Good information, Pete. I had not really thought
about that. My impression was the LPT port had
ground on pins 18 through 25. I saw pins 11 and
25 in the manual and just hooked it up that way.
After the contest (of course) and "just for grins,"
I tried to run my interface box using CTWin 10.02.03,
NA 10.59 in a DOS window on Windoze 98SE, and CT-DOS
9.87, also in a DOS window. NA and CT-DOS keyed
fine, although I still need to determine from where
the hum is coming. CTWin didn't key it at all.
Backtracked to CTWin 9.92.01 -- it also didn't key
the interface at all.
LPT port set to ECP, if that matters.
73,
Bob
>The LPT "standard" function for pin 11 is a busy flag from the printer to
>the computer. When the printer asserts a logic one on this pin, the
normal
>LPT response is to stop sending data to the printer until the busy
flag is
>set low by the printer. It is a handshake pin indicating the status of a
>print buffer in the printer. So the electrical interface in most
computers
>is configured as a logic input. It cannot be used as ground. Pin 18 is
>the ground pin on the 25 pin LPT connector. The pin numbers above 18 are
>usually ground also, but some manufacturers may not have made all the
connections.
--
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: k3ph@ptd.net |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+
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