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: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 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 v53ECidN017800 for ; Sat, 3 Jun 2017 16:12:46 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dH9dR-0006m3-0C for rs_out_1@blacksheep.org; Sat, 03 Jun 2017 15:02:33 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dH9dB-0006lp-5D for rsgb_lf_group@blacksheep.org; Sat, 03 Jun 2017 15:02:17 +0100 Received: from smtp2web.tin.it ([212.216.176.236]) by relay1.thorcom.net with esmtp (Exim 4.89) (envelope-from ) id 1dH9d7-0004Vs-HU for rsgb_lf_group@blacksheep.org; Sat, 03 Jun 2017 15:02:15 +0100 Received: from feu20 (10.192.64.30) by smtp2web.tin.it (8.6.060.43) id 5822EBD203B22E6B for rsgb_lf_group@blacksheep.org; Sat, 3 Jun 2017 16:02:11 +0200 Received: from (80.182.160.35) by wmlighttin.pc.tim.it; Sat, 3 Jun 2017 16:02:11 +0200 Message-ID: <15c6e436e71.marcocadeddu@tin.it> Date: Sat, 3 Jun 2017 16:02:11 +0200 (CEST) From: "marcocadeddu@tin.it" To: Mime-Version: 1.0 X-Originating-IP: 80.182.160.35 X-Scan-Signature: 42a2731f53a2e4b860285fcdd7a3607b Subject: 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 v53ECidN017800 Status: O X-Status: X-Keywords: X-UID: 11862 Hi Alan, Andy, Chris, I replaced the caps in the output LC with WIMA FKP1, the 2 caps wich replaces the missing half of the bridge are still Cornell Dubillier 940C serie (rated at 9A @100kHz), so now all the caps are pulse rated but... I regret to admit it, nothing changed :-(( Power out increases from 10 to 30Vdc and at 40Vdc after a first pulse the power slowly decreases till a couple of watts.. Just to check another thing: being the coil of the guard circuit disconnected, I jointed the 2 coils together (they are wound on the same support) increasing so the inductance of the L (25T more). Of course I had to retune and now I need C in the range of 5000pF but this narrowed the 3dB bandwidth of the LC from abt 15kHz to abt 8kHz so is the Q increased! ... I should visit Decathlon and look for a fishing rod! your sincerely depressed IK1HSS ----Messaggio originale---- Da: alan.melia@btinternet.com Data: 2-giu-2017 15.58 A: Ogg: Re: LF: Re: I: Fw: For today the FETs survived... Hi Marco, I may well be wrong I was experimenting with 150W at 35V I measured 12 to 15A through the capacitors (from memory) .......the confirmation is that the change is permanent. I dont remember seeing any heating effects. Single ended Class E may be considerably different to H-bridge. The currents a lower power will be less, about 1.5A or so (??) I am not sure it that would produce damage, but you would certainly see it as the power increased. Good Luck with it Alan G3NYK ----- Original Message ----- From: To: Sent: Friday, June 02, 2017 2:00 PM Subject: R: LF: Re: I: Fw: For today the FETs survived... Hi Alan, and thanks for joining :-) it's hard to believe at this stage that is correct to speak of "high currents".. The PA is an half bridge like Andy's 700W but now I'm testing at low voltage: I see these problem trepassing the 30Vdc supply level (and power is about 15W).. Anyway will try with the "pulse rated caps" you suggested just in case my "low current" "low tension" ideas are wrong. 73 Marco ----Messaggio originale---- Da: alan.melia@btinternet.com Data: 2-giu-2017 14.36 A: Ogg: LF: Re: I: Fw: For today the FETs survived... Hi Marco I dont know where you are putting the caps but I am assuming they are passing a high RF corrent. I found that the old style (valve) high voltage caps in my Class E test rig changed capacitance permanently during and after a run (capacitance reduced). I assumed that the current was fusing the foil connection to the lead-out wires. When using "pulse rated" capacitors as used in SMPSUs I had no further capacitance change problems. The ones I have are RIFA PHE 428 2000v from RS Components. I think Farnell do a WIMA equivalent. Best Wishes Alan G3NYK ----- Original Message ----- From: To: Sent: Friday, June 02, 2017 1:06 PM Subject: R: Re: Re: Re: LF: Re: I: