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 w8TAQQJ0001486 for ; Sat, 29 Sep 2018 12:26:29 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1g6CPH-0005on-Ce for rs_out_1@blacksheep.org; Sat, 29 Sep 2018 11:23:27 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1g6CPG-0005oe-Ss for rsgb_lf_group@blacksheep.org; Sat, 29 Sep 2018 11:23:26 +0100 Received: from mail-ed1-x531.google.com ([2a00:1450:4864:20::531]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1g6CPE-0006Ah-P1 for rsgb_lf_group@blacksheep.org; Sat, 29 Sep 2018 11:23:25 +0100 Received: by mail-ed1-x531.google.com with SMTP id c1-v6so999635ede.5 for ; Sat, 29 Sep 2018 03:23:24 -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=CEDtww9TNGLelXZMP2YfMW4xiaEgFV+rgUdpXVQSyR4=; b=Sa+W6ry22pV50dWLiStoV4gZZ79/lM076mEyPLgkbZNb+rzTdin+rlVrAkzNeHhqsS SZ7IyEfcjNOte6XvyEDi+GQ323NlxkfM7Qb7NRyr6befw6DDLm9Jp3CSz7T5pSZOvfbB FajsMkHH9/3WRV2EHbmJoUOuyE35p6IBB8lt75F1rXfPv8pC5OZ3r35J5TND7j0DOAar ZZTbycUlMIdV289uBer6gh49tgwK1+oX5PPyF3lsOjqkAFIg9PC2iDeSOHl36KduHPA5 BgPjS10YmOCHDo83EJEVqIoxS90vbYKdxVgwRQR9hu9iQ60vUkjlixpHcNi8UzhDUKUp V4VQ== 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=CEDtww9TNGLelXZMP2YfMW4xiaEgFV+rgUdpXVQSyR4=; b=aawalqXhwd2m52s7GoFcCptoGeBcE/tvJOD1pAc9ppoLhfyk4T9X5Q20yGQqvQq6SD fBX+8cWhEjMRe+5sVJmT/Z1ymiVCWDd/eWcznVTvkO63BcZDnzaq4F2Sb9WNmQ4PrSe7 0GZpfO2jGeXIf0MnL/8l6k13X8Xi29bb9pi+OhKXmFVusToPQ4fTozbv4xQQwr8lyDG7 XKZUFooTESh0eBeIlCeuWdQXRSVWU/lmKy/ccRcayiSaCW9PXNfeBlT3nGsQEib4j79l 3YJl2xGYTtd6Hlobil51pdiUh5RymyhqMTGNuwMfSzn+N6dmOfMT8ADb9J2mhdjm36eH AlMg== X-Gm-Message-State: ABuFfoiP6QlFHg4HDUZajUheSgj87c5lOjVorpep/tdvCI9mY9OT9MP6 rxNaUFV8VOkg6qJVTiK0qKba7+UNyFJMhJLJlKD8TQ== X-Google-Smtp-Source: ACcGV61QAEukSUgcXCx35GRyTL5DWQBCykNODXO+/gbsE3FiV6CjRtcPdFTog9nHWba5I0rIlslalMCMs2g5/El79Uk= X-Received: by 2002:aa7:d5da:: with SMTP id d26-v6mr7919716eds.161.1538216603310; Sat, 29 Sep 2018 03:23:23 -0700 (PDT) MIME-Version: 1.0 References: <6DB8451D7F3D3947A5918808A59621EA08642503@servigilant.vigilant.local> <1491423438.20180929110637@gmail.com> In-Reply-To: <1491423438.20180929110637@gmail.com> From: Andy Talbot Date: Sat, 29 Sep 2018 11:23:12 +0100 Message-ID: To: LineOne 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: Partly, perhaps, but I suspect your dead FETs could be due to antenna reflections of wideband transients of a hard switched waveform. A sharp rise (or fall) time hitting a high Q antenna will cause it to ring. The resulting oscillations will most likely be out of phase with voltages present in the PA and could be causing over-voltage. The correct way to do on-off on a really high power switching PA is to key the PA itself - ideally with a ramped waveform [...] 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 [2a00:1450:4864:20:0:0:0:531 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[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: 09c1a181dc7b5fd4ce37590584a561d1 Subject: Re: LF: Signal bandwidth in Op32 LF Content-Type: multipart/alternative; boundary="0000000000003a5c450576fff6f0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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 --0000000000003a5c450576fff6f0 Content-Type: text/plain; charset="UTF-8" Partly, perhaps, but I suspect your dead FETs could be due to antenna reflections of wideband transients of a hard switched waveform. A sharp rise (or fall) time hitting a high Q antenna will cause it to ring. The resulting oscillations will most likely be out of phase with voltages present in the PA and could be causing over-voltage. The correct way to do on-off on a really high power switching PA is to key the PA itself - ideally with a ramped waveform WSPR uses phase continuous small frequency transistions, so the Hi-Q antenna sees nothing to make it 'ring' In the early days of 73kHz when people used 'Coherent', that was hard switched 10 Bit-per-second PSK some users reported damaged PAs. My loading coil certainly made clicking noises when the phase shifted, although the modified 100 Watts MOSFET audio amp (a linear PA) survived. Andy www.g4jnt.com On Sat, 29 Sep 2018 at 11:09, Chris Wilson wrote: > > > Hello Andy, > > Could this in any way supply a reason for me seeing the odd dead FET > when running OPERA and never when running WSPR? I always had the > feeling that the fact OPERA stops and starts so many times in 32 mode > that it was a cause of an occasional glitch that blew the FETS in my > Class D > amp... To be honest it's the main reason I rarely TX with OPERA on LF. > The amp is permanently powered, the exciter, normally my U3S then > stops and starts whatever mode is selected. With OPERA I think a FET > will usually go at the START of one of the TX cycles, not at the end. > > Thanks. 2E0ILY > > Saturday, September 29, 2018, 9:42:10 AM, you wrote: > > > If you stop and start a divider, the phase jumps about randomly. > > Each time you start the divider, its output signal starts up in a > > differnet phase to what it would have been if left running > > > > To achieve phase coherent, you must keep the divider running and gate > the OUTPUT separately > > > > This issue is a problem with beacons in general that employ FSK > > keying for their CW ident. If they adopted on-off keying, then > > long term integration cold take place though the keying cycle. But > > unfortunately, IARU (or whatever organisation that tries to mandate > > these things), appear to require FSK keying. SO most beacon keepers > > comply. (I don't, the Bell Hill microwave beacons, GB3SCx all use > on-off keying) > > Andy > > www.g4jnt.com > > > > > > -- > Best regards, > Chris mailto:dead.fets@gmail.com > > > --0000000000003a5c450576fff6f0 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Partly, perhaps, but I suspect your dea= d FETs could be due to antenna reflections of wideband transients of a hard= switched waveform.=C2=A0 A sharp rise (or fall) time hitting a high Q ante= nna will cause it to ring.=C2=A0 The resulting oscillations will most likel= y be out of phase with voltages present in the PA and could be causing over= -voltage.=C2=A0 =C2=A0The correct way to do on-off on a really high power s= witching PA is to key the PA itself - ideally with a ramped waveform
<= div class=3D"gmail_default" style=3D"font-family:arial,helvetica,sans-serif= ;font-size:small">
WSPR uses phase continuous s= mall frequency transistions, so the Hi-Q antenna sees nothing to make it &#= 39;ring'

