[Elecraft] K3 : PTT-KEY setting

[Keith Trinity WE6R]

That is the default behavior, you can change it, it is in the manual 
errata / addendum;
https://ftp.elecraft.com/K3S/Manuals%20Downloads/E740258E%20K3S%20Owner's%20man%20errata%20A1-2.pdf

PTT/KEY USE WITH THE USB PORT IMPROVED:   Some PC applications can 
control PTT and
KEY at the K3S via the RTS/DTR signals of the USB port. However, use of 
these signals may also allow
the PC’s USB port initialization to unexpectedly activate transmit at 
the K3S. This can happen if the
computer is turned on after the K3S, or if the USB cable is not 
connected. There is now a "Safe" mode
(the default) which disables PTT-KEY transmit until the K3S receives a 
command via USB, such as a
read of the rig's VFO frequency. To turn on safe mode on/off, go into 
CONFIG:PTT-KEY and tap '1' to
select "USB SAFE" or "UNSAFE". Exit the menu and turn the K3S off/on. 
Applications that use PTT
KEY via USB but never send commands may require "UNSAFE" mode. In this 
case, unwanted
transmit can be avoided by turning the PC on before the K3S.

More info from N6TV;
Inadvertent keying transmit unwanted TX Com Port keys radio PTT-KEY N6TV 
red LED.
Fix; Set your PTT KEY to OFF OFF, Or continue reading;
To prevent Windows reboots and USB cable connections from accidentally 
keying a K3S at boot time, I strongly recommend changing the Properties 
of all FTDI virtual serial ports, including those provided by the K3S or 
by the Elecraft KUSB cable or equivalent FTDI USB-to-Serial adapter.

The Windows default options are not good for FTDI devices, because the 
options "encourage" Windows to look for a serial mouse (!) or a dial-up 
modem (!) on the virtual serial port port at boot time, or whenever the 
USB cable is reconnected.  Those actions pulse the DTR and RTS pins 
about 7 times.

To prevent this unwanted behavior, always uncheck the box next to Serial 
Enumerator and always check the box next to Disable Modem Ctrl At 
Startup so it looks like this:

And MORE:
  More info re RTS DTR and PTT KEY, radio not keying via USB KIO3B, 
transmitting on digital modes, N6TV
PTT via RTS is supported by WSJT-X if you specify the correct serial 
port and enable the "PTT via RTS" option.  You cannot connect both USB 
cable and RJ-45 to DE-9F adapter cable to the K3S at the same time, and 
use both.  That doesn't work.  You cannot have two programs (like 
logging softare plus WSJT-X) connected to the same COM port at the same 
time.
There may be nothing wrong with the K3S, just a lack of understanding 
how to configure the PC software to key the radio for digital modes.  
The FT8 software (WSJT-X and JTDX), supports both PTT via RTS and also 
PTT via "CAT", which means it just sends "TX;" and "RX;" commands and 
CONFIG:PTT-KEY may be left set to OFF-OFF if using PTT via CAT 
commands.  But PTT via RTS should also work.
If you want to key PTT via RTS and CW via DTR you must set 
CONFIG:PTT-KEY to RTS-DTR.  You can verify that pulling the RTS Pin of 
the virtual serial port "High" keys the radio (and DTR keys CW), using 
my two free programs:
https://bit.ly/ToggleRTS
https://bit.ly/ToggleDTR
These links download a Zip file with a Windows executable.  Extract and 
read instructions in Readme.txt
IE make a shortcut to the .exe file and set the path for the comm port 
that comes up when you plug in the USB-B to the KIO3B, example; 
C:\Elecraft\ToggleRTS\ToggleRTS.exe COM28: 1000

Keith WE6R