My Dad's friend was scrapping a old lorry and he used to have a CB radio installed in the cab but took it out years ago but the antenna and mount was still in place on the side mirror. Attached to the antenna was small plastic cylinder. I asked if I could take them which he inclined, so I removed the antenna and accessories.
I have seen these small cylinders on CB antennas and at radio rallies before but never paid much attention to them. A search online came up "artificial ground" basically if you don't have a metal body on the vehicle place this between the antenna and mount and it will improve the SWR "so they say....."
Well I was able to remove the bottom cap where the SO-239 was to find small black toroid with a number of windings on. It looked like a choke more than anything! I had no use for this and hate throwing items away so will always try to repurpose it, so today decided the enclosure would make an ideal 49:1 transformer for portable use.
I already had FT82-43 and 150pf 3KV capacitors so got to work making the 49:1. There is plenty of info on the web for 49:1 but I followed the QRPguys version as I read about them recently.
The only tricky part was leaving enough wire so I could solder onto the ring terminal on the 3/8thread inside. I also used some hot glue to hold the FT82-43 in the center and stop it moving about when in my portable kit.
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| the new transformer |
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| All ready to push together |
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| Just need to find a nut for 3/8thread |
So if you come across old CB stuff, just before you decide to throw it give it another though you never know what you can do to give it a new lease of life!
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