Sunday, 4 October 2015

At last, a decent VHF opening.

I have not forgotten you all, it is just that I am having dire rotator problems, more of which anon.

Since I moved here there have been perhaps 2 reasonable tropospheric openings. I mean the sort of thing which in the 1970s arrived every couple of months. A high pressure system moves in off the Atlantic and gets stuck over the North Sea or Scandinavia. It then sits there for four or five days, giving a widespread VHF opening over North West Europe. Here that means the local repeaters become full of people working on oil rigs in the North Sea, or captains of Icelandic trawlers, working with handhelds and reaching surprised locals driving along the road from Selkirk to Peebles.

Surprised locals of course, because otherwise the repeaters in this region are virtually entirely unused.

So we have just had such an opening. I might as well go over it all as it is such an unusual event.

As a reminder I do not have a very fancy 2m station, IC7100, Microset linear 200W peak, 10 ele at 10 metres. On 4m it is the same rig and a TE Sytems linear, 100W peak, and a 6 ele yagi.

On 27 September we had the "Practical Wireless" 70MHz contest. I worked 8 stations and nothing particularly remarkable was apparent.

By 29 September the pressure was about 1026 and rising. The RSGB 70MHz "UK Activity Contest" was more lively than usual. I worked 15, reaching G0HEL in IO81, which is 510km. Interesting, but hardly my best DX in these contests. Still, as the RSGB contests are often held at times when the conditions are poor, this was not bad.

By 30 September pressure was tending to 1028 mb (it reached 1032) and I worked OZ5AGJ in JO55xe on 2 metres SSB at 14:07. Once again not great DX at 678km, but loud 57 reports both ways. OZ on 2 metres is DX in my book. From that point until 3 October I could hear one or more Swedish beacons, SK1 (or 6 or 7)VHF. Then at 20:24 came OZ6TY (JO55 890km) and at 22:26 SM7GVF (JO77 1029km).

I like them all, but once they go over 1000km, I like them more.

Despite many attempts by me to raise anyone on 4 metres, this was a 2m event here. I heard some 4m beacons, but no contacts resulted.

The Hepburn Tropo Index site can be very useful in these conditions. Updated every day at about 18:00, for many many years this very handy site translates forecast weather conditions into propagation predictions. OK, you could get something similar from a weather chart if you knew how to interpret it, but Hepburn's chart does all the work for you. You can jump forward by clicking it, for about five days, with more regular updates for the next two days, and more general predictions for future days.

Here is the Hepburn chart for 1 October.

You can see the effects of the high pressure centred somewhere over Denmark by that stage. To work tropo you tend to do best by beaming to one side of the peak high pressure, so in this case Northern Germany looks like a good bet, though sometimes right through the middle works too.

Tropo openings are usually quite different from, say, Sporadic E ones. With Es you are using a small area of ionisation midway between you and the dx to reflect your signal. Therefore you hear only one station, or a few grouped together (that is a huge generalisation, but roughly true). With tropo you need to have the high pressure right along the path you are using (again a generalisation), and you need to be under the raised pressure and so does the dx station. That means that generally you hear stations all around the high pressure area.

A troposheric duct is a bit different, as it is more like a tunnel between you and the dx, where you only hear a few stations.

This looked like a classic tropo system, but actually it worked more like a series of ducts, and I was hearing a few stations at a time, and the area covered was moving around. Mind you, it did last four days so it would move a bit.

On 1 October I started off working DL8VU (JO54 814km) before working 3 more stations in Germany and one in Sweden. Best dx that day was San, DD3SP (JO72 1131) who I have worked now on 6m, 4m and 2m. San was best dx of the whole event for me.

On 2 October I worked Marek SP1JNY (JO73gl 1101) - a part of Poland closer than San's part of Germany. Then it was 1 Netherlands, 5 Germany, 1 Sweden.

By 3 October the high pressure was drifting away. I heard more Germans and Swedes, and beacons in both, but no contacts resulted.

This looked like a classic tropo opening, but it was not quite like that. The area of high pressure was further North than usual, so the normal opening into Netherlands, Belgium and France did not occur. Also, it was pretty localised and moved about a lot. Still, Denmark, Germany, Sweden, Netherlands and Poland are not everyday fare here. I am happy with that.

Best of all of course was a series of rag chews with Rob PA3GFY, David GI4SNA, Robert GM4GUF, and others. Whatever dx there may be, these long rambles are always interesting. And when I was blethering with John GM4EOU across the Firth of Forth in Cellar Dyke, DL8VU chipped in for a 3-way contact that lasted almost 20 minutes. There was more QSB on the path to Cellar Dyke (there usually is none!) than there was to Germany.

And thanks go to Chris GM4ZJI whose constant helpful SMS texts and phone calls kept me on the path of the dx.

Yes, I heard LY2WR in Vilnius KO24fo 1861km but not quite strong enough for a QSO. So a new DXCC heard but yet to be worked.

All in all a great few days. I know tropo is best in the early evenings, but I managed to still have a time to sit in front of the TV in the evenings, and work some DX.

Back to normal today (4 October). Meteor scatter with SP9HWY on 4 metres. Now, this I enjoy too - 1538km is more like the thing really. Big openings are just great, but working an old pal miles away  is good too. Just as well, as flat conditions are what we have most of the time. And now I hear SP8SN which would be a new square if he could hear me!

Will it be years before the next tropo opening? I suspect so.

Am I bothered? Not really.



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