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 w9BKfmSY031400 for ; Thu, 11 Oct 2018 22:41:50 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gAhh9-0004lQ-4U for rs_out_1@blacksheep.org; Thu, 11 Oct 2018 21:36:31 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gAhh1-0004lH-Mr for rsgb_lf_group@blacksheep.org; Thu, 11 Oct 2018 21:36:23 +0100 Received: from mail-qt1-x830.google.com ([2607:f8b0:4864:20::830]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1gAhgy-0002J9-FN for rsgb_lf_group@blacksheep.org; Thu, 11 Oct 2018 21:36:22 +0100 Received: by mail-qt1-x830.google.com with SMTP id e22-v6so11521532qto.6 for ; Thu, 11 Oct 2018 13:36:19 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=ITjfQBTex1tz4hr3jYyPlcp5rcu4jbYqVvoRbMqtv28=; b=L5x6j8nBUtsY4JG/CZlOAPHnynrZ/ATvwEF/wCeim1XZizwuawQXGtUEaHashuc5Ia GS7kO+2Jy2WVdU8MH4NxNBf+y1tYzPYnonYXgMbwGKXWKwwxWauGTIcGj0XaUbLkUvfK 9z03O1i8HgZOi0FA4Dz8l6vLVOnZyXgF+C5nxsSjpxOCtbaR3UJL086WgoImTmBn93sc wZyahsbc5yZVP6mkeiHL3oWUzIUBNC+UrRg7f4P76ZZ9fkLxzRSsiMr5aJp+Dmk0khcg Q57vNVOqXflSzcPLroHyllOGOq0KV0YMfVrUP4L8+kY+E1Y921gP49SukgqW3ggVqk3z UEtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=ITjfQBTex1tz4hr3jYyPlcp5rcu4jbYqVvoRbMqtv28=; b=B6g/BJi8zubcRqLMnDy2ezq9NegQD9WQJtrSg5VK370XbIAXzpldle4Ee6tpQ0D1A7 LnHJQ0/OISqD70+H02jtzXMu1YUfSBX0fwzHpMA7H8HtDD8AsAOk7i6ttTw5xgIwxNIz rnxrtBQw7HNYvSqC7gtj6D85eZGz3bKdzRC3Hzb6bCHsiQkF42fqgt/dQmdxwYxMnKs4 1GOla3JA3/VA2E5WQIp6zLHr0xWdd7IA8WEFuoOfxI4Vbd/w/vPokR9j2hMItUlDz530 WJHGUdCsZ6O7NjTS0Fj+e01p7gFNtMMk/o0178/8XBpkt7ETRS84DmKZnV9V2a8CCUgh tLRA== X-Gm-Message-State: ABuFfogVXxX7xBJTepm47jFEHq625ozeIOzUfvPlKDEIXaGQ/vNYtS/d KaSQ04hrM4kh12eULhrFBrPEyZXvGxPXssSYkPmfEQ== X-Google-Smtp-Source: ACcGV60N+XnyuM8r/sLqlFaKM5LQukFX1dB/2XgAlOhM0rku5srQt0tKB7TteUSoLXU+4eg914yDeJ3jLkXyPmpp7vc= X-Received: by 2002:aed:252e:: with SMTP id v43-v6mr3081754qtc.211.1539290178151; Thu, 11 Oct 2018 13:36:18 -0700 (PDT) MIME-Version: 1.0 References: <1585153745.20181010151550@gmail.com> In-Reply-To: <1585153745.20181010151550@gmail.com> From: David Bowman Date: Thu, 11 Oct 2018 20:36:03 +0000 Message-ID: To: rsgb_lf_group@blacksheep.org X-Spam-Score: 1.0 (+) 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 @@CONTACT_ADDRESS@@ for details. Content preview: Hi Chris. Not sure I have a solution for the circuit you have. However, it may be worth not using the 180 degree outputs from the Silab oscillator. Have you thought about the advantages of a FET driver that has a common input but 2 antiphase outputs ?? The TC4428 is an example. They take great care with rise times and propagation delays....perhaps the Si device does not give 'perfect' waveforms. [...] Content analysis details: (1.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:830 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (davidg0mrf[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid 1.0 FREEMAIL_REPLY From and body contain different freemails X-Scan-Signature: 6ae5fe68d6708d1e4a9cbdf0f0af43e5 Subject: Re: LF: FET driver driven direct from a Si5351a questions Content-Type: multipart/alternative; boundary="0000000000004669b40577f9ec70" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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 --0000000000004669b40577f9ec70 Content-Type: text/plain; charset="UTF-8" Hi Chris. Not sure I have a solution for the circuit you have. However, it may be worth not using the 180 degree outputs from the Silab oscillator. Have you thought about the advantages of a FET driver that has a common input but 2 antiphase outputs ?? The TC4428 is an example. They take great care with rise times and propagation delays....perhaps the Si device does not give 'perfect' waveforms. Worth a try ?? regards David On Wed, Oct 10, 2018 at 2:23 