Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mh03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 967B2380000B1; Mon, 8 Apr 2013 17:30:55 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPJCU-0001x8-DZ for rs_out_1@blacksheep.org; Mon, 08 Apr 2013 22:02:02 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPJCT-0001wz-Mm for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 22:02:01 +0100 Received: from nm4-vm0.bt.bullet.mail.ird.yahoo.com ([212.82.108.93]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1UPJCR-0001Ab-9x for rsgb_lf_group@blacksheep.org; Mon, 08 Apr 2013 22:02:00 +0100 Received: from [212.82.108.230] by nm4.bt.bullet.mail.ird.yahoo.com with NNFMP; 08 Apr 2013 21:01:36 -0000 Received: from [217.146.189.76] by tm3.bt.bullet.mail.ird.yahoo.com with NNFMP; 08 Apr 2013 21:01:36 -0000 Received: from [127.0.0.1] by smtp826.mail.ird.yahoo.com with NNFMP; 08 Apr 2013 21:01:36 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=s1024; t=1365454896; bh=KIe/aZD+qLupODKOPYCd733DCSANUJXN4CB6huni+BU=; h=X-Yahoo-Newman-Id:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:X-Rocket-Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-Antivirus:X-Antivirus-Status; b=Aj2o5viODbmt09ZEIRqLcEon/WQKVUkyY0QEP9nRmnMUwMR63XZf+MakNmY1A/vk9FwXfTi0YN9rGwnNjrAy9jUPTDmMiGCniBEeXzDKnfTqzwjRPuOw1pEu9GMt4nSTBIbLcaSaqWGaTeOfb/P/PhDLU54merPpiM+MpQzdsog= X-Yahoo-Newman-Id: 700258.61047.bm@smtp826.mail.ird.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: JGdeUKMVM1lRxNgSwdrokPAqWkTndhwLdCPev7S21U7ntfi s5z8AN28I92wemgjLUlziD2z1QiOOomWx08xQXsb1FjW3ADJ0OA.eJP1l3G2 BNec69WEw8ml8zbGelnrnusZyDYq0pcF0103EZjYK29x5HZ_BRmZiOwK484Q isMldl8VCMRvDxHfFvkDYRGMRFPOcGMkbNOpG8W07ULCGPSbOa7NM4_.Uh8j nKfH7v5f6d9mtlhLHD8IbCwgg9Z_1ob4F.sY.K6W6M_wD9wqmBGL_judRrmZ qiI4SBhPt1xpHtA2vm6Cml6yZQfh.CTWVA3qbug9Kr805DYPRWUzbYxIx4V_ OedBEHnkakFkcOpryj0gElkmAQZQXfLW7R6KI5YgZakJEhTSGf.aVXlzunvM zE2hmipIC.mTWO4neJ4TlePJ79Czt7hmWPm2ORiFVAvZB.0pd0hwKqVYP8C3 VUCvq4HjQfAsZ X-Yahoo-SMTP: fpz.2VeswBBs59bVshRPmMN51lcO2lgFRIvE4XTqE8dRwOxd70E- X-Rocket-Received: from gnat (alan.melia@86.149.140.116 with login) by smtp826.mail.ird.yahoo.com with SMTP; 08 Apr 2013 14:01:36 -0700 PDT Message-ID: From: "Alan Melia" To: References: <7EB77D10460A4EBF9E1F63437A4C99A6@gnat> <5163262C.60204@freenet.de> Date: Mon, 8 Apr 2013 22:01:34 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Antivirus: avast! (VPS 130408-1, 08/04/2013), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.0 (/) 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 Wolf I cant remember the ratings now but breaking 18A+ might be a bit cruel :-)) It would probably need more than a tap with a pencil to unstick it ! Alan G3NYK ----- Original Message ----- From: wolf_dl4yhf To: rsgb_lf_group@blacksheep.org Sent: Monday, April 08, 2013 9:18 PM Subject: Re: LF: Re: Hall Effect for Over-current shutdown? [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.82.108.93 listed in list.dnswl.org] 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: ae3221d431bd19e5880aa98eda07ece4 Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary="----=_NextPart_000_00F5_01CE34A4.A27BB420" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.5 required=5.0 tests=FORGED_MUA_OUTLOOK,HTML_30_40, 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-mh03.r1000.mx.aol.com ; domain : btinternet.com DKIM : pass x-aol-sid: 3039ac1d60d75163370f2303 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_00F5_01CE34A4.A27BB420 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Wolf I cant remember the ratings now but breaking 18A+ might be a bit = cruel :-)) It would probably need more than a tap with a pencil to = unstick it ! Alan G3NYK ----- Original Message -----=20 From: wolf_dl4yhf=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Monday, April 08, 2013 9:18 PM Subject: Re: LF: Re: Hall Effect for Over-current shutdown? .. 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 -----=20 From: Warren Ziegler=20 To: rsgb_lf_group=20 Sent: Monday, April 08, 2013 8:07 PM Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Hi Alan,=20 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 -----=20 From: Warren Ziegler=20 To: rsgb_lf_group=20 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? --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 =20 --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 =20 ------=_NextPart_000_00F5_01CE34A4.A27BB420 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Wolf I cant remember the ratings now = but=20 breaking 18A+ might be a bit cruel :-))  It would probably need = more than a=20 tap with a pencil to unstick it !
 
Alan
G3NYK
 
----- Original Message -----
From:=20 wolf_dl4yhf=20
Sent: Monday, April 08, 2013 = 9:18=20 PM
Subject: Re: LF: Re: Hall = Effect for=20 Over-current shutdown?

.. or wind a few turns of fat copper wire = around a=20 'reed relay' contact tube. Virtually no voltage loss then. I used this = for a=20 power supply, but it would work for the DC current feed inside a PA as = well.=20 IIRC, the product of number of turns * Amperes was about 50 for the = contact to=20 close.

73,
   Wolf .

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

Hi Alan,=20

    I've modified the G0MRF amp with the M0BMU = output=20 configuration, I'm using a 30V supply.
The G0MRF uses a current sense resistor to shut down the amp = quickly=20 in case too much current is being draw.
I've modified the output transformer turns ratio to produce = more=20 power at lower supply voltages (I'm using 500V, 55a FETs).
However with the new higher currents and with a new = appropriate value=20 sense resistor its developing a LOT of heat (12 W or so) and needs = to be=20 heat-sinked.
I'm thinking Hall-effect might be more efficient and produce = less=20 heat - I'm pretty sure that others have used Hall effect devices = to=20 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=20 over-current?? if it is over-current because a high voltage has=20 welded/melted a short between drain and source, then the = protection=20 wont help ....high currents usually lead to excess heating = ......but=20 what is the real cause? If you really need DC supply protection = would=20 not a high-side current monitor be easier/faster??? The problem = then=20 could be there is enough energy stored in the PA choke to zap = the FET=20 before, or even if, you can disconnect the = supply.
 
OK drive fails permanently on might be a = condition=20 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=20 PM
Subject: LF: Hall = Effect for=20 Over-current shutdown?

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

--
73 Warren K2ORS
      =  =20         WD2XGJ
      =  =20         WD2XSH/23
      =  =20         WE2XEB/2
      =  =20         WE2XGR/1

 =20 =


--
73 Warren K2ORS
      =  =20         WD2XGJ
        =  =20       WD2XSH/23
        =  =20       WE2XEB/2
        =    =20     WE2XGR/1

 =20
------=_NextPart_000_00F5_01CE34A4.A27BB420--