Fw: For today the FETs survived... now my thoughts are even more confused.... Hi Andy, me again.... after a long night of meditation, I remembered I had a bounch of old style mica capacitators 1000pF 1000V.. I put 9 of them in parallel to get the closer value to the 8800pF I had before. Of course the resonance moved a bit and now is on 134.5 kHz with 3dB bandwidth of 9 kHz (Q=15 I know is a bit to high..) so carried out some tests on 134 kHz (of course on the dummyload) all without guard circuit 1st test xfmr 7T/19T (Ae197mm² R50 mat T38): 2Wout @10Vdc; 6,5 Wout@20Vdc; 13,7Wout@30Vdc stable.. @40Vdc after a quick peak the power slowly goes down till below 1W! 2nd test I had still on hands the previous xfmr 5T/12T (Ae197mm² same core as 1st test) so was worth to make a trial... same trend :-( for Vdc> 30V after a first peak... it goes down. I had another core available with different material (N30, Ae 154mm² R58) so I prepared a new xfmr with this core 7T/14T: 1,4Wout@10Vdc; 4,6Wout@20Vdc; 9,2Wout@30Vdc .... at 40Vdc a short burst with almost 15Wout and then down down down... :-(((((( I noticed a difference in comparison to your project: you connected the + and - rails to ground via 10nF and here I used 100nF caps could it explain this behaviour? 73 Marco ----Messaggio originale---- Da: marcocadeddu@tin.it Data: 1-giu-2017 22.20 A: Ogg: R: Re: Re: Re: LF: Re: I: Fw: For today the FETs survived... that was also my thought.. but they run at room temperature: the resonance is obtained with 4 polyesther 2200 pF 2000 Vdc caps. the classic boxes 25x15x5mm Marco ---- Messaggio originale---- Da: andy.g4jnt@gmail.com Data: 1-giu-2017 22.03 A: Ogg: Re: Re: Re: LF: Re: I: Fw: For today the FETs survived... If the conditions change as the PA is operating, it looks like capacitors heating up and changing its value. I can't think of any other component that will change with dissipation / heating. What type of capacitor are you using in the tank? Andy On 1 June 2017 at 19:59, marcocadeddu@tin.it wrote: > anybody has good ideas for a replacement hobby?? fishing? growing > flowers? > > Andy: the suggestion of try without the guard circuit revealed that > some effects in this area are present. > > I left the guard coil in place (I'm a bit lazy...) and disconnected > simply the 2 wires from the rectifier bridge. > The output improve of about 4dB with Vdd from 10 to 30V, the output is > stable up to 20Vdd, on 30V it show a peak of 16W, then the output > starts to decrease till a couple of watts :-( this happens also at 40 > and 50V. > The resonance of the output LC (with the guard coil open) shifts from > 137 to 140 kHz and the bandwidth decreases from 20kHz to 10 kHz. > > I need a long weekend of meditation... > 73 Marco IK1HSS > > > ----Messaggio originale---- > Da: marcocadeddu@tin.it > Data: 31-mag-2017 21.05 > A: > Ogg: R: Re: Re: LF: Re: I: Fw: For today the FETs survived... > > Andy.. you are almost better than online help desks :-D > > yes the guard circuit is on place but no current is flowing toward the > PA, testing disconnetting it needs just to warm up the iron ;-) > > the PS should > provide enough juice for 1200W input and the IRF460A are rated for 20A > @ 25°C (13A @ 100°C) so.. I admit it would like to give a try ;-) > > I don't guess the core is saturating specially at this power level > where rms is only 22V, the core is 50mm OD and has 195,7 mm²Ae: if I > am > not totally wrong B should be < 0,03T @50V with 7 turns on the primary > > Will tru to disconnect the guard circuit just in case the squirrel is > running in its cage ;-) > > Thanks again for assistence > > Marco IK1HSS > > > > ----Messaggio originale---- > Da: andy.g4jnt@gmail.com > Data: 31-mag-2017 20.39 > A: > Cc: > Ogg: Re: Re: LF: Re: I: Fw: For today the FETs survived... > > 7:19 turns (assuming 50R output) means you have a load resistance of > 6.8 > ohms which for 180V DC (81 V RSM fund sine) is nearly 1kW I don't > think > you really mean to go that extreme do you? 13 ohms is more > realistic. > > As for the tank resonance changing