Sunday 14 January 2024

At last a decent tropo opening plus 40MHz awakes.

Firstly I should mention that after a long lull during December and early January, some F layer activity has returned to 40MHz. As I start writing this on 13 January I have been receiving ZF1EJ at up to -4dB on the second day of good propagation this year. Let us hope this is a good start to the year, and maybe DX will reach 50MHz too before long.

My last posting was a whinge to complain about pretty flat conditions lasting 69 days. Well, eventually, after 86 days in total a reasonable lift started at last on 10 January.

It had been well signposted in advance. Both of the tropo predictors from Hepburn and F5LEN (see sidebar for links) predicted good conditions for 11 and 12 January 2024.

Hepburn Tropo Index for 18:00 on 11 January 2024

F5LEN Tropo map for 18:00 on 12 January 2024

Click to enlarge images if you need to, as usual. I like F5LEN's view of a misty field to represent high pressure.

Based on the maps I expected things to open mainly towards Sweden and perhaps into the Baltic. It started that way but most of the activity was to the South East.

Anyway, along with my FM warning system bringing in the Norwegian coastguard, I worked OZ1BEF on 2m at 14:24 on the 10th. This was followed by LA6GKA, but after that things generally moved away from that direction.

Over all, between those first QSOs and 10:00 on Saturday 13 January I made 98 contacts on four bands, reaching 38 squares and 11 countries. Best DX was on 2m to Olli DH8BQA thanks to his remote station in JO73, a distance of 1093km.

2 Metres

On 144MHz this was the result:-

144MHz contacts at GM4FVM 10 to 13 January 2024
This was the result of 43 QSOs to 10 countries. During events like this I tend to migrate to higher frequencies and simply keep a watch on 2m for anything interesting. In pure DX terms there was nothing very surprising with most QSOs around 800km. Notably absent were contacts to Central Europe, but I am not complaining. Not much anyway.


Spending my time on 70cm produced a few more contacts there than on 2m.

432MHz contacts at GM4FVM 10 to 13 January 2024
46 contacts to 25 squares in 10 countries with the best DX being to F1RJ in JN18 at 888km. The fact that there were more contacts on 70cm justifies my policy of concentrating on 432Mhz, or at least it does to me. OK the peak DX is not as far, but the average is not very different. 70cm produced a new country for me - Faeroes. I had heard OY9JD on 2m but I did not try a contact, after all I have worked him before and all of Europe wanted to contact him. So when he came up on 70cm I had to try for a new DXCC. Not only was IP62 a new square on 432MHz, but so was IO62 which was gifted to me by Roger, EI8KN. So pretty good on 70cm.


On 23cm things worked out rather well.

1296MHz contacts at GM4FVM 10 to 13 January 2024

Although this does not look very dramatic, it is a good performance for a microwave band. 8 QSOs in 4 countries with 6 squares. However, each QSO took some organising. I logged on to the Microwave KST chatroom. Although I rarely ever use the other rooms, the microwave one works quite well. There is time to set up a QSO and work your way through it with your companion amateur. 

I had worked Roger, EI8KN on 70cm and asked him to join me on 23cm. This was something we had discussed at the GMDX Convention in Stirling last year. I had explained to Roger that I had not yet worked EI on 1296 and he offered to help. At first we tried aircraft scatter but that failed. At a distance of 527km that should be possible but the window into which the aircraft have to fly is very narrow at that range. In the end we had to give up and this was the next attempt 3 months later. And it worked this time, so thanks to Roger for QSYing and waiting for me.

One 23cm contact stood out as odd, simply because it was "normal", or perhaps "random".  I sometimes call CQ at various beam headings, though this almost never works on 1296MHz. Still, you never know. Three minutes after I stopped calling, up popped DK1VC in JO31 also calling CQ. I decoded him at -03db and he gave me +01dB. What a splendid thing to stumble across a QSO on 23cm. It does happen, but not often at 811km. I was still hearing him 40 minutes later, but he only seemed to work one more station.

My other 23cm contacts were more normal, having been arranged via KST. I had tried to work Walter, DK3RV, on previous occasions but kept failing to make a QSO at 771km. This time I could see a faint trace on the FT8 waterfall. Often during a tropo opening the QSB can be very severe, so we kept at it and eventually after about 5 minutes I decoded Walter's CQ at -18dB. He responded next period with -19, then my RRR took another five and a half minutes to get confirmed, but the QSO was then complete and I sent 73. JO31 would have been a new square for me had DK1VC not provided it for me the previous day.

