Steve,
If the cable to the computer is built as specified in the KIO2 (or KPA100)
instruction manual, noise pickup is minimized - the frame ground (pin 1) is
connected only at the K2 end, and any noise on the computer frame ground is
not conducted onto the cable. I would expect any improvement gained by
using optoisolators to be minimal - perhaps someone should try it and see.
Optoisolators are useful as a solution for ground loops in situations where
they are likely to occur - such as instances when the connecting cable
parameters are not known or specified. One advantage to optoisolators is
that separation of the signal ground in addition to frame ground is
possible, but proper care must be exercised in the design to assure that
this isolation is still present after the circuit is packaged (frame ground
can be inadvertently made continuous even with the use of optoisolators by
conduction through a metallic enclosure).
There is little advantage to be gained by separating the signal ground for
RS-232 level signals unless the cable run is very long (more than 50 feet or
so) and ground reference level shift creates a problem with the switching
levels at the receiver.
For my $0.02 worth, I would not predict any improvement.
73,
Don W3FPR
----- Original Message -----
Hi all,
I noticed that the KIO2 option uses a standard conversion chip like the
Maxim 232, but does not use optoisolators. I guess the optoislators would
not help when the KIO2 is inside the radio close to the other circuits. I
also noted that the KIO2 can generate noise. Has anyone ever considered
using the KIO2 with optoisolators added outside of the K2 chassis? My
limited experience with my homebrew interface for a Kenwood CAT says that
it
would be much easier to eliminate the interference, and since the cable to
the computer is outside the radio, the RS232 interface being outside the
radio would not be much of an inconvienience. Just a thought.
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