22 January 2007

I-TASC expedition 2006/2007

Yesterday we decided we would like to try and improve the reception for a possible installation of the AWS in Gronehogna. We cant improve the transmitters, or the position of the base, so the next thing left to do is to try and improve the antenna. Tom and I mailed a few people to ask them to find a diagram online or some software for an antenna for the frequency we needed (900MHz). Marko responded by mailing an application that helps you design yagi antenna. So, not having done it before, we dived right in. Thankfully at hand was Remmy (my roommate) and he didn’t have much to do today so we went through the process of sourcing the materials we needed. At the bottom of the backyard here is a small radio orchard. It grows big HF antenna for measuring the depth of the earth’s atmosphere.

So naturally, Remmy and I figured this would be a wonderful place to start looking, so Remmy and I went down the back to see what we could find. Rumours have it that antenna elements have been known to ripen and fall off the big radio trees. Strongman Struan told us that he himself had been down to pick up some elements there just recently (Strongman Struan is a story in itself, the story would be longer but a few days ago he tied himself to a huge kite and the wind played unkind games leaving him with a broken leg and dislocated foot. He was lucky he had thought to tie the other end of the rope to the base, else he would have been blown over the cliff). We stopped by the first small grove to enjoy the sun and take some photos.

Then we pushed on to see if we could find anything interesting. It wasn’t long before we found a small antenna sprouting from the ice. That would have been good for what we needed but we decided it was best to let it grow in case the scientists found out that we had taken all the saplings and their measurements next year might not be as tasty.

Luckily it didn’t take long before we found an element or two lying about under the enormous electromagnetic branches, and most of them looked just about right. So we kept searching for what we could find, looking for the telltale long shadows they cast on the snow.

Remmy proved an expert at finding them and he quickly found many more than I did. I think in all he found about a dozen or so and I found one or two. I put this down to the fact that he has spent more time in this orchard than I and knew what to look for.

So we decided quite soon we had found enough and walked back slowly in the sun to home.

Next up was to cut and dice the found elements according to the pattern we had designed with the software. No problems. Remmy started in this while I went to look for something to use to mount the antenna. In the backroom above some stairs, there is a pile of unused junk. In the pile was a nice discarded piece of PVC pipe about the right length and width. I brought it back to Remmy and he was delighted, thinking it a very good find indeed.

Remmy measured and cut the elements we found and I marked the pipe with the right points that we would mount each element. We then went to drill holes in the pipe. Within an hour or so we had all the elements completed and the holes drilled.

Next up, we needed to start inserting the elements into the pipe at the right spots.

It meant we needed to file out the holes a little and by the time we had finished it was looking like a yagi antenna (but possibly not like the ones you buy in the shops).

We had to make the connection between the antenna and the cable which requires a ‘balun’ (short for ‘BALance UNbalance’).

So we taped the new antenna onto a bit of plastic pipe and Tom volunteered to run down to the airstrip on a Skidoo with one of the transmitters so we could test the antenna. Zama (cabin mate 2) was also on hand to give us his guru tech advice on the balun.

Within a few minutes, we could test it and it seemed to work! At first glance, it does appear to be quite a bit stronger than our original antenna but we will need to do some more comprehensive tests yet. Anyway, it was in interesting thing to do and means at the very least that we have now tried every possible thing to get the radio communications going the way we want them. Many thanks to Borja, Luta, Marko and Zama for their invaluable advice regarding building a yagi.

Any other news? I don’t think so… ah yes, there is a hippy living in a tent at the garden, but that’s not surprising I suppose since hippies like gardens.

Any other news? Not really…hmmm…I think the radio station round these parts sounds pretty good, you should tune in – 90FM i think…..no more news I think… oh yes, I have a beard (don’t worry Lotte, it will be gone before I get to NZ 😉

(Happy birthday Wayne!!!!)

Print Friendly, PDF & Email