[Elecraft] [KX3] RS232 xcvr control when serial ports are occupied

[dick at elecraft.com]

Typically "sniffers" don't have the TX side connected.  RS-232 can't have
multiple transmitters on either wire.

This is done with SteppIR controller, for similar reasons.  SteppIR
describes a splitter cable for DE-9 connectors. The same principle (with a
much simpler cable, just tip and ring) applies to the 3.5mm connector to the
KXPA100.

 http://www.steppir.com/wp-content/uploads/2011/10/Y-Cable.pdf

73 de Dick, K6KR


-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On
Behalf Of Stephen Rector via Elecraft
Sent: Sunday, July 8, 2018 12:31
To: elecraft at mailman.qth.net
Subject: [Elecraft] [KX3] RS232 xcvr control when serial ports are occupied

Hy home station is a KX3 + KPXA100, and I can control the radio via the
RS232 port on the KXPA. However, recently I added a Ciro Mazzoni magloop to
the station, and its controller plugs in to the KXPA serial port to sniff
for frequency information, allowing re-tuning on the fly. This leaves no
RS232 port left for remote control of the radio.

How do I modify this arrangement to add an extra serial port for KX3
control? My first thought is that, since the antenna controller just sniffs
for data, I could add a DB-9 Y-cable to provide the extra port at the
controller serial port location. However, packets could still collide
...does the protocol handle this? Is there some sort of multiplexer
available?

Thanks,

Steve

NU7B
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