Re: Went Dead

Arv Evans

Just replacing the IRF-510 devices may not be enough.  Something caused the failure.  Was it
an intermittent antenna connection that drove SWR too high?  Or was it a power spike that
punched through the MOSFET structure?
Finding and fixing the cause might be the first order of business, before replacing the damaged

Arv  K7HKL

On Fri, Jun 15, 2018 at 1:43 PM Clark Martin <kk6isp@...> wrote:
With the symptoms described there is a microscopic chance it’s something other than a shorted MOSFET.  You might want to consider replacing both final transistors.  Whatever killed the one that is shorted may have damaged the other.  Make sure to buy several spares, this may not be the first time you need to replace them.

I’d strongly suggest putting a fuse inline, this may protect the final transistors from future damage and also protect your power source from overload if it does happen again.

Make sure you replace the thermal grease between the transistors and heatsink.  Don’t forget to set the bias adjustment for the new transistor (you should probably verify the bias adjustment for the other.

Below are some reputable sources for replacement IRF510s:

Clark Martin

> On Jun 15, 2018, at 12:24 PM, Bill Watkins <kf7yxs@...> wrote:
> Thanks,
> So, one mosfet is shorted.  I'm no electronics wiz so I have to ask basic questions.  It's an irf510, right?  Fry's electronics shows no item of that name.  Is there another company that makes something generically the same, or is there a similar item available at Fry's that I can replace it with?
> Is that the real issue?  With the zero ohms from source to drain on one transistor and with the unit powering up when brown wire disconnected is shorted mosfet the answer to this problem (at least short-term, anyway)?

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