit like the last day at schoo= l before the summer break on this reflector doing what you like before it g= ets turned off.... hee! And not much to do with Class d/e or any other lett= er of the alphabet.. What I have to sort out is my RX for MF/LF it is not g= ood, need some ideas?=0A=0A=A073 es GL Pete M0FMT IO91UX=0A=0A=0A__________= ______________________=0A From: Graham =0ATo: rsgb= _lf_group@blacksheep.org =0ASent: Thursday, 14 June 2012, 1:55=0ASubject: R= e: LF: RE: Class E etc=0A =0A=0AOk Pete .. blow up ? !!......Depends on th= e=A0 tubes=A0 : ))=A0 http://home.comcast.net/~n6jv/data/6C21.pdf =0A=0AThi= s=A0 is what=A0 you need=A0 (with a=A0 bit of re-work)=A0 =0A.....=A0 =0Ah= ttp://www.radartutorial.eu/08.transmitters/tx06.en.html =0AVK or Bust=A0 !!= =0A=0AFL2000=A0=A0 , with=A0 2=A0 x 813=A0 ?=A0 nice=A0 =0Aamp,=A0=A0 my= =A0 skanti=A0 trp5000=A0=A0 has=A0=A0=A0 =0A2 x=A0=A0=A0 4cx250-b=A0=A0 in = the=A0 PA=A0 runs well=A0 =0A1.8/30 Mhz=A0 ,=A0=A0 I=A0 use=A0=A0 2=A0=A0 = =0Acombined=A0 skanti 250 watt solid state 50v=A0 =A0linear amps=A0 =0Awith= the=A0 ma1723 for=A0 LF>Hf=A0 , wide=A0 band=A0 , =0A=A0just change the=A0= ATU=A0 hi .....=A0=A0 could=A0 do=A0 =0Awith a=A0 simple=A0 class e/d for= =A0 500=A0 as=A0 the=A0 =0Aab1=A0 amps=A0 are a little=A0 power hungry .. = =0A=0AG.. =0A=0A=0A =0AFrom: M0FMT =0ASent: Wednesday, June 13, 2012 11:59= PM =0ATo: rsgb_lf_group@blacksheep.org =0ASubject: Re: LF: RE: Class E et= c =0A =0AHi Stefan and Graham =0A=A0 =0AThanks for the comments. None of my= MF/LF tx.s run more that =0A160watts although by seriesing a couple of PSU= s one with a floating ground I can run =0Aabout 280Watts o/p from the TX. I= don't like seriesing the PSUs so =0Aonly do it during experimenting not on= the air. Need to build a new=A0high =0Avoltage PSU 100V at a good current = =0Arating.=A0The rigs are FET PA IRF840 etc=A0mostly xtal controlled or xta= l mixer type master oscillator (but do have DDS), into a FET driver chip. A= nd set them as described =0Aearlier. =0A=A0 =0AI have played with High powe= r Audio amps on 136kc/s transforming the =0ALow impedance to 50 ohms+/- usi= ng Ferrite cored transformer to drive the antenna =0Atuner. Front end curre= ntly popped!! =0AUsing it for QRSS overnight.Will get it =0Aback on soon. = =0A=A0 =0AMy interest in Valve or Tube TX is a side issue and am not advoca= ting =0Athem for serious modern MF/LF work. =0AHowever there is no reason w= hy not. =0A=A0 =0AI have made a couple of TUBE QRP rigs one for 160/80 abou= t 4/5 watts out Choke modulated AM =0Aand CW and FSK. Worked most of UK on = AM =0Aon 3.615megs. The second is a copy for 500kc/s was originally VFO con= trolled but now is again xtal mixer vxo. They use 6CL6 video tubes in the P= A. The 500kc/s tube tx only runs a watt o/p yet to figure out =0Awhy, it sh= ould be about 5watts. How=A0ever on my new found Opera4 =0Ahave=A0been repo= rted in PA0 land (on the limit). =0AI have built and still got one or two= =A0807 PAed rigs for 80m knocking about. Plus a Louis Varney design made by= an unknown amateur in the =0A1950s and a Codar T5 and a push pull 807 =0Ar= ig on the stocks.... but probably won't get finished. Plus an FL2000B. This= to =0Ashow my thermionic credentials.... hee! =0A=A0 =0AFor shear interest= I would like to try and make a high efficiency =0ATUBE PA but probably won= 't get around to it. But that 1960s RCA AM BC TX design =0Alooks interestin= g but probably very dodgy to set up, stability and all. Graham =0Ayour arc = tubes is all very well but what I have read is that they have a =0Atendency= to blow up...... and so do FETs ok so no change there then. =0A=A0 =0AMy c= urrent limitation to power Stefan is lack of a single stable PSU with a cou= ple of KW output. The =0Aantenna is now reduce to 35ft up and 128ft top. = =0A=A0 =0AI don't have a good RX for MF/LF what I have are deaf by others s= tandards and this is my =0Amain area of interest at the moment. I have used= a TS50 and a TS690s full =0Afilters=A0plus a couple of direct conversion H= B=A0RX=A0with active filers and notch. =0AFront ends have gone from dual ga= te mosfet to straight into the mixer but S/N is still poor evidenced by WSP= R and Opera reports I give to other station who are being received much bet= ter elsewhere. If any =0Aone can help me with that then it would make life = here on MF/LF=A0a lot better. =0A=A0 =0AKeep the bands =0Aopen and may get= to work you Stefan now you have 472/9....... why the delay in the UK???? = =0A=A0 =0A73 es GL Pete M0FMT IO91UX=0A=0A=0A______________________________= __=0AFrom: Stefan Sch=E4fer =0ATo: r= sgb_lf_group@blacksheep.org =0ASent: Wednesday, 13 June 2012, =0A22:05=0ASu= bject: Re: LF: RE: =0AClass E etc=0A=0A=0AHi Pete, LF, =0A=0AOn 137 kHz or = 500 kHz you can quite easy achieve 95% =0Aefficiency with a class E PA. BTW= a ferrite transformer is not needed! So if =0Ayour antenna provides stable= resonance and impdedance and if you like to play arround a bit to obtain t= he best efficiency (not the highes output power), a well designed class E = =0APA is definitifely a good choice! 