I needed a switch, one that would allow me to select the key or paddle that I wanted to use. So I begin looking for a switch to suit my needs among ham equipment suppliers, but found nothing. I finally found a couple of schematics on the web to build my own and decided to take that path.
I was about to start ordering the parts when a friend of mine was visiting the shack. I told him about building the switch and his response was; "why do you want to that, you can a switch on EBay that will be relatively cheap and do the job". He told me I wasn't Googling with the right words. He suggested I try "3.5mm audio switch ". Who knew? Much to my surprise and delight several devices came up that would meet my needs. Here is the link to the one I bought.
A cable with an 1/8" on one end (switchbox) and a 1/4" connector on the other, (K3 plug) works for the K3. Simply connect the switch via the cable to the radio and then plug in your keys, paddle, etc. into the switch. As can be seen below I have a straight key, bug and Winkeyer plugged into the switch, while the paddle is plugged directly into the radio. I actually have an empty port in the switch where I usually have a second bug plugged in. You could actually get a second switch that would allow multiple paddles to be at your disposal as well.
So when I'm chatting with my CW buddies I can change my method of sending code with the push of a button. I can answer a CQ'er with a like kind instrument. A guy calling CQ with a bug, I can answer with a bug, etc.. Very easy and very economical. There are 8 position switches available as well.