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12m SpiderBeam Vertical Pole Antenna

I’ve really been impressed this weekend over the quality of 160m SSB operators who I found were courtious, patient and keen to accept my call. I’ve done single-band entries before on 40m where the tight frequency allocation and numbers of operators mean that there’s a pretty agressive tension in the air – not so 160m. There seemed to be space enough for the big runners to hold a frequency and enough of them to allow the casual Search and Pounce operator to have a couple of hours fun from time to time.

12m SpiderBeam Pole

Regular readers of this site know that although I’m a keen contest operator, I love building and testing antennas. This weekend allowed me to build something a little different to squeeze in a 160m vertical into my back garden where I only have 10m x 15m to play with (in old money, that’s only 30 x 50 feet).

Pictures tell a thousand words so I won’t go into the heavy details other than I used up the full 12m SpiderBeam pole and put up 8 radials ranging in size from 6 meters through to 12 meters (telephone wire, spare from an old reel). The Feedpoint was 2 meters off the deck and the radials were parallel to the ground. I fed it at the feedpoint with an SG-230 powered by a car battery housed in the shed. 30 meters of low-loss, double-shielded Westflex coax fed the tuner.

My only trouble was that after a few hours, the pole started to telescope into itself with the strong wind which required me to take it all down and hose-clamp (jubilee clip) each section after using liberal amounts of plastic tape so that I wouldn’t damage the fibreglass. SpiderBeam do a clamp-set with small rubber shields and if you are thinking of getting one of these, do buy the little clamp set, it’ll make your life easier. Even then, one of the sections moved a few inches in the night. It’s settled now – but you can see the vertical telephone wire that I used as the antenna has become slightly loose.

Results were quite encouraging and with only three or four ventures onto 160, fitting in dinner, bedtimes and some family TV, I scored 51 QSOs with the USA being the biggest potential DX. I didn’t work them though. My footprint covered the near Atlantic islands (Madeira etc), North Africa through East Mediteranean and up around European Russia and Finland. I genuinley didn’t believe that such a small antenna would work that well particularly at only 100w. I think getting all the RF into the antenna instead of wasting power heating coax may be the key here – and it’s the SG-230 that takes the blame for this :)

Final relaxed score was 51 QSOs, 24 Countries for 6,144 points.

REF Contest: Not content with one contest this weekend, I also entered the REF contest. Conditions were terrible though. I’ve had much bigger runs into France on 40m but not this weekend. It kept me out of trouble but certainly nothing to write home about. 20m was off the score card because I could rarely find any propagation into France on 20m – the same on the higher bands too.

It did give me a chance to use the vertical though for general purpose DX and occassional tests with James (M3YOM) who had also put up a similar antenna this weekend – also using an SG-230! For me, some mixed results although the vertical normally won the competition barring 80m where the higher levels of radiation inter-UK suited the full-wave NVIS loop better.

I’m left with one question: Why did the vertical work on 160m locally – but not on 80m locally where the loop was required? There’s some propagation going on here that I don’t understand. More experiments are required.

Overall though, a great experiement though.

Cheers and beers.

Callum.