After my contact with Walter, it was the turn of Maurice F6DKW in JN18 to suggest a contact. Maurice suggested CW, and he agreed to try even after I told him that my CW is dire in the extreme. He was wise enough to QRS and once I had got the beam pointing the right was the contact was easy, 559 copy at  840km.

Later, after completing with EI8KN, David G4YTL from IO92 asked me for a QSO. M0CTP joined in and we completed using Q65 as FT8 was not up to the job. M0CTP and I were able to complete via aircraft scatter. Currently I cannot get planes to display on Airscout, which makes it pretty useless. Gary confirmed that it is the same with him, which was helpful information. I can stop trying to find a solution in the settings here. There may be some other problem with Airscout.   

It was a similar thing with DJ8MS at 903km in JO54. I posted that I was about to go QRT and anybody who wanted to try for a contact should reply. Tor let me know he would like to try and after struggling with FT8 once again we switched to Q65 to complete the QSO. I had also tried to work Tor using FT8 on previous occasions. Once we were on Q65 the QSO was easy.

So what are the learning points from all this for 23cm operation? 1) KST is not always essential but it certainly helps. 2) FT8 is not great on this band, but CW and Q65 can get you out of a hole. 3) It is worth asking people to QSY from another band. 4) CW has a place on microwaves, even if it is slow.


Tropo also helps on 70MHz. I was pleased to work Henning OZ1JXY with good signal reports. This is a series of QSOs which goes back a long way with well over 100 contacts via a variety of propagation methods.


After the end of my activity on 11 and 12 January I expected it all to be over but there was one more DX contact to be made. On 13 January at 09:30 I worked F5RZC in JO10 on 144MHz, a handy enough contact at 642km. After that the DX faded and the stations in IO82 and so forth reappeared after two days absence. It is funny how during a tropo lift you lose the nearer stations as well as hearing the distant ones. At the end I could also hear stations in IO90 etc who would have been nice for me to work, but they were all beaming south to work into F and EA. And that was the end of that.

If we neglect the one-off contact on 13 January, all the activity was between 14:24 on the 10th and 19:35 on the 12th. I only worked seven stations on the 10th, and at that stage it was looking very much like the Scandinavian opening which the maps had predicted. There were no distant DX stations (though I heard an HB9 a couple of times), none of the OE, OK, or EA stations I have worked during previous events. I am happy enough though. Once I could switch between 2m and 23cm using my IC-9700, working one and listening on the other, and at the same time use my IC-7100 for 70cm, there were stations on all bands and I was a happy camper.

I called CQ a lot of 23cm SSB, but almost all contacts were on FT8, with three on Q65 and one on CW.

You do not appreciate the good times without living through the bad times, as I often say.

2m now = 45 DXCC and 247 squares

70cm now = 20 DXCC and 99 squares

23cm now = 11 DXCC and 32 squares

I enjoyed those good times.

Thanks everybody for making the contacts with me.

Let the good times roll.

73 Jim


Sunday 24 December 2023

Longer days and Winter doldrums

I write this on 24 December, and I am really looking forward to longer days.

Today at GM4FVM sunset is scheduled for 15:37. That makes for a day length of 6 hours and 59 minutes. I should grateful for the two seconds we have gained since 22 December, but I prefer to think about the hours we will gain in future months.

Why does this matter to amateur radio? Well, the energy which causes ionisation comes from the Sun. The longer the Sun shines each day the more ionisation. Some features we rely on need a lot of energy, so F- and E- layer propagation usually occurs at times of longer day length. Cross Equatorial propagation modes benefit from balanced day length on each side of the equator and thus they tend to happen mostly at the equinoxes, whereas DX within the northern or southern hemisphere usually occur at times of longer day length nearer the summer solstice.

And not much happens in the winter.

Of course these are generalisations. Today on 50MHz there has been a short burst of "Winter Es", sporadic E propagation which often occurs around the Winter Solstice, i.e. roughly around Christmas.

50MHz contacts at GM4FVM on 24 December 2023

Not bad for just over an hour and a half of work. 10 QSOs to 9 squares, best DX 9A2DI in JN95 at 1870km. The trick is to watch out for this type of propagation sometime during December and January, so an hour and a half is not quite correct. I have been waiting for a few weeks now.

Then, later on 24 December, there was a Trans-Atlantic opening on 6m which missed GM4FVM almost entirely. I heard K9RX and that was it, apart from seeing weighty amateurs further west working a stream of stations along the Eastern coast of USA and into the Caribbean. You win some and you lose some.

