[Elecraft] K3 - KEY OUT problem

[M. George]

Bob N7WY motivated me to provide a few more details on the KEY OUT
mosfet/Q3/IRFI630 replacement.  I took the bottom off my K3 to show the
location of the IRFI630 on the bottom of the PCB.  It was a little more
tricky than I remembered, so you will need to access the main PCB from the
top of the K3 by removing the KIO3 board and the IO board that has the IF
output.  I did the replacement without removing the back panel which would
have been very painful.  Again, I do remember being able to do this without
a major disassembly.  I de-soldered from the bottom of the PCB and pulled
and replaced the IRFI630 from the top.  It was tight, but it sure beat
sending the K3 back to Elecraft and you can do a clean job if you are
careful.

Here are some new pictures that I just took
<http://www.nc7j.com/pa/main.php?cmd=album&var1=NG7M%2FRadios%2FK3%2FSmokedKeyOutIRFI630G%2F>
and annotated with more details of the location of Q3 along with a snippet
from the Elecraft Schematic where Q3 is located.  Your mileage may vary
based on your re-work skills but I wouldn't consider this a difficult
replacement... medium effort at worst.  When in doubt, send your radio in,
but it's not rocket science:

Updated Pictures:
http://www.nc7j.com/pa/main.php?cmd=album&var1=NG7M%2FRadios%2FK3%2FSmokedKeyOutIRFI630G%2F

Good Luck!

Max NG7M

On Sat, Dec 28, 2019 at 10:20 AM M. George <m.matthew.george at gmail.com>
wrote:

> Pete, just saw your question on the PTT OUT not working for you.  I had an
> issue with this back in 2016... I can't remember what I did, but it wasn't
> smart and it was my fault... Anyway, I let the smoke/metal out of the IRFI630G
> that is used on the PPT out.  It's beefy and can take a lot of abuse, but I
> still managed to destroy it.  Anyway, it's an easy replacement and saved me
> from shipping my K3 back to Elecraft.  Total operator error in my
> situation... maybe attached 12v to the PTT out?  Again, I can't remember.
>
> Here is a picture of what my damaged MOSFET looked like at the time... see
> the crack and leakage ;)
>
>
> http://www.nc7j.com/pa/main.php?cmd=imageview&var1=NG7M%2FRadios%2FK3%2FSmokedKeyOutIRFI630G%2FIRFI630GFried.JPG
>
> And here is the Mouser part I ordered to replace it:
>
>
> https://www.mouser.com/ProductDetail/Vishay-Siliconix/IRFI630GPBF?qs=%2Fha2pyFaduhSYcFgYMU8ma88%2Fb96%2Fl4SGKWFSYSWEuEDdoRAAyNpCg==
>
> Here is the schematic link:
> https://ftp.elecraft.com/K3/Manuals%20Downloads/K3_Schematics_Jun_2010.pdf
>
> Search for IRFI630 in the PDF, you will find it straight away... and I
> don't remember it being tough to expose the damaged mosfet and replace
> it...
>
> Max NG7M
>
> On Sat, Dec 28, 2019 at 8:57 AM N4ZR <n4zr at comcast.net> wrote:
>
>> Thanks to everyone who responded.  I've now written to Elecraft Support,
>> and anticipate that it will have to go back to the mother ship.
>>
>> --
>>
>> 73, Pete N4ZR
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>
>
> --
> M. George
>


-- 
M. George