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 x1QGoODf007515 for ; Tue, 26 Feb 2019 17:50:32 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gyfki-0002IR-IH for rs_out_1@blacksheep.org; Tue, 26 Feb 2019 16:38:44 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gyfkh-0002II-Jz for rsgb_lf_group@blacksheep.org; Tue, 26 Feb 2019 16:38:43 +0000 Received: from mail-ua1-x92c.google.com ([2607:f8b0:4864:20::92c]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1gyfke-0000tC-QL for rsgb_lf_group@blacksheep.org; Tue, 26 Feb 2019 16:38:42 +0000 Received: by mail-ua1-x92c.google.com with SMTP id d4so1321221uap.5 for ; Tue, 26 Feb 2019 08:38:40 -0800 (PST) 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=nB0DJVEqXxS4rgSRizNYWo2FGOE6GWlmNw1+PYEN9+I=; b=mdU8tco9CEhSDFuBHJmZZK9jntdvE12pM5dz+X0e7STWZbJe4XSosB0fPiaAG3W8xl fl68c4hqAiTiyly/xg6TTRKCa6X24AHaaZrRlvJZfPRVBBbqNck0c4ADqkQXu36RMEsE RvCYty/zawSi8cMNho388FXdaD40QtKEfcExQ/cKC4jJpMCy/ZbDd6fzJ+i5yWAmiRBC pChESN+aDYxPQKvogpmQQNcVSJpD8g9T6WsmTK35ho9lIk+4O30TyU/sDSlOtFKsxmPh jmsd+ChMSHUXPzRKgysGTE/tS/SmZP+dFVS80rq0MvQ7FStFoPsKMoKmrghmAJ2W5DXL vTcA== 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=nB0DJVEqXxS4rgSRizNYWo2FGOE6GWlmNw1+PYEN9+I=; b=Bagd8J1LOM/EFuaIKEH1QDxnziCoAnHDJmpE4671ii/XkBAMZuWn/FxhCGuSEWWcjQ D887pBSBcIEWXkhwZGPLaB4V06xH6CPqz9xr+x0JZt09F37rI2XwBy49BnXByFQSffpl dtg8TGP9PaC7/4/a0aqMEmqbqNZ6nYtu/BwVhAQ22uimHEBTA17fYf3a0lI+bDqCqZR3 RaKldqE9JFWUE2p9pNE3a7LHoScdzP2CaoDwT7Pj86NqKyHL44yF/So5TZM8suxjEHpQ m+CvDNi9cn5BkRibA0cuRQHGydGSROG7ig4o4m8bY13GHgDCZQLlg3+RkPAkPJ/BtVTd vDpw== X-Gm-Message-State: AHQUAuZ0QTlwbMR53edXLO+baxm3XKgbfOv4GFx29sBjcPDrA2UP0Lcp yX5nx/d9h6K7PJhxJzccZCcdXMnEuICuco90Yt5Syw== X-Google-Smtp-Source: AHgI3IZZ8uMC3yA27MRuwy8nYKdh89uK/+Fx9SY2AlJqUTSwqE6lRynLgBb4ftkdCoj13yJRHyN8aJf35hw6WAMJlkY= X-Received: by 2002:a67:ea84:: with SMTP id f4mr12067800vso.102.1551199117780; Tue, 26 Feb 2019 08:38:37 -0800 (PST) MIME-Version: 1.0 References: <942860C848184BA2A0A9103E0EE56DF7@DELL4> <1UTEEgOcyQ.DAejAuRZtn9@optiplex980-pc> <92784b07-a799-fb4e-9080-e1e8bb167b75@n1bug.com> <1UTEEhG1Ft.EdI1dlVbFOZ@optiplex980-pc> <3062ef19-bb69-3187-e8db-6a6bf5050739@n1bug.com> <234098919.20190226111836@gmail.com> <0a79de5c-3274-caae-c000-d5f49bb44540@no3m.net> <21240445.20190226160950@gmail.com> In-Reply-To: <21240445.20190226160950@gmail.com> From: Andy Talbot Date: Tue, 26 Feb 2019 16:38:15 +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 the administrator of that system for details. Content preview: AH - HA !!!!!!!!!!!! Therein may lie your problem. If you take your input direct to the 74F74 clock and don't hit that with anything other than a square wave you are bound to have problems. TTL device [...] 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:f8b0:4864:20:0:0:0:92c listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[at]gmail.com) 0.0 HTML_MESSAGE BODY: HTML included in message 1.0 FREEMAIL_REPLY From and body contain different freemails X-Scan-Signature: 4a8faa6952847c1ec651f883b63fc053 Subject: Re: LF: Class D current spikes Content-Type: multipart/alternative; boundary="000000000000642a150582ceb086" 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, TO_ADDRESS_EQ_REAL 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 --000000000000642a150582ceb086 Content-Type: text/plain; charset="UTF-8" AH - HA !!!!!!!!!!!! Therein may lie your problem. If you take your input direct to the 74F74 clock and don't hit that with anything other than a square wave you are bound to have problems. TTL devices (and F series really IS real TTL) get very unhappy with slow edges