Of course there are VHF propagation modes which are not affected by the season. Usually on 144MHz and above we have a series of passing high pressure systems which produce tropospheric propagation, plus the odd aurora for the lower bands.

Here is my 144MHz map since 12 October 2023. As usual click to enlarge images if necessary.

144MHz contacts at GM4FVM, 13 October to 24 December 2023

This does not look too bad for 2m, until you consider that it took 69 days to achieve it. In fact, it looked a lot worse until in one day I worked two French stations and EA1U in IN83 at 1389km who was the best DX. The other 68 days were very uneventful save for 5 November. On that day an aurora brought M5AGY, G4ILI, G0JDL, G4MCU and (best DX) G4XDZ in JO01 at 544km. All five contacts were over 400km. 

That aurora brought me on to SSB, a mode I seem to have lost the knack to operate. Although those 5 were on 2m, I also worked Gerry GI4OWA on 6m. I failed entirely to recognise him. It is now so unusual for me to hear callsigns spoken that the old familiar ones no longer trigger my memories. Ah, the joys of data modes.

Perhaps I should add that my hearing is not great. I gave up on the aurora after a station called me repeatedly and I simply could not decipher their callsign. I could blame this on my advanced old age, but to be honest I have never been good at decoding distorted SSB or even CW during an aurora.

Anyway, if you subtract those two days, the one tropo opening and the one aurora, 2m activity has been pretty woeful. The usual passage of weather systems has just brought a variety of low pressures, followed by lower pressure systems. The one extended period of high pressure (when I worked EA1U) was accompanied by strong winds which pretty well cancelled out the whole enhanced propagation. High pressure and strong winds - frustrating.

70cm was worse.

432MHz contacts at GM4FVM, 13 October to 24 December 2023

7 QSOs in 69 days. Best DX was to F4FET in JO00 at 627km. Although I have worked Gil on 2m, that was a new callsign for me on 70cm, also worked during the one high pressure period, despite the wind.

Now I have to make this point clear. All the contacts, even the local ones, are welcome. However, rarely have I experienced such dire conditions on the higher VHF bands. Usually I can rely on a nice stable (and not windy) high pressure to settle over the North Sea during this period of the year. My usually reliable contacts into Denmark have not happened so far this Winter. 

23cms was even worse again. I was away during the November activity contest but I came on for the December one. And during that 23cm contest I heard nothing. Even the NGI beacon could not be decoded. I did hear the Central Scotland beacon in Kilsyth, but could not decode it. Conditions were absolutely dire.

There seems to be another issue. I suspect that the novelty of FT8 on 2m has passed, and now only DX-ers turn it on. That means that there is only activity when conditions are good, and that was at no time during those 69 days. Quite a few of the contacts I did have were on SSB during activity contests. Sad to relate, many GM stations seem to have given up on UK Activity contests as they tell me that they have no hope of winning or even doing well.

So there you have it. I hope that we have reached the bottom of a long decline on the higher VHF/UHF bands, and hopefully longer days will bring better conditions on the lower VHF bands. I cannot be sure of a high pressure system coming along soon, but I can be reasonably sure that the day length will steadily increase, for a six months or so anyway.

Have a Merry Christmas and see you all soon.

73 Jim


Saturday 2 December 2023

6m DX in the Depths of Winter.

Depths of Winter?

Not quite.

"Christmas comes but once a year". Hmmm.

That is the title of a cartoon and is often said. Sadly, nowadays Christmas seems to start mid November and run for a least thirty days. Thirty Christmases with tedious Xmas advertisements on the television and carols and Christmas hymns on the supposedly "classical music" radio station often running in the background at GM4FVM.

I do actually like carols and hymns at Christmas, BUT NOT IN NOVEMBER.

A white Christmas? Scrooge-like GM4FVM is not keen on snow at any time of year. It freezes up the winches on the mast and locks the sections together so that the masts cannot be lowered without swinging the coax about wildly.

And then December started and on the first day of the new month the temperature fell to -7.3C and it started to snow ...

Wintry scene at GM4FVM on 1 December 2023

I do not associate VHF DX with snow. Years of being hooked on Summer Sporadic E (because of the lack of anything else) have taught me that VHF DX involves sunny days, high pressure and .. well ... Summer.

If anyone had been expecting F2 propagation on 6m they might have said to me that if I just have confidence then DX will surely arrive, snow or no snow.