1 kW RF =0A(CW, key down!) is possible= with a single IRFP MOSFET. =0AI =0Ahardly expect that you will get such an= efficiency with a tube amp but i can =0Aunderstand the fascination of a gl= owing tube in a dark shack, although i'm not from the tube generation ;-) T= he first =0Apower amplifier i heard of was a 2N3055 in the late 80s as i wa= s 12 year old or =0Aso :-)=0A=0A73, Stefan/DK7FC=0A=0A=0AAm 13.06.2012 16:5= 1, schrieb M0FMT: =0AWell shoot me down with my britches on fire! =0A>=A0 = =0A>Mal =0A>I have just found an article on an enhanced Class C in Tube a= mplifiers By RCA. =0A>I have heard of higher efficiency Valve amps but nev= er gave them any time because I thought they used special valves to achiev= e the fast response. But apparently not, it relies on a tuned circuit in t= he anode and cathode. The cathode LC being set at the third harmonic of th= e anode one. By combining the drive wave with the third hamonic you get a v= ery fast rising pulse type=A0wave at the drive frequency in the PA tuned c= ircuit as with a class D/E solid state amp. URL is ........ http://nrcdxas= .org/articles/bta5t/ =0A>=A0 =0A>I think the point about this is that it w= orks OK for fixed frequency TX's like broadcast transmitters and the like. = And probably will work OK for us on LF with such narrow allocations where = we may get away with one set up. =0A>=A0 =0A>Now to see if it is scalable = to lower power video tubes. =0A>=0A>73 es GL Pete M0FMT IO91UX=0A>=0A>From= : mal hamilton =0A>To: rsgb_lf_group@blacksheep.org = =0A>Sent: Tuesday, 12 June 2012, 19:48=0A>Subject: Re: LF: RE: Class E et= c=0A>=0A>=0A>Pete es Co =0A>The class C tube amplifer is the nearest you ca= n get to class D or E and well designed would=A0produce 70% efficiency. = =0A>The class D or E is not really an amplifier in the convential sense it = is merely an RF switch at the frequency of interest and the voltage genera= ted is increased by a step up transformer with probably 80% to 90% efficie= ncy if you are lucky. =0A>Like some have said a tube amp is more robust an= d tolerant of mismatch to antenna without smoke. Fets are good but can go = bang if one is not careful about matching to load. =0A>I have some Dentron= amps for the HF bands and they have been going for years. =0A>Fets are pr= obably more manageable, compact =A0and safer regarding voltages, beware of= tubes with voltages of a few K/volts at high current, like an electric c= hair!! =0A>73 de mal/g3kev =0A>=0A>----- Original Message ----- =0A>>From:= M0FMT =0A>>To: rsgb_lf_group@blacksheep.org =0A>>Sent: Tuesday, June 12,= 2012 11:15 AM =0A>>Subject: Re: LF: RE: Class E etc =0A>>=0A>> =0A>>Hi Ke= n =0A>>=A0 =0A>>I believe you can operate=A0some thermionic devices in hig= her classes than C=A0but they generally lack the frequency response of a m= odern FET. I won't go into figures but just think about it. The high effic= iency output stage has to operate like a switch it is not actually an ampli= fier. The faster it changes state from fully on with ultra low resistance = to fully off (which=A0means a device that will operate=A0well into the=A0= VHF)=A0the higher the efficiency. If you have a device that is barely rate= d to say a couple of megs its not going to be much good (in terms of what = we are talking about)=A0at 500kc/s. Remember you are trying to get the mag= netic field in the inductor to rise and collapse at a very fast rate in-ord= er to generate a high electromagnetic field at the drive frequency. We are= not talking sine waves here as a scope on the drain will show. Although a= scope on the output side of the drain inductor will show quite a clean lo= oking sine wave. Try it. =0A>>=A0 =0A>>That chart at the end of that PDF file is very= clever and is the guide=A0I use to bring a PA into optimum performance. = =0A>>=A0 =0A>>What I was trying to say is that the math is all very well bu= t if you are trying to make a practical and=A0efficient CW TX for LF then= =A0there is enough empirical data from following the guide lines lines sho= wn on the sites I have posted=A0that will get you a good TX. If you want a= doctorate in theoretical physics to bamboozle you colleagues then that wil= l detract from the time it takes to build a very interesting high power, = efficient=A0TX design well within anybodies capabilities.