[Elecraft] DSP/KPA100 combination

[charles]

On Thursday 01 February 2007 14:21, Lyle Johnson wrote:
> Hello Charles!
>
> > I would like to make contact with any builders who are currently putting
> > together the above combination, or any builders who have recently built
> > such a combination.
>
> I'm anticipating that your request has to do with fitting the DSPx
> module into the KDSP2, and then having the pins on the 20-pin conenctor
> interfere with the heatsink on the KPA100.
Yes you are correct Lyle.  I found that the corner of the pressed metal shield 
needed trimming and the pins on the surface mount unit to the DSP unit needed  
to be shortened.

> The present run of DSPx module have pins that are slightly too long, and
> the 20-pin receptacle on the KDSP2 board has stops that prevent the pins
> from "over engaging".  The net result is that the KDSP2 doesn't seat
> completely on the KDSP2, and the tops of the pins are in contact with
> the KPA100 heatsink.
> The solution is to trim the pins on the DSPx module.  If you trim off
> about 0.090" from the 20-pin male connector pins, it will mate and seat
> as intended.  The dimension isn't a precise requirement; if you mark the
> pins between 0.100" and  0.125" back from the tip and then trim you
> should be fine..
I actually reduced the length of the pins by 3/32", about .094".
I did this by cutting the ends off with a small pair of wire cutters, then 
filing them all to the same length with a diamond lap, then removing the 
burrs and filing a slightly splayed end so that they easily pushed in right 
home. The right grade of diamond lap will only remove a little at a time so 
that the amount being removed can be controlled and a smooth finish is 
achieved.

This problem caused me a great deal of bother because the PA worked perfectly 
first time when it was sitting beside the K2 but when it was mated with the 
K2 it was impossible to see what the problem was.  All I knew was that I had 
completely lost audio.  I then realised that this was because the surface 
mount unit on the DSP was being grounded by the metal shield due to a clash.

As well as shortening the pins I also had to do quite a bit of filing to the 
shield to get it to fit properly. The PA is now easily fitted to and removed 
from the K2.

Anyway, after quite a struggle and lost time I now have a very happy K2/100 
which this morning enabled me to work HZ1AN in Jeddah :-)

> I suggest you *not* use "flush cutting" pliers as these leave the pin
> ends very blunt.  Normal diagonal cutting pliers will do the job just
> fine.  You do *not* need to grind or file or sand them to have pyramid
> tips.
> Finally, you might want to use a felt-tip pen to mark the pins to be
> cut. This helps to trim them to about the same length, although this is
> not critical.
> Sorry for the error on the DSPx pin lengths...

All's well that ends well !!
I just wanted to make other builders aware of this problem and the way in 
which it can easily be solved - when you know how.
Gary Surrency has told me that Elecraft intend issuing a "Builder's Alert" 
about this issue but I haven't seen it appear yet.

Thank you for your reply Lyle.
It's an absolutely super radio and with the KAT100-1 sitting underneath it's a 
very useful tool for a CW op. My thanks to Eric for the design and to Wayne 
and the rest of the Elecraft team for providing me with hours of satisfaying 
fun in building the kit and for many, many more hours of operating yet to 
come.

73 from Charles - M0BIN