Here is my 6m activity between 27 November and 1 December

Contacts on 50MHz at GM4FVM, 27 November to 1 December 2023

Click on the image as usual to enlarge if necessary. 

As it states on the screenshot, this is in fact up to 12:04 on 2 December. In the morning of 2 December I have already been calling PZ5RA who, despite being strong with me, cannot hear me. Another new DXCC on the waiting list. No activity on 2 December  ... yet.

Not bad for mid Winter - 16 QSOs to 9 countries. Best DX - 9447km. This is just the ones I worked, the list of failed contacts is very long and includes CO, HI, HP, XE and PZ amongst others. There have been openings on each of three days in a week, and in each case the pile-up from Europe was huge. I often listen and on the other period there was a wall of decodes with perhaps seven or eight European stations chasing each DX callsign.

At some stage I reckon that it is not worth joining the throng trying to reach these stations and I pick my moments rather than flogging on trying for the popular ones. Later I just called CQ and had a few interesting replies. With my 200W it is often the case that I can do better appealing to stations who can hear me than calling superstations who will never receive my call. Things began to look like 20m and I am not going to get involved in that rat-race.

Other stations just call CQ continuously, which I regard as a waste of time. To me that is counter-productive when it comes to having contacts. If they want to cut out half the DX, then they are welcome to spoil their chances.

50MHz on DXMaps on 1 December 2023

This looks like F2-layer propagation to me. It surely cannot be multi-hop Es as I have never seen that outside the peak summer season. It also did not sound like Es and there was no sign of the pronounced narrow propagation bands you get with Es. Signals were not as strong as Es and were quite stable. Also, three days openings during a five day period does not look like the Winter Es we sometimes get - not that I have ever seen transatlantic propagation with Winter Es.

I think this is the "classic" East-West F2 propagation I have been waiting for. The SFI on that DXMaps image is 167, and interestingly there was a geomagnetic storm underway with K=6 at the time. That storm was not creating an aurora here and the Bz component near here (from GM4PMK's magnetometer) was positive. Thus I think that the storm was not as significant in a radio sense as it might have been.

Solarham reported on 2 December that the storm had a positive Bz which would not help "the cause" i.e. bad for aurora and good for everything else. He then pointed out that a coronal hole should be Earth facing and the results might be here by 6 December. More mayhem on the way (possibly).

So I think that was F2 propagation. Still a bit too early to be absolutely definite but it looks that way. The sunspot number is still lower than the books say would promote F2 propagation (SSN 123 smoothed, 105 current, when I last looked)  but the evidence is beginning to mount.

Having ruled out Es from my reckoning, there has been a lot of Es too. Repeatedly, over many days, single hop Es when you would not expect it. Not the multi-country "Winter Es" we sometimes get for a day in December or early January, but regular weak Es to one of two stations at a time, over and over again. This could well simply be because there are more stations on FT8 looking for DX and I am hearing them. This out of season Es could have been there all along but was not noticed. I regularly say on this blog that Es can happen any time of year, but I did not have this regular stuff in mind. But here it is. I am not convinced that this is a new form of year-round Es, I think it is just us noticing it.

I feel this is a bit like something Sherlock Holmes might say, but when you have eliminated all the likely options, the unlikely option must be the answer. No, the figures are not high enough for 6m F2 to arrive, but it looks like it must be here. Who decided on those figures, and why are they in the books? The evidence is in my log, and Dear Doctor Watson can testify to that.

What would Sherlock Holmes do next? Probably retire to his fireside, get out his violin and reach for his magic little bottle of liquid refreshment. Such things are not for GM4FVM, probably a cup of tea and some fig rolls in the shack for me. I think my fig rolls do more for my thinking than Holmes's full syringe ever did. I need a clear head for this stuff. 

My first Winter proper 6m DX. At last. Not just a day working 1500km through Europe, but a week of activity far and wide.

I just wish it was not so cold.

View North at GM4FVM on 2 December 2023 (Photo Mrs FVM)

To all other VHF DX-ers my call is this - "Get on and work some while you can". 

The next sunspot maximum is a long way off, and this one is clearly here now.

73 Jim


Thursday 16 November 2023

Unusual 6m propagation this Autumn

I have not been very present on this blog lately. There has been a lot going on, plus I am having trouble posting replies to other postings. I hope I can get the posting problem resolved soon.

This is an update. There should be a series of links at the end to the various surprised posting I have made on this subject earlier. 

