Before we start, be aware that this mod will disable knobs on the radio. One knob will be disabled for every slider you add.
Step 1: Collect Parts and Supplies
- Hot glue
- 2 10kohm linear slider potentiometers (This is the one I used.)
- Wire cutters/strippers
- Hook up wire
- Screwdriver (Philips)
- Dremel/similar rotary tool (with a bit to cut plastic)
- Soldering iron and solder
- Something to score plastic with
- (optional) superglue
- (optional) liquid electrical tape/shrink wrap tubing
Just a note, do not use logarithmic sliders for audio, they will sort of work, but any sort of useful control with them will be nearly impossible. Make sure you get linear potentiometers.
Step 2: Figure out layout
Before you pull the transmitter apart, take the time to hold it, figure out where you want the sliders to go, remembering that you cannot put them too close to other switches or the knobs. Also, decide which knob(s) you want to replace with the sliders. Once you figure out where you want them, take the screws out of the transmitter and open it up.
Like me, you may find that the sliders will not fit exactly where you wanted them before you opened it up. Shift their location around and slide the two halves back together if you have to so you can get a feel for exactly where you are putting them. Here is how I finally ended up positioning mine before making any cuts.
Step 3: Install Sliders
Mark the shape to be cut out of the plastic so the sliders can be slipped into place. I just used the corner of a flathead screwdriver to do it, but anything with a sharp point should do.
Once the holes are marked, use the Dremel to carefully cut out the plastic. Take it slow, and clean off any burs of plastic that may form (especially on the outside of the case). Once that is done, it should look something like this (before it is cleaned up at all).
After the holes are cut, test fit the potentiometer to make sure it will fit. If needed, sand or cut more plastic out until it is a good fit. After the fit is good, put it in the hole exactly as you want it. Also, this is where a couple drops of superglue might be helpful to hold it in place, just make sure you do not get any inside the potentiometer itself.
Step 4: Make electrical connections
Once the potentiometer is securely in place, undo the wires from the knob you want the slider to replace, making a note of which wire went where, they do not seem to follow any convention. This side is normal, but the right side on mine had white as positive and red as the center wire. With the potentiometers I used, pin 1 is positive, pin 2 is signal, and pin 3 is negative. Here is what it should look like; I had to extend the wires a bit to reach.
Unfortunately, even though this would be normal for something like this (red positive, black negative, white/yellow center), it turns out that the radio was not following any standard. When I brought the slider to the bottom position, it would shut off. Luckily there was no damage, just open it back up and swap wires and it worked. Pay attention to where they came from the knobs and use that to place them on the slider (center should be on pin 2 no matter what color the wire is).
Step 5: Finishing up
No project would be complete without hot glue, so use some to fill in gaps between the plastic and the slider. It also should create a nice bond between the case and the slider. Mine looked something like this just before I closed it up.
Close the radio up, put the screws back in and plug a battery in.
Finally, the new sliders need to be calibrated, go to the calibration menu and follow the instructions there. It should give you a full range once they are properly calibrated. And after calibration, they are ready to use.
Enjoy the new slider potentiometers. To use them in programming, just put whatever knob they are replacing in the mix. In my case, they replaced P1 and P2.