Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mp01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 378A1380000BB; Tue, 9 Apr 2013 11:36:08 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPa4J-00011H-K8 for rs_out_1@blacksheep.org; Tue, 09 Apr 2013 16:02:43 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPa4J-000111-06 for rsgb_lf_group@blacksheep.org; Tue, 09 Apr 2013 16:02:43 +0100 Received: from mail-oa0-f47.google.com ([209.85.219.47]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1UPa4G-0003wI-Lr for rsgb_lf_group@blacksheep.org; Tue, 09 Apr 2013 16:02:41 +0100 Received: by mail-oa0-f47.google.com with SMTP id o17so7436031oag.20 for ; Tue, 09 Apr 2013 08:02:19 -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=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=QxujLCVgvlHxD/bT1QxCY+fGLB/qfw0kHZIeX3MGb8Q=; b=X/YkkW3X0zV6kWRwH4shTj5ivl9+z+C2nJ+Ho7YE35E/bn+hGGrKIJI+oXIU+horzf 7j16/NhCV8/iim2IupsN7WDN9zDXr5P9jQSt+3fWap0gnmLSQylj4djAajCxPYpA9ScR 9DJ+buPjRk+UDe5bfQqmdcQEVvCIrJ5f3+pu2R0Gg2b3bbgL94dFgxtp9ePglNqYg57M CO6shrYPuYUICF3eGXpP1xplg3PMFT8u3NfoaRB+m1KOTudYnvnKvmnG9Dm2wli7Y+Jb GWYTMIbfkkKAuJNx0eVpv9Bn8GyP9U4WHjDU4nuWZ/Lf79boPhJLmxZnnon1asf7K1Tv 8gxw== MIME-Version: 1.0 X-Received: by 10.60.116.73 with SMTP id ju9mr18427918oeb.75.1365519738990; Tue, 09 Apr 2013 08:02:18 -0700 (PDT) Received: by 10.60.135.199 with HTTP; Tue, 9 Apr 2013 08:02:18 -0700 (PDT) In-Reply-To: <5163262C.60204@freenet.de> References: <7EB77D10460A4EBF9E1F63437A4C99A6@gnat> <5163262C.60204@freenet.de> Date: Tue, 9 Apr 2013 11:02:18 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Wolf, interesting idea, but doesn't contact closure take about 10ms? 73 Warren On Mon, Apr 8, 2013 at 4:18 PM, wolf_dl4yhf wrote: [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.219.47 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (wd2xgj[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 X-Scan-Signature: 396a95bbad9af60b2ee566edcd35b39e Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary=089e0115f322f9f6bd04d9eed6e7 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNSAFE,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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-mp01.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1dc145516435660e62 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : temperror --089e0115f322f9f6bd04d9eed6e7 Content-Type: text/plain; charset=ISO-8859-1 Wolf, interesting idea, but doesn't contact closure take about 10ms? 73 Warren On Mon, Apr 8, 2013 at 4:18 PM, wolf_dl4yhf wrote: > .. or wind a few turns of fat copper wire around a 'reed relay' contact > tube. Virtually no voltage loss then. I used this for a power supply, but > it would work for the DC current feed inside a PA as well. IIRC, the > product of number of turns * Amperes was about 50 for the contact to close. > > 73, > Wolf . > > Am 08.04.2013 21:39, schrieb Alan Melia: > > Ah yes that is Class D and can go that way if mis-matched......that is a > lot of power in a sensing resistor! I guess a Hall effect device or even a > temp sensor would do that job. I think in over current condition a lot of > power is dissipated in the devices. High side sensors should be available > at 30v The sheets I have seen, suggest they require some assistance above > about 40v. > > Alan > > ----- Original Message ----- > *From:* Warren Ziegler > *To:* rsgb_lf_group > *Sent:* Monday, April 08, 2013 8:07 PM > *Subject:* Re: LF: Re: Hall Effect for Over-current shutdown? > > Hi Alan, > > I've modified the G0MRF amp with the M0BMU output configuration, I'm > using a 30V supply. > The G0MRF uses a current sense resistor to shut down the amp quickly in > case too much current is being draw. > I've modified the output transformer turns ratio to produce more power at > lower supply voltages (I'm using 500V, 55a FETs). > However with the new higher currents and with a new appropriate value > sense resistor its developing a LOT of heat (12 W or so) and needs to be > heat-sinked. > I'm thinking Hall-effect might be more efficient and produce less heat - > I'm pretty sure that others have used Hall effect devices to protect MOSFET > amplifier and I'm looking for circuit tips. > > 73 & Tnx! > Warren > > > > > On Mon, Apr 8, 2013 at 2:52 PM, Alan Melia wrote: > >> Ah interesting problem Warren.... why is it over-current?? if it is >> over-current because a high voltage has welded/melted a short between drain >> and source, then the protection wont help ....high currents usually lead to >> excess heating ......but what is the real cause? If you really need DC >> supply protection would not a high-side current monitor be easier/faster??? >> The problem then could be there is enough energy stored in the PA choke to >> zap the FET before, or even if, you can disconnect the supply. >> >> OK drive fails permanently on might be a condition it would protect the >> FETs against with DC coupled drive >> >> Alan G3NYK >> >> ----- Original Message ----- >> *From:* Warren Ziegler >> *To:* rsgb_lf_group >> *Sent:* Monday, April 08, 2013 7:15 PM >> *Subject:* LF: Hall Effect for Over-current shutdown? >> >> Anyone using a Hall effect device for overcurrent sensing and shutdown >> in a MOSFET amplifer? >> >> -- >> 73 Warren K2ORS >> WD2XGJ >> WD2XSH/23 >> WE2XEB/2 >> WE2XGR/1 >> >> >> >> > > > -- > 73 Warren K2ORS > WD2XGJ > WD2XSH/23 > WE2XEB/2 > WE2XGR/1 > > > > > -- 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 --089e0115f322f9f6bd04d9eed6e7 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Wolf, interesting idea, but doesn't contact closure ta= ke about 10ms?

