K3 Key Out - Let the Metal out of an IRFI630G MOSFET


Max NG7M
 

NG7M Max here... raising my hand with no shame! I pulled off frying the beefy Power MOSFET used on the K3 Key Out.  On the Schematic / PCB, it's Q3.  It's clear I ran 5+ amps through it.  This post might help someone else, because I didn't find any other posts in my short search where someone else was 'dumber than a bag of hammers' like me... maybe they were smarter and didn't fess up to it! :) (Jim W7CT, you can't post.  I'm not in the mood to take any crap from you! LOL!)


Here is a nice picture of what it looks like on an IRFI630 when you do this: (nice crack and molten metal ooz)


So my real question is... is there anything else to worry about?  I can't see anything else on the PCB around Q3 that appears to be funky.  I just ordered up 2 more 630's from mouser so I'll be able to fry another if so desired.  My K3 is working it appears, minus the keying.  It's not fun when you smell the smoke and it's coming from inside of your K3 case.  Needless to say, I dropped a few choice words.


For reference, which the next poor slob find helpful , here is the replacement on Mouser:


http://www.mouser.com/Search/ProductDetail.aspx?R=IRFI630GPBFvirtualkey61370000virtualkey844-IRFI630GPBF


So if you are still reading, what I was working on at my QTH where I run the NC7J DX Cluster and NC7J Skimmer Server was a keying interface so when I key my K3 it would cut the power to a couple of preamps I'm running on the antenna setup with the QS1R receiver.  I obviously have some issues with my hack design.


Please be gentle if you respond. ;)


Max NG7M



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