and can oscillate or show instability at the edges Even if you precede that with the classic inverter and linearising resistor, at low frequencies you will often see instability. That fed-back gate design usually works fine at tens of MHz and up, even MHz, but expect instability at kHz frequencies. Look at the output on a scope, and don't be surprised to see ringing on the edges , especially at low drive levels, and low drive levels are just what you get when the input waveform is keyed on / off At these frequencies, linear to logic conversion really MUST be done with a Schmitt trigger. 74xCT14 or similar. Use the ACT or HCT families as opposed to the HC or AC ones as they have a smaller hysteresis between Vin(HI) and Vin(lo), allowing for lower amplitude drive. They also need different centre biassing for AC coupled signals. Assuming a 5V rail, Use 2.5V for HC and AC families, 1.8V for ACT and HCT devices. Or an RS422 / RS485 line receiver works well; that has even lower hysteresis and hence lower permitted drive level. Andy www.g4jnt.com On Tue, 26 Feb 2019 at 16:14, Chris Wilson wrote: > > > Hello Eric, > > Yes, the output is a square wave when I use the U3S I take the output > direct from CLK0 at 2X frequency (set in the U3S menu) via a co-ax to > the input of the W1VD amp to Pin 3 of 74F74 with no 50 Ohm load > resistor. It works perfectly. It makes me think other exciters are > doing something different at the end of the TX cycle. I know not what > though... > > The amp is powered all the time, the output solely depends on the > presence or not of an input signal. > > Same with the TS-590S, output from the DRV socket at under 0dBm sine > wave at 2X frequency from the 590 into a squarer. Squarer drives the > W1VD amp the same, (no 50 ohm resistor) direct to Pin 3 of the 74F74. > no issues. Run the 590 at 136kHz into a W1VD doubler and a pre amp and > the FETS's life is always short. Death always seemingly occurs at the > end of a WSPR or OPERA cycle. Again the amp stays powered all the time > from either a huge linear supply or an HP SMPS 50V supply from a > server. > > I have noted that running the over current limiter on the linear on > the cusp of triggering helps. The SMPS is ruthless in the doubler > scenario and FET life is *always* on the edge. The gate waveforms seem > OK, it's the drain waveform that shows the spikes as the oscillations > decay away. I would love to get to the bottom of this as I have too > many different set ups to remember :) I assumed it was some sort of > feedback from the antenna perhaps, but I am a novice and once I found > what saved me from spending loads at Farnell I gave up chasing the > cause. > > Tuesday, February 26, 2019, 12:12:08 PM, you wrote: > > > Or in the case of a U3S with a square wave output at CLK0 (I assume it's > > square)... a complete positive half cycle without any further "noise", > etc. > > > On 2/26/19 7:04 AM, Eric NO3M wrote: > >> Just a thought, perhaps the RF is ending exactly at a zero crossing, > >> whereas a typical PC/soundcard + exciter may not be and that is > >> causing this issue. > > > > > > -- > Best regards, > Chris mailto:dead.fets@gmail.com > > > --000000000000642a150582ceb086 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
AH - HA !!!!!!!!!!!!
Therein may = lie your problem.=C2=A0 =C2=A0If you take your input direct to the 74F74 cl= ock and don't hit that with anything other than a square wave you are b= ound to have problems.=C2=A0 =C2=A0TTL devices (and F series really IS real= TTL) get very unhappy with slow edges and can oscillate or show instabilit= y at the edges