In the ea= rly days of 73kHz when people used=C2=A0 'Coherent', that was hard = switched 10 Bit-per-second=C2=A0 PSK some users reported damaged PAs.=C2=A0= My loading coil certainly made=C2=A0 clicking noises when the phase shifte= d, although the modified 100 Watts MOSFET audio amp=C2=A0 (a linear PA) sur= vived.



On Sat, 29 Sep 2018 at 11:09, Chris = Wilson <dead.fets@gmail.com&g= t; wrote:


Hello Andy,

Could=C2=A0 this=C2=A0 in any way supply a reason for me seeing the odd dea= d FET
when=C2=A0 running=C2=A0 OPERA=C2=A0 and=C2=A0 never=C2=A0 when=C2=A0 runni= ng WSPR? I always had the
feeling=C2=A0 that the fact OPERA stops and starts so many times in 32 mode=
that=C2=A0 it=C2=A0 was=C2=A0 a=C2=A0 cause=C2=A0 of=C2=A0 an occasional gl= itch that blew the FETS in my Class D
amp... To be honest it's the main reason I rarely TX with OPERA on LF.<= br> The=C2=A0 amp=C2=A0 is=C2=A0 permanently=C2=A0 powered,=C2=A0 the exciter, = normally my U3S then
stops=C2=A0 and=C2=A0 starts whatever mode is selected. With OPERA I think = a FET
will usually go at the START of one of the=C2=A0 TX cycles, not at the end.=

Thanks. 2E0ILY

Saturday, September 29, 2018, 9:42:10 AM, you wrote:

> If you stop and start a divider, the phase jumps about randomly.=C2=A0=
> Each time you start the divider, its output signal starts up in a
> differnet phase to what it would have been if left running


> To achieve phase coherent, you must keep the divider running and gate = the OUTPUT separately


> This issue is a problem with beacons in general that employ FSK
> keying for their CW ident.=C2=A0 =C2=A0If they adopted on-off keying, = then
> long term integration cold take place though the keying cycle.=C2=A0 B= ut
> unfortunately, IARU (or whatever organisation that tries to mandate > these things), appear to require FSK keying.=C2=A0 SO most beacon keep= ers
> comply.=C2=A0 =C2=A0(I don't, the Bell Hill microwave beacons, GB3= SCx all use on-off keying)
> Andy
> = www.g4jnt.com





--
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 =C2=A0 mailto:dead.fets@gmail.com


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