Tuesday, 27 December 2016

Seasonal Sporadic E

What  I like about operating on VHF is the opportunities it brings for sudden long distance contacts.

The down side of this is that you need to sit around for long periods in between bursts of activity.

This is especially true for what is sometimes called "Christmas Es". I fact it is more like "late December and early January Es", but that does not trip off the tongue so easily.

In fact it is very unpredictable, may not happen at all, and if it does come, it can arrive any time between the beginning of December and mid January. It is usually weak, short lived, but for those reasons, great fun if you happen to find it.

This year there was a sudden opening on "Boxing Day", known in many other places as St Stephen's Day, i.e. 26 December. This is close enough to Christmas to make the title just about accurate.

Most of us had been watching for a while, more in hope than expectation. In my case this involves the usual WSPR study of the 10 metre band. This is where Es springs from for me. If there is Es on 10m I look at 6m, if it is there is Es on 6m I look at 4m, and if it is on 4m I look at 2m, with each step getting less and less likely, but better in outcome if it does occur.

So on 26 December once 10m WSPR started to get very busy into the "near Continent", mostly PAs and DLs to start with, I moved up to 6m JT65.
10m WSPR activity from GM4FVM on 26/12/16. The more distant stations came at the end of the event.

6m JT65 was proving hopeless, with no takers at all. Then I noticed that Gianfranco, IU1DZZ, had posted on the WSPR.net site that 6m was open at his end. GF's posting got me thinking. Perhaps WSPR would work better than JT65 (which would happen if the signals were weak but steady). So I switched to 6m WSPR to find out.
6m WSPR activity from GM4FVM on 26/12/16.

As it became clear that 6m WSPR was well established I turned again to 6m JT65, and eventually to 4m SSB too.
4m and 6m log entry, see map below.
I was a bit surprised that this unseasonal Es lifted the MUF as high as 70MHz.

So this was a classic late Es opening. The good conditions lasted from 11:20 to 15:14 on 10m (around 165 spots), 12:00 to 13:20 on 6m (10 spots and 5 QSOs), and 12:57 to 13:29 on 4m (2 QSOs).
6m JT65 and 4m SSB activity from GM4FVM on 26/12/16
Hardly much to get excited about really, in the sense that nothing new was worked and these events do happen from time to time. But I really enjoyed the opening.

What does excite me is the unexpected nature of it all. Yes, I do get steamed up about these things.

4m was, as so often, very interesting. I worked 9A1Z fairly easily, though strong winds meant that my mast was lowered. Then I could hear GM4JJJ working some stations on CW, including what sounded like an OM or OK station, but I could not hear the other station at all. I called CQ and then, suddenly, SP6RLA popped up, worked me 5/9, and vanished. The event was over on 4m.

Es openings are always best just before they end. To work a station like SP6RLA (JO81, 1368km) out of the blue like that is typical. It combines the joy and pain of VHF working perfectly. I had thought that the 4m opening was over (wrong), but I was still calling CQ just in case. He was very strong. I heard no other SP stations, though I know other stations around me were working other stations in SP. I did not hear him working anyone else.

At times it feels as if VHF propagation provides a unique pipeline between me and the other station. It is so selective, especially as you move up the bands. By the time you reach 2 metres, where Es is fairly rare, you might just hear one station but none of the ones around that station, and nobody but you can hear him. Then the propagation moves on, and you might, or might not, hear another one.

It is this "either you work it right now, or it is gone" aspect of VHF which fascinates me. I suppose 20 metres must have similar attractions but I cannot see them.

So here I am on 27 December, with WSPR again running on 10m. Nothing is happening. In my experience of this type of Es (well, all Es really) the same thing does not often happen on successive days. But it might. You never know.

Why is there often Es activity in the depths of Winter, near the Winter Solstice? I do not know. Could it be ionisation from the Southern Hemisphere spilling over? I have never seen a satisfactory explanation.

Who cares about the explanation, it is fun to work.





  1. You are right Jim, I was called by a station that I thought was OM1TL but he was weak despite giving me 579, I could not confirm his callsign, I am fairly sure about the 1TL but QSB meant I just could not get the prefix at all. It remains a mystery.

  2. My mast was also lowered which means more noise from electronic devices around the home, especially computer displays.