How to use a Straight Key and Paddles together on a KX3

When operating CW, sometimes it is nice to have both a straight key and a paddle connected to your radio simultaneously. You can use the paddle to easily make letters with machine accuracy, or you can switch to a straight key to add a personalized rhythm when desired.

There are various ways to accomplish this. One way is to use an external keyer, and just wire a straight key in parallel with the keyer’s output, and connect the parallel combination to the straight key input of your radio. But that requires an external keyer.

The Elecraft KX3 has two key connections, one on the left side of the rig that’s a that’s a standard 3.5mm stereo jack, and a nonstandard connector on the front that’s designed for the Elecraft KXPD3 paddle unit. Either jack may be configured via the menus to support a paddle or straight key.

If you have the Elecraft KXPD3 paddle unit, and want to use it as your paddle while using an external straight key, it’s very straightforward — just configure the 3.5mm jack as a straight key and plug your straight key into that jack while you also use the KXPD3 paddle.

But I have a non-Elecraft paddle, as well as a straight key. This is how I connected them both.

KX3 with Begali Expedition Paddle and Nye Viking Speed-X Straight Key

The paddle is connected to the key jack on the left side of the unit, in the conventional way. The straight key is just a little bit tricky, because it uses the KXPD3 paddle connection, but the connector is a bit unusual. The radio has a connector with four male pins, arranged in a square layout, with 0.1 inch spacing between them. However, only two pins are required for a straight key. It’s a lot easier to find two-pin connectors than four-pin square connectors of this type.

Connection of Straight Key to KX3

Here’s the secret: Just connect your straight key to the two rightmost pins of the KXPD3 connector. Then set the menu “CW KEY2” to “HAND”, and you’re all set. You’ve got a straight key connected, in a way that is completely independent of your paddle. The paddle will still use the internal keyer built into the KX3, and will still be able to record CW messages, and show your sent CW on the LCD display. But the straight key is ready to use whenever you want it, without pressing any buttons, switching any modes, or doing anything more complex than reaching over to tap on the straight key when you want to use the straight key, and moving your hand back over to the paddle when you want to use the paddle.

The KX3 SK Adapter which I made

I found a two-pin female connector with 0.1 inch spacing in my junk box. I soldered it to the tip and shield of a 3.5mm jack I also had in my junk box, to make my straight-key adapter.

My two-pin female connector had originally been used as an LED connector for a disk drive activity light in an ancient SCSI disk enclosure. You may find you’ve got a similar connector somewhere in your junk box, too. If you can’t find exactly the right connector, Digi-Key stocks part No 1175-1261-ND, which appears to have the correct connector on each end (caution — I haven’t bought one of these from Digi-Key, so I can’t guarantee a fit, but it sure looks right to me). Cut one of these in half and solder on the proper 3.5mm jacks, and you can make two straight key connectors. As an alternate, maybe you can use a pair of prototyping jumper wires with female ends, and connect each one separately.

73 de Rich/AG6QR