PM Chris Wilson wrote: > > > Hello LF'ers, > > Hi, bit of an oddball problem here (again.... ;)) I have > a 1kW Class D low frequency 137 kHz LF ham band amp I built. It has > worked fine for many months. I like experimenting / > learning /simplifying so when the designer of the QRP Labs U3S exciter > I am using added some new firmware features I decided to try and take > advantage of it. The U3S is based around a SiLabs Si5351a synthesizer > chip. Originally I had the U3S send out a X2 frequency from CLK0 alone > as the amp, a Class D device, halved it. (None of the circuitry after > the CLK0 and CLK1 outputs in the U3S is used, the Si chip *IS* the > exciter with no amplification as shown on the U3S schematic from the > BS170(s), in fact these components are not even fitted). > > The new firmware allowed me to delete one IC (the 74F74) and the 5V > regulator and drive the FET driver IC at X1 frequency with the > outputs from CLK0 and CLK1 of the Si5351a set to be 180 degrees out > of phase. Before this firmware feature addition I used just CLK0 at > X2 and the 74F74 IC did the division and phasing and its output drove > an IR2110 FET driver IC. I swapped to an MCP1404 driver IC so I could > delete the 5V regulator as well. > > What is happening is with no voltage to the amp's FET drains the gate > waveform is excellent. but as soon as even 5V is applied to the drains > the gate waveform goes ragged and drain waveforms go HORRENDOULSY > spiky. > > With the original setup the gate and drain waveforms (gates at the > bottom) look fine to me: > > http://www.chriswilson.tv/inverted/good-gate-and-drain-waveforms.jpg > > I also see seemingly random ultra short duration drop outs in > the square waves from CLK0 and CLK1. These ultra brief glitches occur > on CLK0 and CLK1 even when nothing is connected to them save my X10 > scope probes. This suggests a firmware issue to me, but I may be > missing something like impedance matching? This is also apparent > whilst it is transmitting the digital mode WSPR from the U3S. Can > anyone think of a reason for this please? > > It may be that the very infrequently used firmware option to have the > Si5351a output on both CLK0 and CLK1 with a 180 degree phase shift is > buggy, in which case I am solely at the mercy of the designer, but I > want to be sure I am not missing anything before assuming this to be > the case. I have also been told that it may be that the Si5351a > produces less than perfect waveforms below about 3 MHz when the > outputs are inverted, but no source for that was cited. So the changes > from working perfectly to problematic are using a 180 degree phase > shift from both CLK0 and CLK1 adding two 82k resistors to the 12V rail > to bias the input pins of the MCP1404, and using the MCP1404 instead > of the IR2110 which needed a 5V supply as well as 12V. > > If you are still with me, thank you! > > http://www.chriswilson.tv/inverted/amp-less-surplus-controls.jpg > > http://www.chriswilson.tv/inverted/amp-simplified6.jpg > > http://www.chriswilson.tv/inverted/u3s-schematic.jpg > > http://www.chriswilson.tv/inverted/no-drain-voltage.jpg > > http://www.chriswilson.tv/inverted/with-drain-voltage.jpg > > > > -- > Best regards, > Chris mailto:dead.fets@gmail.com > > > --0000000000004669b40577f9ec70 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi Chris.
Not sure I have a solution for th= e circuit you have.=C2=A0
However, it may be worth not using= the 180 degree outputs from the Silab oscillator.=C2=A0 Have you thought a= bout the advantages of a FET driver
that has a common input but 2= antiphase outputs ??
The TC4428 is an example. They take great c= are with rise times and propagation delays....perhaps the Si device does no= t give 'perfect' waveforms.

