Fixing a Telescoping Antenna for an RC Car

Recently, I passed one of my Kyosho Mini-Z RC Monster Trucks (AM 27 MHz version) on to my son, who recently turned 7. He enjoys playing with it, but like most young kids, he does not really know the proper care of the truck. As he was keeping the antenna, he pushed it in with his palm instead of pulling the segments in from the base (my fault for not teaching him that). The result was a broken antenna, near the base of the second top-most segment.

To remove the two top-most segments, I simply took a screwdriver to the third-segment, and pried it open a bit. This allowed me to retrieve the broken part as well as the copper plates that was inside. As described in the caption below, the copper plates limit the movement of the antenna segments, and are critical to proper function.

Telescoping antenna are prone to bending and breaking if mishandled. They consist of segments that have, at their base, two copper plates that have a small protruding portion (that extends into the segment’s lumen, and stops the next smallest segment from collapsing too far), and the copper plates make the base a bit thicker than the main diameter of the segment, preventing them from over extending (top image). In this case, the antenna broke close to the base of the second segment (bottom left), and I had to drill new holes in the remaining portion of the segment into which the copper plates’ nub will be fitted.

After drilling new holes in the remaining part of the second segment (a little too far from the edge, but as I was freehanding the Dremel, I didn’t want to risk tearing the bottom of the segment) and putting all the segments back together, the challenge was to somehow roll the top of the third segment inwards, to prevent the newly-fixed second segment from being over-extended.

Using a plastic model sprue cutter, I press the end of the third segment inwards (left). However, even the small gap seen here is too big, as the copper plate threatens to slip through when pulled out too vigorously.

While I had some success bending it back inwards with a sprue cutter, the tolerance for this part is actually very small, especially when one considers the force an excited child might exert on the segment when extending it. So, I had to go much further than this, and really bend the tip in (a bit too much) and get it back to round-ish by forcing the segment out.

Fully-retracted, there is some gap between the top two segments (left). This is roughly the length that was broken off. As the segments are extended, there is practically no gap between the diameters of the top two segments.

After finally completing the fix, the antenna is almost good as new, much to the relief of the culprit, who can be seen in the last photo. 🙂

4 thoughts on “Fixing a Telescoping Antenna for an RC Car”

  1. […] Whether it was as an impulsive youth or an impatient adult, there’s probably few among us who haven’t broken a telescopic antenna or two over the years. It doesn’t take much to put a bend in the thin walled tubing, and after that, all bets are off. So [The Amateur Engineer] couldn’t really be too upset when his son snapped the antenna off the transmitter of an old RC truck. Instead, he decided to take it apart and see how it could be repaired. […]

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  2. […] Whether it was as an impulsive youth or an impatient adult, there’s probably few among us who haven’t broken a telescopic antenna or two over the years. It doesn’t take much to put a bend in the thin walled tubing, and after that, all bets are off. So [The Amateur Engineer] couldn’t really be too upset when his son snapped the antenna off the transmitter of an old RC truck. Instead, he decided to take it apart and see how it could be repaired. […]

    Like

  3. […] Whether it was as an impulsive youth or an impatient adult, there’s probably few among us who haven’t broken a telescopic antenna or two over the years. It doesn’t take much to put a bend in the thin walled tubing, and after that, all bets are off. So [The Amateur Engineer] couldn’t really be too upset when his son snapped the antenna off the transmitter of an old RC truck. Instead, he decided to take it apart and see how it could be repaired. […]

    Like

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