73 Warren



On Mon= , Apr 8, 2013 at 4:18 PM, wolf_dl4yhf <dl4yhf@freenet.de> wr= ote:
=20 =20 =20
.. or wind a few turns of fat copper wire around a 'reed relay' contact tube. Virtually no voltage= loss then. I used this for a power supply, but it would work for the DC current feed inside a PA as well. IIRC, the product of number of turns * Amperes was about 50 for the contact to close.

73,
=A0=A0 Wolf .

Am 08.04.2013 21:39, schrieb Alan Melia:
=20 =20 =20
Ah yes that is Class D and can go that way if mis-matched......that is a lot of power in a sensing resistor! I guess a Hall effect device or even a temp sensor would do that job. I think in over current condition a lot of power is dissipated in the devices. High side sensors should be available at 30v The sheets I have seen, suggest=A0they require some assistance above about 40v.
=A0
Alan
----- Original Message -----
Sent: Monday, April 08, 2013 8:07 PM
Subject: Re: LF: Re: Hall Effect for Over-current shutdown?

Hi Alan,

=A0 =A0 I've modified the G0MRF amp with the M0BMU outpu= t configuration, I'm using a 30V supply.
The G0MRF uses a current sense resistor to shut down the amp quickly in case too much current is being draw.
I've modified the output transformer turns ratio to produce more power at lower supply voltages (I'm using 500V= , 55a FETs).
However with the new higher currents and with a new appropriate value sense resistor its developing a LOT of heat (12 W or so) and needs to be heat-sinked.
I'm thinking Hall-effect might be more efficient and produce less heat - I'm pretty sure that others have used Hall effect devices to protect MOSFET amplifier and I'm looking for circuit tips.

73 & Tnx!
Warren




On Mon, Apr 8, 2013 at 2:52 PM, Alan Melia <alan.melia@btinternet.com> wrote:
Ah interesting problem Warren.... why is it over-current?? if it is over-current because a high voltage has welded/melted a short between drain and source, then=A0the protection wont help ....high currents usually lead to excess heating ......but what is the real cause? If you really need DC supply protection would not a high-side current monitor be easier/faster??? The problem then could be there is enough energy stored in the PA choke to zap the FET before, or even if,=A0you can disconnect the supply.
=A0
OK drive fails permanently on might be a condition it would protect the FETs against with DC coupled drive
=A0
Alan G3NYK
----- Original Message -----
Sent: Monday, April 08, 2013 7:15 PM
Subject: LF: Hall Effect for Over-current shutdown?

Anyone using a Hall effect device for overcurrent sensing and shutdown in a MOSFET amplifer?

--
73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0



--
73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0




--
73 Warren K2= ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0
--089e0115f322f9f6bd04d9eed6e7--