[Elecraft] K3S RS232 "Y" Connector causing port conflict

[charles at k5ua.com]

Thanks for the detailed explanation Don. It seems like that is what is
happening, the OM2500 may be sending info back on the line into the "Y"
connector, confusing Na3P on the computer end on making the OM2500 jump
frequency rapidly back and forth between the correct frequency and the
out-of-band phantom frequency. From the responses, there may be 3
possible solutions:

(1) I read N8LP's comment under a different thread heading than this
one. I am using his LP-Bridge program and LP-Pan hardware. Larry said
that I could use one of the extra serial ports in LP-Bridge to send data
to the OM2500A. I think that will work if I put a Serial to USB
converter coming out of the RS232 port on the OM2500A going back to a
USB port on the computer.

(2) If all else fails, I have used DDUTILl in the past to talk to the
OM2500A using the CI-V format into the CI-V port of the OM2500A. I don't
really want to use two virtual serial port programs (DDUTIL and
LP-Bridge), but I might have to try that.

(3) I will email OM Power to ask if I can put the OM2500A into "passive
listener" mode only. I thought that I might be able to accomplish the
same thing by removing the wire in the DB-9 cable that would carry
signals from the OM2500A back to the "Y connector, thereby making it a
"passive listener" by default. If you look at the K3S DB-9 wire
definitions in the manual, one of the wires is RX and one is TX. I was
thinking that if I removed the Line 3 TXD OUT pin from the cable going
to the OM2500A, any signals coming from the OM2500A would never get back
to the "Y" connector to confuse the computer that is listening on the
same line.

On page 18 of the manual there is a table of the DB-9 pin-out. Although
the names of the pins seem counter-intuitive to me.....
Pin 2 (RXD IN) is used to _SEND_ data from the K3 _TO_ the PC and the
OM2500A.
Pin 3 (TXD OUT) is used to _RECEIVE_ data _FROM_ the PC or the OM2500A.

I'm thinking that removal of Pin 3 from the side of the "Y" splitter
that goes to the OM2500A will allow the OM2500A to _RECEIVE_ signals
from the K3S/PC _BUT NOT SEND_ signals to the K3S/PC. Does that make
sense? Would like to receive comments on these three possibilities.

Thanks for all who responded.

Charles K5UA