Hi All
The historic way of keying a rig was through either a serial or parallel
port through a simple switched transistor or opto-coupler circuit to the
jack of the rig.
Now, the standard seems to be through the Winkey on a USB port.
It saves a load of faffing about with pressing rig memory buttons and risk
of inadvertent pressing of the wrong button on the front panel.
73
David W Wood