Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w39I3Yxv022703 for ; Mon, 9 Apr 2018 20:03:35 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1f5b3m-0003bH-OA for rs_out_1@blacksheep.org; Mon, 09 Apr 2018 18:58:30 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1f5b3c-0003b8-EU for rsgb_lf_group@blacksheep.org; Mon, 09 Apr 2018 18:58:20 +0100 Received: from resqmta-ch2-12v.sys.comcast.net ([69.252.207.44]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1f5b3Z-00088V-9o for rsgb_lf_group@blacksheep.org; Mon, 09 Apr 2018 18:58:19 +0100 Received: from resomta-ch2-12v.sys.comcast.net ([69.252.207.108]) by resqmta-ch2-12v.sys.comcast.net with ESMTP id 5b1LfbEac3HAQ5b1bfyAN4; Mon, 09 Apr 2018 17:56:15 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1523296575; bh=83BU5ZhWKZN6VlUMtwfwG0Sav7+RxfplbcgVLE+tyE8=; h=Received:Received:Message-ID:From:To:Subject:Date:MIME-Version: Content-Type; b=IVUqpMqDDTs2J/S09DtCD1LEUAK2gfpwM8kpElCnxEgkY+P1h6o3baZ9wFZjb2PwX oUz5JNaXfiF9voiD1qpI+mvQ5LqmLEpKURFTTODCMfLPbWzx6wB0fMizm0HmNXBUSr B2pZBdyIN4RY4M5YLpeeFNjiuhtJFpbw2Heq0iUJUmucacohP1OSDREB+Qboi678h+ jozqNlK+cfJSzw25nNPsX3C5h6orPh6u/l/sufdf5O8rrHu5RJ6BfaA5/il/LuU2QE LkPt8XD5GwvdBpc7+N72FjWguLrtahna517B0DrKwaN/QzoXIIMu2Tvf8MMFcJq6/8 5esSc9D0bpUVw== Received: from DELL4 ([73.4.253.141]) by resomta-ch2-12v.sys.comcast.net with SMTP id 5b1ZfcOedKKpS5b1afT0Ia; Mon, 09 Apr 2018 17:56:15 +0000 Message-ID: <1158B03EED994922A8AA816DB276B343@DELL4> From: To: References: <162a4797468-1db9-bdf2@webjas-vae168.srv.aolmail.net> <1UQROqZht1.1c1VdzC0S69@optiplex980-pc> <3a0c0669-018b-13a7-b56b-dd3f63fab464@n1bug.com> <197556217.20180409124931@gmail.com> <37574432-b72e-f2d1-0e85-af19dd970817@n1bug.com> <4D19B3707137430CBE04857FBA5C80B1@gnat> <1b882ae9-fede-3ec4-256e-9b068d3acf99@n1bug.com> <1539CCA16B9A4092972CB000BE4C440A@DELL4> Date: Mon, 9 Apr 2018 13:56:14 -0400 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 X-CMAE-Envelope: MS4wfAWQ8uWdep+WJwTjXHpVyMltoeN3wbo7rNRnJ4lLEXxkOciIeH0lCYkoF4WUpAKa+ZUHcyuBwlNeGhCEbJg3LFfrvCXTh41eSGCcDIQzRUxoFc0+NONW jM5kX2jKWfN1nz1+p8e6HFmj6IgNPeaeKZu5mq77GkquApBTz+kDIVDV X-Spam-Score: 0.8 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Paul One other quick observation ... the leads of the thick film snubber resistors that go to ground are rather long. It's probably not visible in the photo of mine, but the milled circuit board 'pocket' has the copper ground plane close to the body of the resistor. Try sticking a small piece of circuit board or copper strap in there to make a wide connection to the ground plane. May not matter much ... but we're trying to eliminate all possibile problems. [...] Content analysis details: (0.8 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (jrusgrove[at]comcast.net) 0.1 URIBL_SBL_A Contains URL's A record listed in the Spamhaus SBL blocklist [URIs: n1bug.com] 0.6 URIBL_SBL Contains an URL's NS IP listed in the Spamhaus SBL blocklist [URIs: n1bug.com] 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: b4085bc26841e34d79a2f3beb8f287b1 Subject: Re: LF: W1VD amp help - more waveforms Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=response Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.9 required=5.0 tests=FORGED_MUA_OUTLOOK, NO_REAL_NAME 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 Paul One other quick observation ... the leads of the thick film snubber resistors that go to ground are rather long. It's probably not visible in the photo of mine, but the milled circuit board 'pocket' has the copper ground plane close to the body of the resistor. Try sticking a small piece of circuit board or copper strap in there to make a wide connection to the ground plane. May not matter much ... but we're trying to eliminate all possibile problems. Jay W1VD ----- Original Message ----- From: To: Sent: Monday, April 09, 2018 1:41 PM Subject: Re: LF: W1VD amp help - more waveforms > Paul > > Thanks for the photos and information. I was more interested in the superimposed gate waveforms > than the drains, though. A pix of the LPF as well would be appreciated ... think there was one > last