Worth a try ??=

regards

David
<= /div>
On Wed, Oct 10, 2018 a= t 2:23 PM Chris Wilson <dead.fets= @gmail.com> wrote:


Hello LF'ers,

Hi, bit of an oddball problem here (again.... ;)) I have
a 1kW Class D low frequency 137 kHz LF ham band amp I built. It has
worked fine for many months. I like experimenting /
learning /simplifying so when the designer of the QRP Labs U3S exciter
I am using added some new firmware features I decided to try and take
advantage of it. The U3S is based around a SiLabs Si5351a synthesizer
chip. Originally I had the U3S send out a X2 frequency from CLK0 alone
as the amp, a Class D device, halved it. (None of the circuitry after
the CLK0 and CLK1 outputs in the U3S is used, the Si chip *IS* the
exciter with no amplification as shown on the U3S schematic from the
BS170(s), in fact these components are not even fitted).

=C2=A0The new firmware allowed me to delete one IC (the 74F74) and the 5V =C2=A0regulator and drive the FET driver IC at X1 frequency with the
=C2=A0outputs from CLK0 and CLK1 of the Si5351a set to be 180 degrees out =C2=A0of phase. Before this firmware feature addition I used just CLK0 at =C2=A0X2 and the 74F74 IC did the division and phasing and its output drove=
=C2=A0an IR2110 FET driver IC. I swapped to an MCP1404 driver IC so I could=
=C2=A0delete the 5V regulator as well.

What is happening is with no voltage to the amp's FET drains the gate waveform is excellent. but as soon as even 5V is applied to the drains
the gate waveform goes ragged and drain waveforms go HORRENDOULSY
spiky.

With=C2=A0 the=C2=A0 original=C2=A0 setup=C2=A0 the gate and drain waveform= s (gates at the
bottom) look fine to me:

http://www.chriswilson.tv/invert= ed/good-gate-and-drain-waveforms.jpg

I also see seemingly random ultra short duration drop outs in
the square waves from CLK0 and CLK1. These ultra brief glitches occur
on CLK0 and CLK1 even when nothing is connected to them save my X10
scope probes. This suggests a firmware issue to me, but I may be
missing something like impedance matching? This is also apparent
whilst it is transmitting the digital mode WSPR from the U3S. Can
anyone think of a reason for this please?

It may be that the very infrequently used firmware option to have the
Si5351a output on both CLK0 and CLK1 with a 180 degree phase shift is
buggy, in which case I am solely at the mercy of the designer, but I
want to be sure I am not missing anything before assuming this to be
the case. I have also been told that it may be that the Si5351a
produces less than perfect waveforms below about 3 MHz when the
outputs are inverted, but no source for that was cited. So the changes
from working perfectly to problematic are using a 180 degree phase
shift from both CLK0 and CLK1 adding two 82k resistors to the 12V rail
to bias the input pins of the MCP1404, and using the MCP1404 instead
of the IR2110 which needed a 5V supply as well as 12V.

If you are still with me, thank you!

http://www.chriswilson.tv/inverted/a= mp-less-surplus-controls.jpg

http://www.chriswilson.tv/inverted/amp-simplif= ied6.jpg

http://www.chriswilson.tv/inverted/u3s-schematic= .jpg

http://www.chriswilson.tv/inverted/no-drain-v= oltage.jpg

http://www.chriswilson.tv/inverted/with-d= rain-voltage.jpg



--
Best regards,
=C2=A0Chris=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 mailto:dead.fets@gmail.com


--0000000000004669b40577f9ec70--