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Tip: Throttle PTT ? Hiding the Wires

Ironflight

VAF Moderator / Line Boy
Mentor
Everything about building an RV-3 comes back to building it compact. So when we wanted to use a throttle-mounted Push-to-Talk switch on the Fat-Boy grip and DJM quadrant, I really had no room for a coiled cord ? heck, there is just enough room for the grip! The solution was actually pretty simple ? I used large (3/4?) heath-shrink tubing to hold thin (24 gauge) wire to the back edge of the lever itself. This necessitated some disassembly of course, but it?s not the first (or last) time the quadrant will probably be apart. The slot in the quadrant is precisely carved to be just wide enough for the throttle lever, so I had to split the heat shrink into two pieces ? on above the quadrant face, and one below. The wires are held firmly even with the gap. The only trick is making sure the wires stay put on the back edge while you shrink the tubing (without burning your hands?.).

I ran both a PTT and ground wire from the switch so I didn?t have to rely on the ground through the pivot bolt:
IMG_0519.JPG


Heat shrink above the quadrant ? some disassembly required:
IMG_0522.JPG


Heat shrink starts below the throttle cable attach point and stops above the pivot bolt:
IMG_0523.JPG


All finished (sorry for the fuzzy picture) ? wires exit at the pivot, so they have very little movement:
IMG_0524.JPG


Paul
 
Nice

Looks nice. I just did something similar a couple weeks back. You may want to pull the two wires into the casing of a larger wire prior to shrinking to give the conductors more protection from rubbing through where they pass through the quadrant slot. Shorting, grounding or pinching here could cause a stuck mike.

Bevan
 
That's a good point Bevan - you want to make sure that you do this carefully, or provide a way to "unstick" the Mic if it shorts when you don't want it to (a disable switch will do it). The other thing is to make sure that the throttle lever doesn't contact the back edge of the slot when you adjust the controls - make sure that the stops on the throttle end of the cable stop the travel before the wires get pinched.

Paul
 
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