[WriteLog] Using the Sound Card

[Bill Turner]

On Tue, 19 Aug 2003 12:26:34 -0500, "Larry Alkoff"
<labradley at mindspring.com> wrote:

>I'd very much like the directions or at least the location of the header
>or wherever the output is available on the board.
>
>Thanks,
>Larry

_________________________________________________________

My pleasure.

Open up the KAM and look at the component side of the board with the
connectors toward you.  Near the upper left corner of the board you
will see two solder pads marked "SP" and "MA".  Those are the MARK and
SPACE outputs to drive the scope.  Now look near the DB-25 connector
and find another pair of pads, also marked "SP" and "MA".  All you
need to do is run a jumper wire from one "SP" to the other "SP", and
the same for the two "MA" pads.  The factory recommends you put a 100k
resistor in series with the wire to prevent possible damage to the KAM
in the unlikely event that voltage should accidentally be applied to
the outputs.  If you're sure that will never happen, omit the
resistors and just run a wire direct.

This gives you the MARK output on pin 11 of the DB-25 and the SPACE
output on pin 18.  Just run those, plus a ground wire, to the X and Y
inputs of the scope and that's all there is to it.  Shielded wire
should be used.  If I recall correctly, MARK is customarily applied to
the X input and SPACE to Y.  This doesn't really matter however.
You'll quickly get used to it either way.

You will see two crossed ellipses on the scope.  When the signal is
properly tuned in, the ellipses will be at 90 degrees to each other
and one will be vertical and one horizontal.  Mis-tuning will make
them tilted one way or the other.  Also, if the received signal has a
shift different from what the KAM is set for, they will be a little
more or less than 90 degrees from each other.  For ham radio, the
recommended shift is 170 Hz, and that's what your KAM should be set
for.  You will often receive signals with a 200 Hz shift, and the
ellipses will have more than 90 degrees between them - about 100-110
degrees.  In that case, just split the difference so each ellipse is
the same amount off its normal axis.  It's not that critical.

By the way, for those people like myself who use MMTTY or RITTY or
some other program for RTTY, you can still use the KAM as a scope
driver by itself without using it for actual demodulation.  My trusty
'ol KAM served well for many years as my demodulator but time has
passed it by for anything other than a tuning indicator.

Hope this helps.  Once you get used to the scope, you'll be spoiled
for any other tuning device, I guarantee.

-- 
73, Bill W7TI