=A0The GW3UEP desi= gn being IMHO a very good (Scalable) example with no=A0RadCom=A0style unobt= ainium in the components listing. =0A>>=0A>>73 es GL Pete M0FMT IO91UX=0A>>= =0A>>From: Ken =0A>>To: rsgb_lf_group@blackshe= ep.org =0A>>Sent: Monday, 11 June 2012, 22:09=0A>>Subject: LF: RE: Class = E etc=0A>>=0A>>=0A>> =0A>>Hi Pete. =0A>>About 40 years ago my integration w= as quite good, liked doing 2nd order differential equations, partial inte= gration and integration by parts, the one thing I had big problems with wa= s 3 dimensional integration of a point in free space . =A0=A0Looking at so= me of the sites my Class C MOSFET PA is probably more like Class E by defau= lt. The reason I like valves is because they are very forgiving devices un= like semiconductors, also the keep the shack and the cat warm. =0A>>=A0 = =0A>>73s =0A>>=A0 =0A>>Ken =0A>>=A0 =0A>>M0KHW =0A>>=A0 =0A>> =0A>>From:own= er- rsgb_lf_group@blacksheep.org [mailto: owner- rsgb_lf_group@blacksheep.o= rg ] On Behalf Of M0FMT=0A>>Sent: 11 June 2012 19:16=0A>>To: rsgb_lf_group= @blacksheep.org=0A>>Subject: LF: Class E etc =0A>>=A0 =0A>>=A0Hi Ken =0A= >>=A0 =0A>>Ha ha Stefan, how good is=A0your Integration Ken? =0A>>=A0Here a= re a couple of sites that should answer your questions. You need a good du= mmy load and a good oscilloscope. Setting the conditions for the amplifier= is to do with=A0 A/ the correct driver preferably using a FET drive chip = (like TC4422 non and TC4421 inverting) that will turn the FET fully=A0on an= d fully off on each cycle. Very fast rise time with accurate=A0on off timi= ng (mark / space). Ensuring the=A0max permitted gate voltage for the FET= =A0is not exceeded otherwise they pop, look out for transients, a diode cl= amp helps.=A0 B/ Setting the shunt capacitance and inductance=A0in the dra= in=A0circuit can be done empirically See article below. Then follow it wit= h=A0a=A0low pass filter, although the output wave will be surprisingly cle= an.=A0Calculating the values is difficult as you don't necessarily know al= l the starting=A0parameters and in any case=A0the result is=A0going to wid= e of the mark. The site below will gives some starting values. Best to use 'Scope measurements to set the output conditions. You are looking for= fast, very fast On / Off rise times. Gate drive and understanding the dra= in circuit is the key. These amplifiers are capable of incredibly good ef= ficiency well above a dodgy class C amp. This means the heat dissipation f= rom the FET is very low at high power=A0giving cool heat-sinks! =0A>>=A0T= he GW3UEP (do a web search) single ended design is capable good efficiency= =A0and high power depending upon the FET used and Drain supply voltage. I = have modified one to run reliably at 140watts and is capable of almost twi= ce that into a dummy load with a heat sink that is fairly cool. Adjusting = L and C empirically using the 'scope to get the correct drain wave shape f= or max efficiency is the way to go. The article below shows you what you a= re looking for. I set my TX up into a 50 Ohm dummy load adjusting L and C = to get the correct drain wave shape on the 'scope then measuring the peak = voltage across the Dummy load.=A0I then transfer my=A0connector from the D= ummy load to the input of the tuned transformer in the antenna up-lead. I = adjust the coupling link to give the same peak voltage=A0across the tuner = link turns. You are not looking for maximum peak just the sames as across = the dummy load indicating a 50ohm match.=A0This is done by either=A0adding or reducing=A0the number of turns (about two turns) along= with bringing the the transformer to resonance by measuring the peak=A0up= -lead current, here you are looking for the maximum peak.=A0=A0 =0A>>=A0= =0A>>Oh yes and WIMA high voltage high value capacitors from Maplin work w= ell. =0A>> =0A>>=A0Read the articles and search info on class E amplifiers= .=A0 =0A>>=A0 =0A>>=A0 =0A>>For some bed time reading but ignor the math l= ook at the Tuning Procedure and the pictures at the end which tell it all = really..... http://www.cs.berkeley.edu/~culler/AIIT/papers/radio/Sokal%20AA= CD5-poweramps.pdf =0A>>=A0 =0A>>For design ideashttp://www.classeradio.com= / =0A>>=A0 =0A>>For a good practical circuit for a single ended amp=A0tha= t =A0is a scalable surefire design, no need to reinvent the wheel. =0A>>ht= tp://www.gw3uep.ukfsn.org/ =0A>> =0A>>=A0For antennas and antenna feed meth= ods a "look no where else site" =0A>> =0A>>http://www.strobbe.eu/on7yd/1= 36ant/ =0A>>=A0 =0A>>73 es GL Pete M0FMT IO91UX=0A>>=0A>>=A0=0A>=0A> --1507048413-1119496326-1339665853=:36124 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
<= /div>
Hi Again Graham
 
