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
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] 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
>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
><[email protected]> 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 <mailto:[email protected]>
> To: rsgb_lf_group
><mailto:[email protected]>
> 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
>
>
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