The Australian Terlin Outbacker antenna has been a stalwart of HF mobile communications since time immemorial. It’s a sturdy, adaptable, vertical antenna that can cover the entire HF spectrum by plugging a flying lead into one one of a number of sockets depending on the band of operation. It also has an adjustable top section, colloquially known as the “stinger”, to tweak the resonant frequency on the selected band.
The Problem
While the Outbacker antenna is solidly built, it’s not completely indestructible, as Dom VK2JNA learned recently. The stinger of his Outbacker Outreach500 antenna had snapped off and when he tried to rescue the part of the stinger left inside, it moved further in and could not be extracted.
Dom put the problem to the Manly-Warringah Radio Society Brains Trust™ for suggestions on getting the broken stinger out of the antenna. Here are a few of the ideas we came up with…
The Suggestions
- “Centrifugal force – attach the bottom to a rope and spin it around about your head. Before starting, make sure you put a lose PVC electrical tape at the end to capture the stinger when it shows up. WARNING, could become a projectile, both the aerial or the singer wanting to come out.”
- “Accelerated gravity – put a cork or similar material at the top to protect the aerial and capture the stinger. Drop the aerial top down from height, ensuring the corky device hits the floor first (you may need a carboard tail like a inverted rocket to ensure the back stays up-right on the descent). Start from a lower height and increase as required. WARNING, this could break the aerial when the TOP height is reached.”
- “Following on from the accelerated gravity if you can produce a shock to the antenna the rod may start to come out.”
- “If you have an idea how long the broken piece within the antenna is you could drill a small hole below that then push a suitable size tie wire in the hole and push out the broken bit.”
- “Would it help to insert something to splay out the “jaws” that holds the stinger, and apply remedies other have suggested?”
- “Providing you have the right equipment and the threaded bit is “drillable”, you could drill a small hole at the bottom and push it from the bottom … using another stinger! However, so far, Terry Clinch (manufacturer) has suggested not to drill as the windings are in there. I believe there is a hollow (as I have pushed the stinger all the way in previously).”
- “Another way would be to cut a slot across the metal tubing and lever the stinger up with a small screw driver, just like a gate bolt or door latch.”
- “Instead of drilling into the antenna, how about (while you have the antenna upside down in the vice), holding the drill body against the antenna; perhaps the vibration from the drill might coax the stinger to move back towards the tip. Some hammer drill action might prove effective.”
- “If all else fails, just push the rod down the middle of the Antenna and leave it there. This may change the tuning a small amount. The further down the antenna the less the effect. If it does not go down very far some shorter tuning rods will still work.”
- “Carefully select a spot and drill a 1mm hole at the base and use an air compressor.“
The Attempts
Drilling into the side of the antenna would have been problematic, risking damage to the wire that coils up internally. Also, knowing exactly how far down the end of the stinger piece was would likely involve drilling multiple holes. Dom takes up the story of the attempted fixes:
Initial Attempt
Inserted something to splay out the “jaws” that holds the stinger, and applied some of the remedies suggested. Stinger has dropped below the area where the jaws are. I had splayed them so they would not be part of the problem however it seems a bit jammed further down. Jaws split are about 5mm length. Stinger is about 12mm in.
Attempt 2
As can be seen below, I have attached G-clamp. I have been belting the clamp against vice downwards but stinger has not moved!! This suggests magnets are way out of the equation. It seems well & truly jammed. I am also in conversation with Terry Clinch (manufacturer) but will only go down that path of return to shop if we cant get any headway here.
The Resolution
I drilled a 5mm hole but just enough to get through bottom socket. The hole was just deep enough to get through the brass but no further. Terry Clinch (of Terlin) warned me not to drill beyond the brass into the fibreglass as it may damage the windings.
Using the new long stinger held in a vice, I kept tapping the antenna towards vice (like the improved accelerated gravity suggestion but from other end), pushing the broken stinger up back out through the top.
I have cut a new stinger at 46″, re-assembled, tuned & checked. All is ok!
Contributors
Thanks to the Brains Trust:
Clifford VK2CLF
Colin VK2JCC
Dom VK2JNA
Geoff VK2WA
Ian VK2DAB
Peter VK2WPJ
Phil VK2BDF
Richard VK2SKY
Russell VK2BYN
Yves VK2AUJ
…and special thanks to Terry Clinch of Terlin for his assistance and invaluable knowledge of the Outbacker construction.
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