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 w38CLnUF016902 for ; Sun, 8 Apr 2018 14:21:50 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1f59Gq-00056a-EJ for rs_out_1@blacksheep.org; Sun, 08 Apr 2018 13:18:08 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1f59Gq-00056R-3H for rsgb_lf_group@blacksheep.org; Sun, 08 Apr 2018 13:18:08 +0100 Received: from resqmta-ch2-01v.sys.comcast.net ([69.252.207.33]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1f59Gm-0003ZD-Cc for rsgb_lf_group@blacksheep.org; Sun, 08 Apr 2018 13:18:06 +0100 Received: from resomta-ch2-15v.sys.comcast.net ([69.252.207.111]) by resqmta-ch2-01v.sys.comcast.net with ESMTP id 59EofrWMz6JVp59EofQRxk; Sun, 08 Apr 2018 12:16:02 +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=1523189762; bh=1vUf/1e0aH4zpG/lk7E/d/n0efL6Sp79HCp7putiG6Y=; h=Received:Received:From:Subject:To:Content-Type:MIME-Version:Date: Message-ID; b=d3SY6DXdrNUUdUdLt+3ceBDeSo9L+TDze7uPzfGxe4Njr577puZ3G0lbXeXEJSHrP eUoe/mrz4mG5ap0aH34R6UM0nlDcSirUFaVg1oqf5f9deXQYwnZNthj6DKJ8Q0ZrWz SSpOnd1OTu6PND9qieXRW4PNPOewHpoLaTOk+6tYvevh796NE5cCMkbUi7fJcgVdef hGja5SPec16TKTIUDBznZltD5xG/GE0xzSU7rwg/mz49ibYlmca+va0V+VLqIGVnVk Q/lIjdIB7a6gQGbajH/lnMBY4T/h18ReD0avXSXgH+WRjF2jBS/BxQBCp+uwaBySXP 4/+93imHtzhgQ== Received: from Optiplex980-PC ([73.4.253.141]) by resomta-ch2-15v.sys.comcast.net with SMTP id 59EkfYW0Gswa259Elf1bYp; Sun, 08 Apr 2018 12:16:01 +0000 From: "jrusgrove@comcast.net" To: "rsgb_lf_group@blacksheep.org" MIME-Version: 1.0 References: <162a4797468-1db9-bdf2@webjas-vae168.srv.aolmail.net> <1UQROqZht1.1c1VdzC0S69@optiplex980-pc> <52f42e30-7f6f-fc45-d3e7-782c1c845168@n1bug.com> Date: Sun, 8 Apr 2018 08:15:58 -0400 Message-ID: <1UQROrlNZc.2LoZ9LxbADe@optiplex980-pc> In-Reply-To: <52f42e30-7f6f-fc45-d3e7-782c1c845168@n1bug.com> User-Agent: OEClassic/2.7 (Win7; P; 2017-02-12) X-Mailer: OEClassic/2.7 (Win7; P; 2017-02-12) X-CMAE-Envelope: MS4wfEP96GljqebeTBk226mtX6yh9CoZJj++c+rnNNkvPxi7SVshIIGp9c8BwWB2HyoMmuy6hP+lEXH+MQhVNCltKTRCDjdHajCv/LrvSDVvxyoBeU71yadn 1bKh2525hUSjySM06mxI0XLU0aVguyCGquHBeUcqKOdXeD6XELhhUSYPya0FFXeIcpbMmfweyj0y/Q== X-Spam-Score: 0.7 (/) 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 Pressed for time so just a quick response. Notice the small 'bobble' (around 3 volts) on the gate waveform on the way up ... that's where the FET is turning on. Turn off is about the same level ... maybe a bit lower. As long as the gate waveforms don't overlap at that point it should be okay. A slight 'dead zone' (both FETs off) isn't a bad idea. [...] Content analysis details: (0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (jrusgrove[at]comcast.net) 0.0 HTML_MESSAGE BODY: HTML included in message 0.6 URIBL_SBL Contains an URL's NS IP listed in the Spamhaus SBL blocklist [URIs: www.n1bug.com] 0.1 URIBL_SBL_A Contains URL's A record listed in the Spamhaus SBL blocklist [URIs: www.n1bug.com] 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: e51657317b06d9cbe905ec682fad6602 Subject: Re: LF: W1VD amp help Content-Type: multipart/alternative; boundary="Z=_hemPITi2LLwv7x4NBBTZRvh2sLNoYp9" 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, 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 This is a multi-part message in MIME format --Z=_hemPITi2LLwv7x4NBBTZRvh2sLNoYp9 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Paul Pressed for time so just a quick response. Notice the small 'bobble' (around 3 volts) on the gate waveform on the= way up=20 =2E..=20 that's where the FET is turning on. Turn off is about the same level .= =2E. maybe a bit lower. As long as the gate waveforms don't=20 overlap at that point it should be okay. A slight 'dead zone' (both FE= Ts off)=20 isn't a bad idea. IIRC, the heating coil in an electric hot water heater (240 volt / 250= 0 watt?) is roughly 50 ohms. One can run a coax to it and use it as a = water cooled dummy load. At higher frequencies one might want to reson= ate out the inductance. Probably not much of an issue at 137 kHz. Jay W1VD ----- Original Message ----- From: N1BUG Reply-To: To: Sent: 4/8/2018 7:53:27 AM Subject: Re: LF: W1VD amp help Jay, Thanks for the detailed response! See below, threaded in. > HP3325A ... set frequency x2, square wave, amplitude 5 volts, dc > offset 2.5 volts. Have used the HP3325A here for countless numbers > of years. Done, verified that it looks OK with scope. (Previously I had not been testing with the DC offset!) =20 > Always start out on the dummy load. I've=20 reduced drain voltage to 13V so that I can do that. I have no dummy load which can handle the next step up (25V). No one near me does either. > Test in stages. Test the driver > into the FETs with the FET drain supply off. Verify the waveforms > with a dual trace scope to see that there's a small 'dead=20 zone' > between the two phases. There is a delay between one phase beginning to switch off and the other phase beginning to switch on, but I am not sure I would quite call it a 'dead=20 zone'. Sorry about the quality of images. Scope 5V/div. Gate waveforms: http://www.n1bug.com/gates1.jpg With the traces overlaid and time stretched out so you can better see the crossing between phases: http://www.n1bug.com/gates2.jpg It appears one has not fallen to zero by the time the other one is coming up. Should it? > Once the gate waveforms are confirmed to be correct, I've=20 paused testing at this point pending any comment on my gate waveforms or request to repeat with different settings. Paul --Z=_hemPITi2LLwv7x4NBBTZRvh2sLNoYp9 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Paul
 
