Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dc01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 578CD380000B3; Mon, 8 Apr 2013 15:30:42 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPHPj-00014M-1D for rs_out_1@blacksheep.org; Mon, 08 Apr 2013 20:07:35 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPHPi-00014D-6m for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 20:07:34 +0100 Received: from mail-ob0-f181.google.com ([209.85.214.181]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1UPHPg-0000jH-4N for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 20:07:33 +0100 Received: by mail-ob0-f181.google.com with SMTP id wo10so1761597obc.12 for ; Mon, 08 Apr 2013 12:07:09 -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=Yl9yZA2+w6bQNYcgbI3duoWFNbWAwPdraOhvES285UI=; b=PcqUbQOP8yEZwkd3B/F0AEf+H+HRJz5vIivvLgWKqzj+GWim6y9/J21o+8noBdMmTY qx/W6FyrNxB8p7eD4PY0o+MggX94uzn837oy33dhNrEYMyOhRy4PXs7qymdnJ7phiigw gLTz8t+jWGEDMuUbFFpz6n/nbGXl303S65bOt3j5o91PJ8kHpu2eG3qM8bogY4dMXu7u kYnxoE1VnjjnZBBaG9Icw+On4hwz/auO5T1UFrDgmaI75aHsRPu2GQDtUIFPvdV8kZfX giAv4g/tRbTR/B+xOc/vrERAcGpyI6eqvMFxvwA6/MsfowlAZ/N1CNVhScqIu2vZ83h6 7zyw== MIME-Version: 1.0 X-Received: by 10.60.62.70 with SMTP id w6mr16988119oer.38.1365448029699; Mon, 08 Apr 2013 12:07:09 -0700 (PDT) Received: by 10.60.135.199 with HTTP; Mon, 8 Apr 2013 12:07:09 -0700 (PDT) In-Reply-To: References: Date: Mon, 8 Apr 2013 15:07:09 -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: 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. [...] 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 [209.85.214.181 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: 3efbf4053c1a70bbeb6c0a0cc657f05e Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary=089e01294f30c5215304d9de2467 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-dc01.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d408151631ae13c96 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --089e01294f30c5215304d9de2467 Content-Type: text/plain; charset=ISO-8859-1 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 --089e01294f30c5215304d9de2467 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Alan,

=A0 =A0 I've modifie= d the G0MRF amp with the M0BMU output configuration, I'm using a 30V su= pply.
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 va= lue sense resistor its developing a LOT of heat (12 W or so) and needs to b= e 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
<= div style>

<= br>
On Mon, Apr 8, 2013 at 2:52 PM, Alan Meli= a <alan.melia@btinternet.com> wrote:
Ah interesting problem Warren.... why is it=20 over-current?? if it is over-current because a high voltage has welded/melt= ed a=20 short between drain and source, then=A0the protection wont help ....high=20 currents usually lead to excess heating ......but what is the real cause? I= f you=20 really need DC supply protection would not a high-side current monitor be= =20 easier/faster??? The problem then could be there is enough energy stored in= the=20 PA choke to zap the FET before, or even if,=A0you can disconnect the=20 supply.
=A0
OK drive fails permanently on might be a conditio= n=20 it would protect the FETs against with DC coupled drive
=A0
Alan G3NYK
----- Original Message -----
From:=20 Warren Ziegler=20
Sent: Monday, April 08, 2013 7:15= =20 PM
Subject: LF: Hall Effect for Over-c= urrent=20 shutdown?

Anyone using a Hall effect device for overcurrent sensin= g and=20 shutdown in a MOSFET amplifer?

--
73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0=20 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0=20 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0=20 =A0 WE2XEB/2
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0=20 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
--089e01294f30c5215304d9de2467--