Homebrew Cootie/Side Swiper

Playing radio with the Straight Key Century Club (SKCC) is fun, and I wanted to try out a new key so I went to Lowe’s and spent about $20 on some stuff to make a Cootie or Side Swiper.

Parts needed:

4 – small brackets with screws
3 – #10-32 x 3/4″ screws
8 – #10-32 nuts
1 – hacksaw blade
2 – furniture slider felts
– wood or some kind of base
1 – zip tie
– a few feet of wire (2 or 3 conductor)
1 – mono or stereo plug that fits your rig

The first step was to sand the paint off of the saw blade. I used a wire wheel to make this easy. Then I cut a 4.5″ piece of the blade for the spring arm. I drilled the original hole in the end of the saw blade so the screws could pass through. Then I sandwiched the blade between two brackets and secured it with a screw and nut. I used a cutoff wheel to shorten the screw so I could reach the other hole in the bracket when I mount it to the base.

The next step was finding the center of the poplar board that I cut for the base to mount the parts onto. I found the center and mounted the spring arm and the pivot base first. Once it was centered I drilled two pilot holes in the poplar and then secured the spring arm and pivot base assembly to the base.

Once the pivot base was in place I started finding the locations for the left and right contacts. I could have moved them a little closer to the spring arm to allow for more adjustment, but if I need less spacing I could change the 3/4″ screw for a 1″ screw. After attaching the left and right contacts to the base, I threaded one nut onto each screw and then placed the screws (contacts) into the brackets and secured them with another nut. At this point the Cootie was almost ready. Now we need to wire it up.

To wire mine up I chose to use three wires. If I wanted to use it like a single lever paddle I could. You could use two wires and a jumper from the left and right contacts if you did not plan on using it as anything but a sideswiper. For the SKCC, all code must be sent manually so to make this Cootie compliant with the rules I chose to use gator clips to short the two contacts together (as shown in the image above). I wired mine with the dots on the right side and the dashes on the left and the ground/common on the pivot base. I used a USB cable for my wires and connected it to my Icom IC-7300 according to the owner’s manual (page 18-4). A true cootie would only need a mono plug, but I chose to make it where I could use it for Parks on the Air as either an electronic bug (using the IC-7300 settings) or as a single paddle (again with IC-7300 settings).

Edit 11-19-2021:
After a long CW QSO with Rob, W2ITT, I decided that I should turn the screws around for the contacts and grind them to a point. I also mounted the wires under the bracket to eliminate two nuts. The contacts were developing some chatter or bounce, and I didn’t like it. I kept having to sand the heads of the screws, and I think this ultimately will solve the chatter issue.

2 thoughts on “Homebrew Cootie/Side Swiper”

  1. Nice work! I’m planning to build one for my mobile station. I use a KN4YB SW-75 cootie at home and at first, I was disappointed. My KX3 is quite fussy, so bugs and cooties often has scratchy contacts. Then, on a whim, I replaced the original nickel-plated steel contact screws with brass hardware. Boom, problem solved.

    One thing the SW-75 does well is to include an adjustable middle post. This serves to provide variable spring tension. I think I will incorporate that into my design. Also, stainless steel feeler gauges are a good source of blades, rather than scraping paint off of a hacksaw blade. They already have a hole in one end, which helpd. Harbor Freight has an inexpensive set. You can even double-up the spring if needed, much like the KN4YB cootie.

    1. I have a KN4YB bug that can be touchy at times. I thought about using feeler gauges on the cootie, but I thought that being able to saw hacksaw cootie would be cooler in those longer QSOs.

      Thanks for your comment! 73 -W1RCP

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