I used to work almost nothing on 50MHz during the periods of the years which excluded May, June, July and August. In other words, outside the Es season there was little to hear, even though of course I still listened. Based on 14 years experience, both at the top and bottom of a (weak) solar cycle, there might be a few days of European contacts to be had. Maybe a little aurora or meteor scatter, but nothing outside this continent.

For the sake of simplicity, henceforth let me call the period September to March "Winter".

There was no "DX" outside Europe to be worked on 50MHz during Winter. That was the rule for over a decade.

What could I do during Winter? I could look at DXMaps and the DX Cluster and for a month or so around October and March each year when I could see Australian stations working into Japan and the odd contact from South America into Southern Europe. This was Trans Equatorial Propagation (TEP) and these contacts had nothing to do with me as I was outside the area covered by TEP. Frustrating.

Back in March 2015 I wrote about "TEP, Something I don't get here" accompanied by a map showing that it did not reach much further north than the Alps.

Proof of the rule was that listening produced nothing. Absolutely no DX. The minimal Es was truly sporadic, weak, fleeting and within 1500km. Nothing to suggest that Es was anything other than a rare event during the Winter. Perhaps a day of European contacts, but you could not rely on it any particular day.

This blog is full of reports of brief 50MHz openings during the Winter, but all of them are linked to specific solar activity. None of them involved any "DX". DX in this case means outside Europe. I am happy to work around Europe during these rare events but they are not startling. None of them showed an Es opening every day for weeks on end, just the odd day. Actually, they were interesting because they were so unusual and short lived.

During the Winter I could also read Don Field G3XTT's book "Six and Four" which listed all sorts of long distance DX from solar cycles long since past and estimated that for there to be classical F2 openings we would need the solar flux level of over 200 for two or three days for an F2 opening on 6m. As I write the flux number is 134 and it has only been above 200 for a couple of days and not since January. Not much chance of long distance DX on 6m then.

And then it all changed.

For me the change happened on 20 October 2022. I worked TT8SN. Very unusual during Winter as this sort of thing had only happened here before during the four Es peak months. In fact any African contact was unusual even during the Es season and not that far!

Here is my DX (over 3000km) worked on 6m since the end of this year's Es season.

50MHz contacts at GM4FVM between 1 September and 14 November 2023

As usual, click to enlarge the images if you need to.

OK, it took over 72 days to do it, but 7 countries all over 4500km. Nae bad. Best DX 11869km. Only one of these countries was worked by me on 6m before this year, and that was Brazil which I only worked during the Summer. This was all new Winter DX. 

This was when the flux index appears to be too low for classic F2, and when Winter Es has never produced multi-hop for me. Ihave a station well short of the bruising mega-gear used by some. All I can say is .. wow!

Since the end of the 2023 Es season - Brazil, Chile, South Africa, Reunion, Botswana, Senegal, and Burkina Faso. During the equivalent period before the 2023 Es season - Three South African stations - a first for me then.

For now I am assuming that this is TEP which I can link into thanks to Es. And there has been Es. Unlike previous years there has been regular Es openings during which I have been hearing or working stations in Southern Europe almost every day.

Here is a typical day on 6m these days:-

50MHz on PSK Reporter at 14:35 on 14 November 2023

This certainly looks like TEP, and I must assume that Es is what is linking stations as far north as me into it.

This is happening on many days when I might have expected it to be confined to the usual TEP windows during October or March. Also, it has taken regular Es to allow me to reach it, and that is unusual too.

It has become so regular that I declined to try to work some stations as I had already worked them. I am turning down contacts at 10,000km because they are currently every day contacts. I can watch other GM stations working them. Once or twice I have got involved simply because I can.

I now often report long distance 6m contacts to Mike, GM3PPE and he has helpfully done the same for some of the contacts I have made. Two days ago I worked a ZS but did not notify Mike because such contacts have become almost an everyday event. A year ago I would have been thrilled with this, now it does not seem quite so surprising.

Surely this has to come to an end. The theory behind TEP suggests that it is limited to the equinox along the geomagnetic equator. That means it should move along the equator for a few weeks and not exist along a set path for a long period. But it is mid-November and it is still happening.

Perhaps it has now come to an end. Today there was no opening and I only observed one contact between Australia and Japan. Even that was probably the shortest possible path between those countries - Darwin to Okinawa. Against that idea is that the considerable opening shown above was just two days before I write this. On 14 October I worked ZS6NJ. On the Es front, on 15 October I worked 12 stations in 11 countries (not rare DX, except possibly GI4DOH). Hardly signs that this is over.

