I saw Dom Bragge's posting about a 2m J-Pole antenna made out of 300 ohm TV ribbon and thought I'd give it a go.
Although the design specifies 51 inches in length, Dom notes that other builders have found this resonates too high in frequency and they suggest you start at 52 inches. I did that but found that the lowest SWR was at 148Mhz so even that's too short.
Perhaps 300 ohm twinlead material is different to the original designer.
I do have one contribution to make on this topic, it's really hard to strip the insulation from this twinlead. The insulation seems very strongly bonded to the conductors and they always rip out for me. The solution is to melt your way through with a soldering iron.
Some toxic vapour comes off but it seems pretty easy to tin the wires after the plastic melts away. Shown above is the bottom of the antenna where the co-ax connects and the shorting bar at the base. The melting works quite nicely as you can see.
Thanks to Dom for the pointer to this simple and highly portable VHF antenna design.
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