More on N0SS K3 External Speaker Splitter

[Ken Kopp-3]

As one of the first of -many- who have managed to "blow up" the audio
output IC in my K3, I'm qualified to comment. (;-)

First, I'm fortunate in that I caught my failure quickly and only scorched
the board.  I know of others who's boards were burned black / charred.  My
"event' happened early-on in the time frame of this issue.  I called Scott,
had a conversation about the failure and was promptly sent a replacement.

It was my -impression- at that time the cause of the IC failures wasn't
really obvious, and that the IC was running at close to it's max capability.  
(Elecraft isn't known for doing this.)  Therefore, I fabricated a multiple-finned
copper sheet heat sink for the IC and placed it under the IC when I soldered
it to the board.  I understand there is now more "land" along the top of the
board for additional heat-sinking of the IC.    

When I turned the radio on after the replacement, I stuck my finger down
through the opening to feel the (added) heat sink and immediately checked
my reaction time!  It was HOT!  The overheating problem was still with me!

It was only then that I did what I should have done first ... determined the
actual cause of the IC's failure.  Like many, I had used a short 1/8" stereo
"Y" cable to feed two external speakers.  These speakers both had mono
plugs, thereby shorting the right channel and causing the IC to overheat.

Since my "event" I've always felt the manual is remiss in -strongly- alerting
the user of the potential problem of plugging in a mono-plugged speaker.  
Yes, if one reads carefully and understands what's being said, the caution
is there, but not all fully absorb the text's caution. Who reads the manual
about the simple act of plugging in an external speaker? (:-)

Elecraft has now added software and hardware "features' to protect us
from ourselves, and now Tom is doing the same.

As I said at the beginning ... I'm qualified to comment.  READ THE BOOK!
Even for the seemingly simple tasks.

73! Ken Kopp - K0PP
     [hidden email]


Tom and the List....

I appreciate Tom's design and a neat PCB package, but come on folks.  This is easy to breadboard and stick in a plastic box.  Go to Radio Shack....buy a little black project box...buy some connectors.  You can use 3.5 mm jacks or RCA jacks.  You can find them there to "hole" mount.  Take some time and drill a couple of holes and then hardwired the box.  Easy Peasey.  No need for a PCB and all that stuff.  How about some hook up wire in your junk box?  Look around and you can find away to make this easy device without all the hassle.

Nice job Tom....you make it nice when you make the PCB...but there is no shame of just using hook up wire in a box.  

Lee - K0WA

In our day and age it seems that Common Sense is in short supply.  If you don't have any Common Sense - get some Common Sense and use it.  If you can't find any Common Sense, ask for help from somebody who has some Common Sense.  Is Common Sense divine?

Common Sense is the image of the Creator expressing revealed truth in my mind. -  J. Wolf






________________________________
From: Tom Hammond <[hidden email]>
To: [hidden email]
Sent: Mon, January 4, 2010 1:20:07 PM
Subject: [Elecraft] More on N0SS K3 External Speaker Splitter

Since the posting of the link to my K3 Speaker Splitter PC board, I
have received a number of requests (orders if you will) for PC boards.

I've been thinking about the problems some may encounter with regard
to ordering the specific parts (PCB-mount 3.5mm stereo jacks) for the
splitter, and more importantly the off the wall cost of shipping
(usually $5-$7 US) for less than 3 oz of parts (and that's per each
order placed).  This raises the cost of the project significantly.

I already have enough orders for PC boards that I'll not be able to
fabricate them in the Kitchen (as I often do for very small PCB
orders), and IF I proceed with the project from this end, I'll have
FAR Circuits make the PC boards for the project. This will increase
the cost of the project (just a bit), BUT it'll take a load off me,
AND it'll help keep me in Jeri's (She Who Must By Obeyed) good graces...!!!

I am proposing to completely 'kit' the project... all electronic
parts, hardware, and PC boards... for $20 or less, delivered to US
destinations... add $1 more for DX delivery.

My initial PCB order will be for one 'sheet' of thirty (30) boards
(main circuit board and an 'insulator' board to prevent the main
board from shorting out against anything on the operating desk in
back of the K3.  To that end, I'll need a few more orders before I'll
be able to commit to the cash outlay for the PC boards.

IF you are interested in obtaining a kit for this project, PLEASE
contact me a.s.a.p. I will make my final decision (GO or NO-GO) by
the end of this week.

If you are interested, you can see the docs on a previous version of
the Splitter at:

    http://www.n0ss.net/index_k3.html

and drop down to the line titled: "External (Dual) Speaker Splitter
for the K3".

The proposed project will be slightly smaller than that shown on my
web page and will use 2-56 hardware as opposed to 4-40 hardware in the article.

73,

Tom Hammond   N0SS
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