From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
References: <CAMFjj73hzB0vnSNhtR-cAm0Tp8RZoVbT02yiW4xnV9+h1OftNg@mail.gmail.com><DDBD5FEFA9D54CFBBA837A621F32FD94@gnat> <CAMFjj72M4-R9X1PJ8Apgd2xE5-GN3ADWRPHitTF1vJDibvAduA@mail.gmail.com>
In-Reply-To: <CAMFjj72M4-R9X1PJ8Apgd2xE5-GN3ADWRPHitTF1vJDibvAduA@mail.gmail.com>
Date: Mon, 8 Apr 2013 21:42:37 +0200
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Subject: RE: LF: Re: Hall Effect for Over-current shutdown?
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Hi Warren,

I know a German OM (RF engineer) who has recently implemented a hall =
sensor
for overcurrent shutdown for  his
home built 1KW short wave FET PA successfully.
I will ask him if he is willing to disclose his design and send it to =
you if
he agrees.

73
Clemens
DL4RAJ=20

=20

>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org=20
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Warren Ziegler
>Sent: Monday, April 08, 2013 9:07 PM
>To: rsgb_lf_group
>Subject: Re: LF: Re: Hall Effect for Over-current shutdown?
>
>Hi Alan,
>
>    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=20
>quickly in case too much current is being draw.
>I've modified the output transformer turns ratio to produce=20
>more power at lower supply voltages (I'm using 500V, 55a FETs).
>However with the new higher currents and with a new=20
>appropriate value sense resistor its developing a LOT of heat=20
>(12 W or so) and needs to be heat-sinked.
>I'm thinking Hall-effect might be more efficient and produce=20
>less heat - I'm pretty sure that others have used Hall effect=20
>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=20
><alan.melia@btinternet.com> wrote:
>
>
>=09
>	Ah interesting problem Warren.... why is it=20
>over-current?? if it is over-current because a high voltage=20
>has welded/melted a short between drain and source, then the=20
>protection wont help ....high currents usually lead to excess=20
>heating ......but what is the real cause? If you really need=20
>DC supply protection would not a high-side current monitor be=20
>easier/faster??? The problem then could be there is enough=20
>energy stored in the PA choke to zap the FET before, or even=20
>if, you can disconnect the supply.
>	=20
>	OK drive fails permanently on might be a condition it=20
>would protect the FETs against with DC coupled drive
>	=20
>	Alan G3NYK
>
>		----- Original Message -----=20
>		From: Warren Ziegler <mailto:wd2xgj@gmail.com> =20
>		To: rsgb_lf_group=20
><mailto:rsgb_lf_group@blacksheep.org> =20
>		Sent: Monday, April 08, 2013 7:15 PM
>		Subject: LF: Hall Effect for Over-current shutdown?
>
>		Anyone using a Hall effect device for=20
>overcurrent sensing and shutdown in a MOSFET amplifer?
>	=09
>
>		--=20
>		73 Warren K2ORS
>		                WD2XGJ=20
>		                WD2XSH/23
>		                WE2XEB/2
>		                WE2XGR/1
>	=09
>		 =20
>
>
>
>
>--=20
>73 Warren K2ORS
>                WD2XGJ=20
>                WD2XSH/23
>                WE2XEB/2
>                WE2XGR/1
>
> =20
>E-Mail ist virenfrei.
>Von AVG =FCberpr=FCft - www.avg.de
>Version: 2013.0.3272 / Virendatenbank: 3162/6232 -=20
>Ausgabedatum: 08.04.2013=20
>
>