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Old 13th Jul 2007, 8:31 am   #1
Mike Phelan
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Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
Posts: 4,609
Smile A tale of two aerials

I thought it might be interesting to let you see how I repaired two broken Hacker aerials that I fixed for Howard.
As found, aerial #1 had come out of its tube completely and broken, the knuckle was not visible, but all the sections were intact.

On #2, the rod just pulled out, as did the innermost tube, which looked to have about 15mm broken off the bottom end.

The aerial is constructed with two bronze half-shells that are attached to the bottom end of each tube. These form a bearing, and prevent the tube from coming out of the top of the next outer tube, whose end is closed in at the top.
The bottom of the tubes have two holes, where a “dimple” on each half-shell locates it, and forms a stop for the next inner tube.

#1 first:
I pushed a rod through the tapped hole at the bottom, so the knuckle could be brought out of hiding into position at the top. The broken outer tube had about 10mm attached to the swage on the knuckle, so I cut the remains off. The aerial can all be dismantled by unscrewing the top and pushing each tube out, starting with the rod. Note that each pair of half-shells is unique!
The outer tube needed the bottom end squaring up on the lathe.
After reassembly, I used Loctite 601 bearing fit to attach the outer tube to the knuckle (first time I have tried this). After leaving it for 2 hours, it seemed to be fine with a bit of pulling and pushing.

#2 (picture below)
I had to cut the outer tube to dismantle it – a piercing saw with the lathe in slow backgear is my preferred method, and leave a perfectly square end.
The inner tube remains were still there, but the half-shells from the rod must have fallen out sometime. Dismantled it all first.
I squared up the end of the intact part of the tube and drilled the two holes for the half-shells.
This meant that the end of the rod was much too far down, so I drilled another cross hole in it, but left the excess length of the rod there for stability.
I needed something to replicate the half-shells now. From a piece of the broken tube, I cut it off to about 8mm and slit it so it could be closed up on the rod. It would not go into the tube, so needed filing, gripped in a pin vice. Once this was in, a brass clock pin was driven in to retain it, and the end cut off so the rod would go up into the tube.
Success!

One point here, when these have been repaired: as the outer tube is always going to be about 8mm shorter, it will push below the casing when you close it up. This could be avoided if the screw that retains the solder tag is made a bit longer; this does mean that the next inner tube will always project a little, though.

A bit of advice – don’t throw any scrap aerials (car or domestic) or any of these telescopic magnet thingies – tubes are useful for aerial repairs!
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