as power increases, that is very > wrong. > I wonder if the transformer is saturating. Not sure of your core Ae, > but > lets assume 200mm square, a core of about 16mm diameter. > > V = 4.44.F.N.A.B Plugging in 137kHz 7 turns, 200 mm^2 and a Bmax of > 0.1 > that suggests 85V RMS. > Which is exactlyly what you have. I suggest more primary turns . > Before > a transformer ratio of 1:2 was suggested, for Rload = 13 ohms > > Is the guard circuit in place ? Don't forget, it has to be > customised > to > you exact currents and coil Q. Get teh PA operating to its proper > settings > foirst - that you can do at low voltage power, it scales perfectly. > Only > when it it working properly can you add and set up the guard circuit. > > When I did teh 700W PA, I had a complete workign (albeit unreliable) > unit > before even thinking of teh guard circuitry. > > Andy > > > > > > On 31 May 2017 at 18:50, marcocadeddu@tin.it > wrote: > > > Hi Andy... me again... > > > > I was so curious to see what could happen thatI had a very quick > > dinner and connected all, but... > > > > now the output xfmr has 7T/19T here my > > readings/calculations: > > (see attached picture) > > again the power increase from 10 to 30Vcc then from 30 to 50Vcc after > > an initial burst it start to fall down.. > > I checked also the resonance of the LC: till 30Vcc is tuned on 137 > kHz > > with a 3dB bandwidth of 20 kHz, when I move to 40 and 50Vcc the > > "maximum" output shifts to 165 kHz... > > > > mumble mumble > > > > I tempted to have roasted FETs for dessert and see what happens at > > 180V! > > > > Marco, IK1HSS > > > > > > ----Messaggio originale---- > > Da: andy.g4jnt@gmail.com > > Data: 30-mag-2017 23.50 > > A: > > Cc: > > Ogg: Re: LF: Re: I: Fw: For today the FETs survived... > > > > I've just looked again at the circuit diagram you sent - on there the > > values are different from your statement in the email. It shows > > primary 5 > > turns, secondary 12 turns so a load resistance in the order of 9 ohms > > which > > is rather low if you are intending a Vdd of 180V - but closer to the > > ideal > > Rl > > > > The tank components have a reactance of 130 ohms which is too high a > Q > > is > > used with that 9 ohms Rload, You should be aiming for a Q in the > region > > of > > 6. > > > > Even with the optimum load R of 13 ohms described last time for 500 > > Watts > > from 180V rail the resulting Q of 10 is a bit too high - you will end > > up > > with high voltage and critical tuning > > > > Andy G4JNT > > > > On 29 May 2017 at 19:07, Andy Talbot wrote: > > > > > Yes. > > > As you'll see in my original write up, I originally forgot that the > > peak > > > of the fundamental sine component of a square wave is GREATER than > > the peak > > > by a factor of 4 / pi and initially my PA delivered a lot more > power > > (1.6 > > > times) than it was supposed to. > > > > > > So if the square wave has a peak value of 1, its fundamental sine > > > component has a peak value of 4/pi or around 1.27. The RMS of the > > > resulting sine is SQRT(2) less than this giving a Peak square to > RMS- > > sine > > > ratio of 0.9.. If you specifye peak-peak of the square wave, a > > further > > > factor of 2 applies, leading to the 0.45 ratio described before. > > > > > > Incidentally, this same ratio appears in that equation for flux > in > a > > > magnetic code, V = 4.44.F.N.A.B > > > The magic number 4.44 is actually SQRT(2) * pi and comes about > > from > > > the same sort of sine to square transform. > > > > > > Andy > > > > > > On 29 May 2017 at 18:48, marcocadeddu@tin.it > > wrote: > > > > > >> > > >> uhuh... a slightly silly misleading assumption... Vdc are the same > > of > > >> Vrms before FETs make their work! > > >> > > >> Thank you Andy for pointing out it!! > > >> With this approach calculation changes a bit and probably with the > > >> right Xfmr the PA can give higher satisfaction :-) > > >> > > >> Hopefully the FETs will survive and this time I'm ready to burnout > > the > > >> antenna hi > > >> > > >> Will keep you both updated, thank you once more Andy > > >> > > >> 73 Marco, IK1HSS > > >> ----Messaggio originale---- > > >> Da: andy.g4jnt@gmail.com > > >> Data: 28-mag-2017 21.18 > > >> A: "marcocadeddu@tin.it", > > >> > > >> Cc: > > >> Ogg: LF: Re: I: Fw: For today the FETs survived... > > >> > > >> First thing I noticed is that your turns ratio on the output > > >> transformer > > >> doesn't look right. > > >> You quote "* ... with primary winding of 15 turns and secondary of > > 12 > > >> turns...