Pressed for time so just a quick response.
 
Notice the small 'bobble' (around 3 volts) on the gate waveform o= n the way up ... that's where the FET is turning on. Turn off is about= the same level ... maybe a bit lower. As long as the gate waveforms d= on't overlap at that point it should be okay. A slight 'dead zone' (bo= th FETs off) isn't a bad idea.
 
IIRC, the heating coil in an electric hot water heater (240 = volt / 2500 watt?) is roughly 50 ohms. One can run a coax to it and us= e it as a water cooled dummy load. At higher frequencies one might wan= t to resonate out the inductance. Probably not much of an issue at 137= kHz.
 
Jay W1VD
 
 
 
 
----- Original Message -----
From: N1BUG <paul@n1b= ug.com>
Sent: 4/8/2018 7:53:27 AM
Subject: Re: LF: W1VD amp help
Jay,

Thanks for the detailed response! See below, threaded in.<= BR>
> HP3325A ... set frequency x2, square wave, amplitude 5 vol= ts, dc
> offset 2.5 volts. Have used the HP3325A here for c= ountless numbers
> of years.

Done, verified that it = looks OK with scope. (Previously I had not
been testing with the DC= offset!)
 
> Always start out on the dummy load.
I've reduced drain voltage to 13V so that I can do that. I have nodummy load which can handle the next step up (25V). No one near medoes either.

> Test in stages. Test the driver
>= into the FETs with the FET drain supply off. Verify the waveforms
= > with a dual trace scope to see that there's a small 'de= ad zone'
> between the two phases.

There is a delay betwe= en one phase beginning to switch off and the
other phase beginning = to switch on, but I am not sure I would quite
call it a 'dead zone'= =2E

Sorry about the quality of images. Scope 5V/div.

Gat= e waveforms:

http:/= /www.n1bug.com/gates1.jpg

With the traces overlaid and time= stretched out so you can better
see the crossing between phases:
http://www.n1bug.com= /gates2.jpg

It appears one has not fallen to zero by the ti= me the other one is
coming up. Should it?

> Once the gate= waveforms are confirmed to be correct,

I've paused t= esting at this point pending any comment on my gate
waveforms or re= quest to repeat with different settings.

Paul
<= /BODY> --Z=_hemPITi2LLwv7x4NBBTZRvh2sLNoYp9--