The FL2000b has 2 x 57= 2B triodes in parallel grounded grid. These are directly heated tubes and h= ave carbon anodes. 1/ they give a good light display and 2/ you can tune up= by observing the "blush" on the anodes (if you wanted to). I have had it y= ears hardly use it got after the original owner had had it retubed and serv= iced. Makes a bit of difference on 80m when the going gets difficult.
=
 
As with your hipower thyratron all you need is a good= multi Kw PSU.  Oh and some x-ray protection?
 
I spent a bit of time in the MoD back in the 90s and one radar I us= ed to visit was on Scotland's east coast it = was very old but nothing to replace it. The whole transmitter cabin rotated with the antenna. God knows what the power O/P was. The power pick= up was via a pair of circular channels of mercury and the bottles in the ca= bin where a sight to see probably kicked out as much x-ray as they did micr= owave.
We were running a mobile radar fairly modern still thermio= nic had a massive single Klystron 1MW pulse! On site was a new solid s= tate phased array unit there to replace the old rotary cabin Joby but wasn't having a happy time. A major= complaint was the ops couldn't turn the rx gain up to see the sparkles to be confident it was working...= .. hee! The new systems have a lot of software processing before the displa= y reaches the scopie. Hasen to add I am not a radar expert in any way. When= you work for that outfit you get thrown into jobs you know nothing about. = I was mainly on comms infrastructure and didn't know much about that either.... ;-0.
 
