[Elecraft] K2 - Fuses ...A Cautionary Tale

[Ron D'Eau Claire]

Ah, but you know us Humans are lousy at two things:

1) Thinking when we're distracted or under stress. 

2) Paying attention to detail. 

IIRC, Eric reversed those cables on an early KPA100 at a Hamfest while
talking with people and smoked the amp. That's when the blocking capacitor
in the RF input was added. 

That's why we have speed limits that are always too low and stop signs where
they don't seem to be needed - for the times we are distracted or not paying
attention.

And in aircraft,  ships and other critical places, we have check lists,
check lists and check lists. 

Ron AC7AC

-----Original Message-----
OK -- There are *dumb* things, and there are *stupid* things - and 
sometimes it is difficult to separate the two.  So go write yourself a 
"dear dummy" letter and let it go at that.

Yes, the two connectors for AUX RF and AUX 12V are the same, and if 
exchanged, you will have a DC short to ground - better to sacrifice a 
bit of PC trace than to encounter significant component damage.  I don't 
see that exchanging the two connectors is a major hazard - the KPA100 
(or KBT2) connector if built to the specified length is not long enough 
to interchange the connectors easily - yes, it is possible, but not easy.

Check that the length of your AUX 12V leads are the correct length (4.5 
inches) and that the input coax to the KPA100 is the correct length 
(also 4.5 inches) and it should be difficult to connect both cables to 
the K2 RF board with the cables reversed - while it is possible, it is 
not as easy as connecting them correctly.

So, the bottom line is (IMHO) - fuse all DC sources at the rating for 
the load, and follow instructions.  For those times when you do not do 
things correctly and S**T happens, just say "AH S**T" and go on with 
life as it may be.

I used to work for IBM, and there was a desk plaque that had the word 
"THINK" on it.  Well, that is what I am asking you to do - "THINK" - it 
will make a lot of difference.  BTW, the publication "Think" is now the 
property of Case Institute of Technology (My Alma-mater), and is the 
official alumni magazine.

73,
Don W3FPR