*" > > >> > > >> 180V DC in a half bridge is 180V peak-peak square wave. > > >> The fundamental sine part of that is 4/pi * 180 = 229V pk-pk > > >> so is 229V /[2.SQRT(2)] = 81V RMS > > >> > > >> To a good approximation RMS(fund) from a half bridge is Vrms > (fund) > = > > >> 0.45VDC > > >> > > >> For 500 Watts out, Rload = 81 ^ 2 / 500 = 13 ohms > > >> > > >> So to match to 50 ohms you need a turns ratio of SQRT(50/13) = > 1.9: > > >> 1 so > > >> call it 2:1 Keeping 12 turns on the secondary means you need 6 > > turns > > >> on > > >> the primary > > >> > > >> When operating at reduced voltage, the power out will vary exactly > > as > > >> the > > >> square of the voltage. > > >> Recalculating from first principles for a 12V supply: > > >> > > >> 12V DC = 12V pk-pk = 12 / [2.SQRT(2)] * 4/pi = 5.4V RMS > > (fundamental) > > >> in 13 ohms should give 5.4^2/13 = 2.2 Watts > > >> > > >> check using ratio of voltages, squared : > > >> > > >> (12V/180V) ^ 2 * 500W = 2.2 Watts which is the same as above. > > >> QED > > >> > > >> Your 15:12 ratio result sin a load impedance of (15/12)^2 * 50 = > 78 > > >> ohms > > >> > > >> At 40V DC == 18V RMS(fund) that will give 18^2/78 = 4.1 watts > which > > is > > >> actually LESS that you are seeing - the 2* discrepancy is odd, but > > the > > >> low > > >> power is in the area of what you measured.. > > >> > > >> Andy G4JNT > > >> > > >> > > >> > > >> On 28 May 2017 at 19:34, marcocadeddu@tin.it > > >> wrote: > > >> > > >> > Hi Chris, > > >> > > > >> > I tried to post this message on the reflector but apparently I > had > > no > > >> > success.. > > >> > As promised I keep you updated but as you can read in the > > >> > attachment the first trials were not enocouraging... > > >> > Andy, may I ask you to read my report? your interpretation and > > >> > suggestion are welcome! > > >> > > > >> > 73, Marco IK1HSS > > >> > > > >> > > > >> > -----Original message----- > > >> > > > >> > From: "marcocadeddu@tin.it" marcocadeddu@tin.it > > >> > Date: Sun, 28 May 2017 17:01:33 +0200 > > >> > To: rsgb_lf_group@blacksheep.org > > >> > Subject: For today the FETs survived... > > >> > > > >> > Hi LF, > > >> > > > >> > hope that also the toroids of Chris survived! > > >> > My FETs survived, but they are not working as expected :-( > > >> > Attached the report on my attempt to duplicate the half bridge > of > > >> > Andy.. > > >> > Has anyone suggestions before I try to cook all connecting to > the > > >> > 180Vdc supply? > > >> > > > >> > Thank you > > >> > 73 Marco IK1HSS > > >> > > > >> > > > >> > -- > > >> > This message has been scanned by E.F.A. Project and is believed > to > > be > > >> > clean. > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > ---------- Forwarded message ---------- > > >> > From: "marcocadeddu@tin.it" > > >> > To: > > >> > Cc: > > >> > Bcc: > > >> > Date: Sun, 28 May 2017 17:01:33 +0200 (CEST) > > >> > Subject: For today the FETs survived... > > >> > Hi LF, > > >> > > > >> > hope that also the toroids of Chris survived! > > >> > My FETs survived, but they are not working as expected :-( > > >> > Attached the report on my attempt to duplicate the half bridge > of > > >> > Andy.. > > >> > Has anyone suggestions before I try to cook all connecting to > the > > >> > 180Vdc supply? > > >> > > > >> > Thank you > > >> > 73 Marco IK1HSS > > >> > > > >> > > > >> > -- > > >> > This message has been scanned by E.F.A. Project and is believed > to > > be > > >> > clean. > > >> > > > >> > > > >> > > > >> > > > >> > > >> > > >> > > >> > > >> > > > > > > > > > > > > > > > > > >