Oh and yes used 4cx250s and 4cx= 150 in 2m and 70cms PAs the one for 70 took off and recked my transver= ter. They were designs out of the old RSGB VHF handbook when I were a Jaite= !
 
I am not going back to Hi power Tube rigs agai= n its not necessary when hi power FETs are so cheap.
 
=
Any way this all a bit off topic. Its bit like the last day at school = before the summer break on this reflector doing what you like before it get= s turned off.... hee! And not much to do with Class d/e or any other letter= of the alphabet.. What I have to sort out is my RX for MF/LF it is not goo= d, need some ideas?
 
<= div> 73 es GL Pete M0FMT IO91UX
From: Gr= aham <g8fzk@g8fzk.fsnet.co.uk>
To: rsgb_lf_group@blacksheep.org
Sent: Thursday, 14 June 2012, 1:55
Subject: Re: LF: RE: Class E etc

=0A=0A =0A =0A
=0A
Ok = Pete .. blow up ? !!......Depends on the  tubes  : ))  http://home.comcast.net/~n6jv/data/6C21.pdf
= =0A
 
=0A
This  is what  you need  (with a=   bit of re-work)  =0A..... 
=0A=0A
VK or Bust  !!
=0A
 <= /div>=0A
FL2000   , with  2  x 813  ?  ni= ce  =0Aamp,   my  skanti  trp5000   has&= nbsp;   =0A2 x    4cx250-b   in the = ; PA  runs well  =0A1.8/30 Mhz  ,   I  use&nb= sp;  2   =0Acombined  skanti 250 watt solid state 50v&n= bsp;  linear amps  =0Awith the  ma1723 for  LF>Hf&nb= sp; , wide  band  , =0A just change the  ATU  hi .= ....   could  do  =0Awith a  simple  class e/= d for  500  as  the  =0Aab1  amps  are a litt= le  power hungry ..
=0A
 
=0A
G..
=0A 
=0A
=0A

=0A
=0A
Hi Stefan and Graham
=0A
 
=0A
Thanks for the comm= ents. None of my MF/LF tx.s run more that =0A160watts although by seriesing a couple of =0APSUs one wit= h a floating ground I can run =0Aabout 280Watts o/p from the TX. I don't li= ke seriesing the PSUs= so =0Aonly do it during experimenting not on the air. Need to build= a new high =0Avoltage PSU 100V at a good current =0Arating. The rigs ar= e FET P= A IRF84= 0 etc mostly xtal controlled or xtal =0Amixer type master oscillator (but do have = DDS), into a = FET driver chip. And set them as described =0Aearlier.
= =0A
 
=0A
I have played with High powe= r Audio amps on 136kc/s transforming the =0ALow impedance to 50 ohms+/- usi= ng Ferrite cored transformer to drive the antenna =0Atuner. Front end curre= ntly popped!! =0AUs= ing it for QR= SS overnight.Will get it =0Aback on soon.
=0A
=  
=0A
My interest in Valve or Tube TX is a side = issue and am not advocating =0Athem for serious modern MF/LF work. =0AHowever the= re is no reason why not.
=0A
 
