Connecting a K3S, P3, and SteppIR Controller

Last August, I purchased a used three element SteppIR with a passive 6m element. It included a 2005 vintage Fluid Motion controller. Over the winter, I sent it to SteppIR to be checked out for recommended repairs and any upgrades that made sense. The controller is very old and will eventually need replacing (See Figure 1).

Figure 1 FluidMotion Controller

SteppIR assembled and tested the entire antenna at their facility to verify it worked. The found it in good condition overall and suggested several replacements and a couple upgrades that I went with. They told me to buy the cable for the K3S since I didn't have one when I bought the antenna. As part of my process, I reassembled most of the antenna in the basement and verified the controller moved the elements like they are supposed to. Everything checked out.

I then proceeded to connect the controller with the S26 cable to the K3S and just the controller. The antenna was still in the basement. The idea was to verify radio to controller function without damaging the antenna. Hurray, that worked as well! The controller moved the imaginary elements as the radio tuned across and changed bands. Not bad.

Now the problems began. I use a P3 and do rig control via USB from the K3S to my computer for logging software. I initially thought that I could simply connect the S26 cable to the computer side of the cable between the K3S and the P3. Not good. The P3 would work, but computer rig control did not! I tried rerouting the cables a couple different ways, but couldn't get the P3, FluidMotion Controller, and computer rig control to work. It seems that for the USB on the K3S to function properly when the P3 is connected the CBLP3Y cable from Elecraft must be connected to the PC connector of the P3. After exchanging a couple emails and phone calls to SteppIR, we theorized I needed the Y-cable as well. But we weren't sure if it would work. So I ordered it. SteppIR also supplied me with the hookup instructions that are not on their website. (I have had a great experience with customer service. Dan Walsh has always been very helpful.)

When the cable arrived, it was not immediately obvious how to hook this up. I figured that the portion labeled J1 in their diagram went to the controller. (J1 is the end connected to the thinnest cable in the SteppIR Y-cable.) But the question was how to hook up J5 and P2. (The two ends on the thickest part.) I decided to hook J5, which is the connector with two cables coming from it, to the computer plug of the Elecraft CBLP3Y cable (See Figure 2). The P2 connector from the SteppIR cable went to the PC connector on the back of the P3. Unfortunately, the screw connectors on the P3 and SteppIR Y-cable do not match. Both have nuts on them. I was able to remove the nuts from the P2 connector of the SteppIR Y-cable. I then plugged the P2 connector to the PC connector on the rear of the P3.

Figure 2 J5 connector attached to computer cable on P3.

At first, I was not able to get the controller to work this way. Then, I realized that I probably needed the SteppIR S26 cable so I connected it between the J1 connector of the Y-cable and the controller. Still no response. I then tried opening my rig controls software and it worked!!! I did some more testing and this still seems the only configuration that works. The controller will not start working until the rig control software is started. Once that happens, you can close it if you want. This behavior occurs no matter the software. I used DXLabs for my casual operating and DXing and N1MM+ for contesting.

Figure 3 Controller fully functioning.

Figure 3 shows the controller working beautifully. It's a great sight to see. I now need to bring the antenna up from the basement, connect it to the controller to verify full function before mounting it on the tower.

Figure 4 Cable wiring diagram.

I am sure the written description of the connections is slightly confusing. Figure 4 provides a better depiction of all the cables and connections. Hopefully, this helps you if you have a similar connection.