8 Sep 2015

70cm contest using a 2m big wheel

Stations worked on 70cm tonight with 5W and a 2m big-wheel omni
This evening was the September 70cm leg of the RSGB's UKAC contest, so I decided to give it a go with my 2m big-wheel and 5W SSB. The match on 70cms was very good, but I had no idea how it would actually work. Well, the answer is "very well" as you can see by the stations worked. Best DX was 182km. To say I was pleased is an under-statement!  I shall be able to use this antenna again in 70cm contests. I was also able to copy the new beacon NW of Leicester GB3LEU which was pretty good copy on 432.490MHz.

2 comments:

Hugh said...

It is no great wonder the big wheel works on 70cm.. it is 3x the freq of 2m,
and is essentially folded dipoles, so should work fine.
At 70cm I would expect the radiation pattern to be basically 6 similar lobes instead of omni. I am a little surprised that all the big wheels I have seen are directly fed un-balanced with coax. Ideally, these should be balanced fed, with a 1:1 balun but nobody seems to do this?? G6AIG

Roger G3XBM said...

It would be interesting to see this modeled with an antenna simulation program. As the loss in the coax on 70cm is higher than 2m, any remaining lowish SWR is reduced at the TX.

Essentially it matched perfectly on 70cm, but I was unsure how it would actually perform. In reality, it worked pretty well on 70cm too: an ideal compromise antenna - good on 2m AND on 70cm.

The main beauty is not having to turn it: activity from all compass points is copied and the horizontal gain nearly as good as a small beam in the best direction.