=0AI have made a couple of TUBE QRP rigs one for 160/80 about 4/5 watts out= Choke modulated AM =0Aand CW and FSK. Worked most of UK on AM =0Aon 3.615megs. T= he second is a copy for 500kc/s was originally VFO controlled but now is again xtal mix= er vxo= . They use 6CL6 video tubes in the PA. The 500kc/s tube =0Atx only runs a watt o/= p yet to figure out =0Awhy, it should be about 5watts. How ever on my = new found Opera4 =0Ahave been reported in PA0 land (on the limit).
=0A
I have built and still got one or two 807 PAed rigs f= or 80m knocking about. Plus a Louis Varney design made by an unknown amateur in t= he =0A1950s and a Codar T5 and a push pull 807 =0Arig on the stocks.... but proba= bly won't get finished. Plus an FL2000B. This to =0Ashow my thermionic cred= entials.... h= ee!
=0A
 
=0A
For s= hear interest I would like to try and make a high efficiency =0ATUBE PA but= probably won't get around to it. But that 1960s RCA AM BC TX design =0Aloo= ks interesting but probably very dodgy to set up, stability and all. Graham= =0Ayour arc tubes is all very well but what I have read is that they have = a =0Atendency to blow up...... and so do FETs =0Aok so no change there then.=0A
 
=0A
My current limitation to p= ower Stefan is lack of a single stable =0APSU with a couple of KW output. The =0A= antenna is now reduce to 35ft up and 128ft top.
=0A
=  
=0A
I don't have a good RX for MF/LF what I have are= deaf by others standards and this is my =0Amain area of interest at the mo= ment. I have used a TS50 and a TS690s full =0Afilters plus a couple of= direct conversion HB RX with active filers and notch.
=0A<= div>Front ends have gone from dual gate mosfet to straight into the mixer b= ut S/N is still poor evidenced b= y WSPR= and Opera reports I give to other station who are being =0Areceived much better elsewhere. If= any =0Aone can help me with that then it would make life here on MF/LF a l= ot better.
=0A
 
=0A
Keep the bands =0Aopen and = may get to work you Stefan now you have 472/9....... why the delay in the UK????
=0A
=  
=0A
73 es GL Pete M0FMT IO91UX
=0A
=0A
=0A
=0A
From: Stefan Sch=E4fer =0A<Stefan.Schaefer@iup.uni= -heidelberg.de>
To: = rsgb_lf_group@blacksheep.org =0A
S= ent: Wednesday, 13 June 2012, =0A22:05
Subject: Re: LF: RE: =0AClass E etc

=0A
=0A
Hi Pete, LF,

On 137 kHz = or 500 kHz you can quite easy achieve 95% =0Aefficiency with a class E PA. = BTW a ferrite transformer is not needed! So if =0Ayour antenna provides sta= ble resonance and impdedance and if you like to play arround a bit to obtain the best e= fficiency (not the highes output power), a well designed class E =0APA is definitifely = a good choice! 1 kW RF =0A(CW, key down!) is possible with a single IRFP MOSFET.
I = =0Ahardly expect that you will get such an efficiency with a tube amp but i= can =0Aunderstand the fascination of a glowing tube in a dark shack, altho= ugh i'm not from the tube generation ;-) The first =0Apower amplifier i heard of = was a 2N3055 in the late 80s as i was 12 year old or =0Aso :-)

73, S= tefan/DK7FC<= br>

Am 13.06.2012 16:51, schrieb M0FMT: =0A
=0A=
=0A
=0A
=0A
=0A
= Well shoot me down wi= th my =0A britches on fire!
=0A
 
=0A
Mal
=0A
I have just found an article on= an enhanced Class C in Tube =0A amplifiers By RCA.
=0A
I have heard of higher efficiency =0A Valve amp= s but never gave them any time because I thought they used special =0A val= ves to achieve the fast response. But apparently not, it relies on a tuned = =0A circuit in the anode and cathode. The cathode LC being set at the thir= d =0A harmonic of the anode one. By combining the drive wave with the thir= d hamonic you get a very fast rising pulse =0A type wave at the drive frequ= ency in the PA tuned circuit as with a class =0A D/E solid state amp. URL = is ........ http://nrcdxas.org/articles/bta5t/
=0A =
 