Even if you precede that= with the classic inverter and linearising resistor, at low frequencies you= will often see instability.=C2=A0 =C2=A0That fed-back gate design usually = works fine at tens of MHz and up, even MHz, but expect instability at kHz f= requencies.=C2=A0 =C2=A0Look at the output on a scope, and don't be sur= prised to see ringing on the edges , especially at low drive levels, and lo= w drive levels are just what you get when the input waveform is keyed on / = off

At these frequencies, linear to logi= c conversion really MUST be done with a Schmitt trigger.=C2=A0 =C2=A074xCT1= 4 or similar.=C2=A0 =C2=A0Use the ACT or HCT families as opposed to the HC = or AC ones as they have a smaller hysteresis between Vin(HI) and Vin(lo), a= llowing for lower amplitude drive.=C2=A0 They also need different centre bi= assing for AC coupled signals.=C2=A0 Assuming a 5V rail, Use 2.5V=C2=A0 for= HC and AC families,=C2=A0 1.8V for ACT and=C2=A0 HCT devices.

Or an RS422 / RS485=C2=A0 line receiver works well; = that has even lower hysteresis and hence lower permitted drive level.
=

<= /div>


On Tue, 26 Feb 2019 at 16:14, = Chris Wilson <dead.fets@gmail.com= > wrote:
=

Hello Eric,

Yes, the output is a square wave when I use the U3S I take the output
direct from CLK0 at 2X frequency (set in the U3S menu) via a co-ax to
the input of the W1VD amp to Pin 3 of 74F74 with no 50 Ohm load
resistor. It works perfectly. It makes me think other exciters are
doing something different at the end of the TX cycle. I know not what
though...

The amp is powered all the time, the output solely depends on the
presence or not of an input signal.

Same with the TS-590S, output from the DRV socket at under 0dBm sine
wave at 2X frequency from the 590 into a squarer. Squarer drives the
W1VD amp the same, (no 50 ohm resistor) direct to Pin 3 of the 74F74.
no issues. Run the 590 at 136kHz into a W1VD doubler and a pre amp and
the FETS's life is always short. Death always seemingly occurs at the end of a WSPR or OPERA cycle. Again the amp stays powered all the time
from either a huge linear supply or an HP SMPS 50V supply from a
server.

I have noted that running the over current limiter on the linear on
the cusp of triggering helps. The SMPS is ruthless in the doubler
scenario and FET life is *always* on the edge. The gate waveforms seem
OK, it's the drain waveform that shows the spikes as the oscillations decay away. I would love to get to the bottom of this as I have too
many different set ups to remember :) I assumed it was some sort of
feedback from the antenna perhaps, but I am a novice and once I found
what saved me from spending loads at Farnell I gave up chasing the
cause.

Tuesday, February 26, 2019, 12:12:08 PM, you wrote:

> Or in the case of a U3S with a square wave output at CLK0 (I assume it= 's
> square)... a complete positive half cycle without any further "no= ise", etc.

> On 2/26/19 7:04 AM, Eric NO3M wrote:
>> Just a thought, perhaps the RF is ending exactly at a zero crossin= g,
>> whereas a typical PC/soundcard + exciter may not be and that is >> causing this issue.





--
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


--000000000000642a150582ceb086--