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=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 v559Nnvl026334 for ; Mon, 5 Jun 2017 11:23:50 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dHo9P-0003GZ-Qx for rs_out_1@blacksheep.org; Mon, 05 Jun 2017 10:18:15 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dHo9O-0003GQ-Ar for rsgb_lf_group@blacksheep.org; Mon, 05 Jun 2017 10:18:14 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dHo9K-00032p-G4 for rsgb_lf_group@blacksheep.org; Mon, 05 Jun 2017 10:18:13 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id A81B720CAA for ; Mon, 5 Jun 2017 11:18:06 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3wh8P94zHNzysV for ; Mon, 5 Jun 2017 11:18:05 +0200 (CEST) Message-ID: <593521CC.9070703@posteo.de> Date: Mon, 05 Jun 2017 11:18:04 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <15c6e6a8ba3.marcocadeddu@tin.it> In-Reply-To: <15c6e6a8ba3.marcocadeddu@tin.it> X-Scan-Signature: 9e3996b06e6d670e8814874478dd0b45 Subject: Re: R: Re: R: Re: LF: Re: I: Fw: For today the FETs survived... Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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 Status: RO X-Status: X-Keywords: X-UID: 11895 Hello Marco, I was unable to write a longer text for a few days (no desktop PC available, just the smartphone and Teamviewer) so my answer is a bit late. You've got a lot of advice since that time. I'm just adding what came to my mind... -I assume you already checked that the supply voltages stay constand in any working point. -The gate voltages are important. Also the duty cycle should be constant and close to 50% for best operation. In my H bridge PA for 137 kHz the gate voltage is +- 8V, quite a rectangular waveform. Unfortunately i have no scope captures quickly available. -Try to lower the 4 Ohm resistor after the IDXX driver. It is there to avoid oscillations after the switching slopes. Maybe 2 Ohm is enough. -Even more important: Make sure the transformer is wound for a minimum stray inductance because this will quickly lead to strong oscillations. Wind all the 3 windings equally spread arround the whole core (ferrite, e.g. N30, AL>2000nH). Wind them trifilar, not separated. If there are still problems show us images of: The gate source voltage, the gate drive transformer. 73, Stefan Am 03.06.2017 16:44, schrieb marcocadeddu@tin.it: > Hi Stefan, > > and thank you :-) so you have too something to mumble while sending > VLF SMS ;-) > There is nothing really new.. I started from an avalable > chassis with on board a PS giving 180Vdc (1200W) and assembled the > Andy's half bridge 700W switching PA and before give it the full power > I'm checking with lower DC supply. Attached you see the schematic with > some change at the moment.. > The output xfmr has 7T/19T, the coil of the guard circuit is not > connected (now is in serie with L2) and the resonating caps now are > 5x1000pF in parallel. > The aim is finally with 180Vdc of supply have an output of 0,5÷1kW > but.... as you probably red in the previous messages, from 10 to 30Vdc > the PA runs, at low power of course (up to 15W), and complies the > calculations; with supply between 30 and 50 Vdc the output go down to a > couple of W. > I made several trials it the last days, changing the core of the xfmr, > the turn ratio, the kind of capacitators but nothing changes (or at > least the change are within a fraction of dB). > > that's the sad history Stefan... > All thoughts and suggestions are welcome! (including go to fish ;-)) ) > Marco > > ----Messaggio originale---- > Da: selberdenken@posteo.de > Data: 3-giu-2017 16.19 > A: > Ogg: Re: R: Re: LF: Re: I: Fw: For today the FETs survived... > > Hi Marco, > > If you like, i can help you. Just need a schematic to see what you > want > to do. Targer power, voltage, etc... > > 73, Stefan > > Am 03.06.2017 16:02, schrieb marcocadeddu@tin.it: > >> 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>>>> >>>>> >> 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>>>>> >>>>>> >> 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. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> > > >