=0A
I think the point about this is =0A that it works OK for fixed freque= ncy TX's like broadcast transmitters and the like. And probably =0A will work OK= for us on LF with such narrow allocations where we may get away =0A with = one set up.
=0A
=  
=0A
Now to see if it is scalab= le to =0A lower power video tubes.
=0A
 
=0A
73 es GL Pete M0FMT IO91UX
=0A
=0A
=0A
Fro= m: mal h= amilton <g3kevmal@talktalk.net>
To: rsgb_lf_= group@blacksheep.org =0A
Sen= t: Tuesday, 12 June 2012, =0A 19:48
Subject: Re: LF: RE: =0A Class E etc

=0A
=0A
=0A
Pete es Co
=0A
The class C tube <= span id=3D"yiv77121966misspell-65" class=3D"yiv77121966mark">amplifer is the nearest you can get to class D or E and well =0A designed would&n= bsp;produce 70% efficiency.
=0A
The = class D or E is not really an amplifier in the convential sense it is merely an R= F switch at =0A the frequency of interest and the voltage generated is inc= reased by a step up =0A transformer with probably 80% to 90% efficiency if= you are lucky. =0A
=0A
Like some ha= ve said a tube amp is more robust and =0A tolerant of mismatch to antenna = without smoke. Fets are good but can go bang if one is not careful about =0A mat= ching to load.
=0A
I have some Dentron amp= s for the HF bands and they have been going for =0A years.
=0A=
Fets are probably =0A more manageable, compact  = ;and safer regarding voltages, beware of tubes =0A with voltages of a few = K/volts at high current, like an electric =0A chair!!
=0A 73 de mal/g3kev
=0A
 
=0A
=0A
----- Original Message -----
=0A
From: M0FMT
=0A
To: rsgb_lf_= group@blacksheep.org =0A
=0A
Sent: Tuesday, June 12, 2012 11:15 =0A AM
=0A =
Subject: Re: LF: RE: Cl= ass E etc
=0A

=0A
=0A
<= span>Hi Ken
=0A
 
=0A
I believe you = =0A can operate some thermionic devices in higher classes than C&nb= sp;but =0A they generally lack the frequency response of a modern FET. I won't go int= o figures but just t= hink about =0A it. The high eff= iciency =0A output stage has to operate like a switch it i= s not actually an amplifier. =0A The faster it changes state from fully = on with ultra low resistance to fully =0A off (which means a device= that will operate well into =0A the VHF) the higher the = efficiency. If you have a device that is =0A barely rated to say a coupl= e of megs its not going to be much good (in terms =0A of what we are tal= king about) at 500kc/s. Remember you are trying to =0A get the magn= etic field in the inductor to rise and <= span>collapse at a very fast =0A rate in-order to =0A generate a hig= h electromagnetic field at the drive frequency. We are not =0A talking s= ine waves here as a scope on the drain will show. Although a scope =0A o= n the output side of the drain inductor will show quite a clean looking =0A= sine wave. Try it.
=0A
 
=0A=
That chart at the end of that PDF =0A file is very clever and is the g= uide I use to bring a PA into optimum =0A performance.
= =0A
 
=0A
What I was trying to= say is that the math is all very well but if =0A you are trying to make= a practical and efficient CW TX for LF =0A then there is enou= gh empirical data fr= om following =0A the guide lines lines shown on the sites I have posted&= nbsp;that will get =0A you a good TX. If you want a doctorate in theoret= ical physics to bamboozle you colleagues then that will =0A detract from the time it takes to build a very interesting high power,= =0A efficient TX design well within anybodies capabilities. T= he GW3UEP =0A design be= ing IMHO a very good (Scalable) example with no RadCom style unobtainium in the components = listing.
=0A
 
=0A
73 es GL Pete M0FMT IO91UX
=0A
=0A
=0A
From: Ken <ken.h.w= right@btinternet.com>
To: rsgb_lf_group@blacksheep.org =0A =
Sent: Monday, 11 Jun= e =0A 2012, 22:09
Subject: LF: =0A RE: Class E etc

=0A
=0A