[Elecraft] Kio2 cablength

[Jack Brindle]

Jim;

I've learned quite a bit from you, and have a question about what you  
are saying here.

On Jul 7, 2005, at 8:48 AM, Jim Brown wrote:
>
> To gain the benefits of the twisting, use one pair (orange and
> orange/white, for example) to connect pin 2, with orange to pin 2 and
> orange/white to pin 5. Likewise, green to pin 3, green/white to pin  
> 5. The
> overall shield should go to the DB9 shell on each end, not to pin 5.
>
> If you are using UN-shielded twisted pair, connect the return of  
> each pair
> to the DB9 shell, NOT to pin 5. This puts a "band-aid" on pin 1  
> problems
> on each end.

We have gone out of our way in the RS-232 cables to avoid ground  
loops by not connecting the DE9 shell at one end (or in the case of  
the KIO2 cable, both). I have also seen this technique described  
(reference Bob Heil's web page), indicating that it is best to leave  
the computer end of the shield unconnected. So my question is why the  
suggestion to connect both ends here? Why doesn't this create the  
very ground loop problem we are trying to avoid?

Thanks. My engineering career has taught me that grounding, like RF,  
is magical - I continue to learn things about it that change my way  
of thinking.

- Jack Brindle, W6FB
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