[Elecraft] MicroHam microkeyer

[Don Wilhelm]

Chris,

Yes, that is true - the SHELL on the DE9 connector is commonly listed as
protective (or frame) ground. Many interfaces do not implement or use the
Carrier Detect signal, but one never knows for certain unless you have
detailed info on the interface used.

That is also why the special computer to K2 cable does not attach pin 1 at
the computer end.  At the K2 end, pin 1 IS used as a ground to the K2
chassis, and it is important for ground loops prevention and reducing the
coupling of extraneous signals into the K2 that this shield be carried to
the computer end (but not terminated there).

The K2 9 pin connector, like many others, is NOT an RS232 serial port, and I
do not believe any claims otherwise have been made.  It is just a connector
that happens to have 2 RS232 signals (3 with signal ground) included in its
set of signals.  There is no standard for the connector itself, it is used
in a variety of applications.  So unless a connector is designated as a
serial port, make no assumptions that it really is - the K2 connector is
labeled on th erear panel as AUX I/O, and that is truly what it is - a
connector with auxiliary inputs and outputs, and must be interpreted in the
most generalized context of that labeling.

73,
Don W3FPR

> -----Original Message-----
>
> Hmm. Pin 1 on a DB25 for RS-232 is protective ground. On a DB9, it's
> Data Carrier Detect...
>
> This URL doesn't point to the EIA standard, but is the most
> practical explanation of serial connector wiring I've found:
>
> http://www.lammertbies.nl/comm/cable/RS-232.html
>
> 73 de chris K6DBG
>