week. Just for the record ... my doubler was never mounted inside the amplifier ... so you > are covering new ground with that. I would think having it external to the amplifier would be less > problematic. For testing, stick to driving it with the HP3325A for now ... which is what you're > most likely already doing. > > Can't find much fault with the construction ... other than the somewhat loose primary winding on > the transformer. In mine, the primary winding was nestled inbetween the turns of the secondary. > This is important to minimize leakage reactance ... which also contributes to excessive ringing. > > Think I would continue to concentrate on getting the ringing down before going to high power. > > One other thing ... have you double checked that you have the correct capacitance in the LPF? > > Jay W1VD > > > > > > > ----- Original Message ----- > From: "N1BUG" > To: > Sent: Monday, April 09, 2018 11:34 AM > Subject: Re: LF: W1VD amp help - more waveforms > > >> Yep, voltage breakdown of the FETs was my worry. However I may be >> making a false assumption. I assumed the voltage spikes in the >> ringing would vary linearly with applied drain voltage? Perhaps that >> isn't necessarily so? >> >> With 13V on the drains the first spike here is 'about' 64V. >> >> Efficiency seems fine. I wouldn't try to put an exact figure to it >> what with measurement accuracy in three places (voltage, current, RF >> power) but it 'appears' to be in the mid 90s. >> >> Paul >> >> >> On 04/09/2018 11:02 AM, jrusgrove@comcast.net wrote: >>> Alan >>> >>> The main concern about the ringing is that the positive extreme stays below the drain source >>> breakdown voltage ... with some 'headroom'. Otherwise ... >>> >>> Jay W1VD >>> >>> >>> ----- Original Message ----- >>> From: "Alan Melia" >>> To: >>> Sent: Monday, April 09, 2018 10:21 AM >>> Subject: Re: LF: W1VD amp help - more waveforms >>> >>> >>>> Paul >>>> I think you need to step back from this a little. One point, design/cable routing at 137kHz is >>>> normally not that critical and it is unlikely it is having much effect. Many us have >>>> ''haywired'' >>>> PAs at these frequencies without major troubles....even using croc-leads!! >>>> >>>> You are unhappy about the drain waveforms.......why?? the ringing is on the ''off'' device and >>>> so >>>> doesnt really matter in terms of efficiency. Consider what is happening. The FET drive goes off >>>> and the drain current starts to drop inductance in the drain feed causes the voltage to rise to >>>> try to keep the current flowing. Then on top of this the other transistor switches on and the >>>> transformer connection for the off side sees a rising induced voltage out of the transformer. >>>> There is bound to be overshoot but it does not absorb much power. It may be the generous ''dead >>>> zone'' (whilst a good idea) that is producing this picture. >>>> >>>> The critical part is the the flat zero volt line when the FET is on. The current pulse rings a >>>> bit, but the current drops in the second half of the pulse.....why?? This, I think, is really >>>> the >>>> loss of power. Does Jay's show this? The point I am making is don't get drawn up blind alleys >>>> because a trace just does not look ''pretty''. >>>> >>>> I think we have mentioned this before but the transient performance of the power supply may be >>>> a >>>> factor. There should not be great changes in the current draw because you are switching the PSU >>>> load from one transistor to the other but there can be higher speed transients that can affect >>>> power supply regulators in unexpected ways. >>>> >>>> As Andy said efficiency at 12v is not very meaningful because of the high rds of these FETs. It >>>> is >>>> usefull to run up a PA at low volts say for safety when the antenna needs to be tuned. >>>> >>>> Finally the scope probes are placing an. albeit small, capacitance across the drains (I am >>>> assuming they are correctly trimmed) The waveform can often be affected by where the ground is >>>> picked up from. >>>> >>>> Stick with it because you are close to being ''there'' >>>> >>>> Alan >>>> G3NYK >> > >