Why is it not over when the books say it should have ended weeks ago? I have no idea. Why is it happening in the first place when it never happened here before 20 October last year? I have no idea about that either. 

In his book Six and Four Don Field distinguishes TEP from "East-West F2" propagation. There has been no East-West F2. This can hardly be classic F2 due to the paths. If it was East-West F2 then where are the stations due East or West?

So it cannot be F2, it cannot be just TEP alone as it needs Es at the same time. If TEP and Es are involved why are they both around regularly in Winter when they never were before?

If you live on the South Coast of England or further south you may be wondering what all the fuss is about. Well, you may be able to work TEP every year, though not normally for such a long period. Up here in IO85, for GM4FVM this coincidence of Es and TEP (if that is what it is) is totally without precedence.

Links to earlier posts:- 

March 2015

"TEP, something I don't get here"

October 2023

"Senegal on 6m"

September 2023

"Long Term milestone reached"

February 2023

"More TEP from Scotland?"

January 2023

"TEP from Scotland Mystery"

Finally - I do not really understand this propagation. At one level I don't care. I am happy to work the DX.

73 Jim


Monday 16 October 2023

No F2 propagation on 6m? There is on 8m

Someone asked me "what difference does it make whether something is TEP or F-layer propagation?"

Many of us have been hoping that there might be F-2 propagation on 6m so that we could work some juicy DX. All I have seen so far this solar cycle is TEP. TEP is nice, with long paths, and even some from the northern hemisphere (see last posting). I have seen no F2 propagation on 50MHz yet, and anything I have seen is almost certainly TEP or related stuff.

I have seen contacts reported to the cluster claiming to be classic F-2 propagation, but on closer inspection these look like TEP or related methods. I am not the police force, nor a judge deciding which is which. I just try to decide so that I can make the most of the situation.

I have not seen classic F2 on 6m so I need to go down a band to illustrate what I mean. I have thought of showing a map of 10m but that is too crowded. So here is a screenshot of PSK Reporter on the "40MHz band".

40MHz signals shown on PSK Reporter 14 October 2023

You can see the TEP heading south from Europe to Africa. I recorded 15 different callsigns here that afternoon. We see that north-south type of propagation on 6m from time to time.

Then you can see the trans Atlantic paths heading West. I have not seen anything like that on 6m yet. There was a long, strong, F2 opening on 40MHz on 14 October between Canada and Europe.

So the difference is that TEP paths cross the equator around the equinox, or they are "F2 Single-Track" which from here heads towards the equator but does not cross it. On the other hand classic F2 is much more directly related to the sunspot cycle and you can sure it is that method if the path does not pass anywhere near the equator.

Now there may be classic F2 paths which cross the equator too and if we get widespread F2 openings I will be happy to see them. None here yet. TEP is very distinctive and although it is influenced by the solar cycle we have been seeing it around the equinox for years.

What difference does this make if something is one propagation mode rather than another? Well you could say no difference. Many amateurs just work what they hear. But for me who likes to seek out DX then I can hunt out TEP paths at certain times of the year more or less every year, whereas classic F2 is a solar maximum event on 50MHz. One clue is that if they come from totally different directions you can have a good idea which is which.

The map above seems to show that F2 paths have crossed the Atlantic at 40MHz. You have to be a bit careful with PSK Reporter or cluster paths because many are misreported. However in this case I am pretty confident that these reports are genuine.

It is easy to look at PSK Reporter or DX Maps and see long DX paths which may look like classic F2. Lately there have been many of these on 6m which are near and across the equator. The maps show the paths as great circle lines spreading far north and even north of Scotland. There is no point me hoping to get in on these openings. I reckon that these paths are TEP-related and do not come this far north at all. Nothing like that has come my way yet on 50MHz, and I am not expecting it from that type of propagation. From what I have seen, up here we have just had rare shots at TEP by Es linking.  

So there have now been signs that classic F2 has reached 40MHz. This has been widely reported. Will it reach 50MHz? I do not know. We shall see. Meanwhile, I am still looking for TEP.

I have to say that the evidence from 40MHz is very promising so I might get F2 to work on 50MHz very soon. Or maybe not.

Does it make any difference to know that what I am seeing at 6m is not classic F2? In my case, I think this knowledge helps me to point my antenna in the right direction at the right time. If you know what to expect you can be prepared. I am hoping for more TEP, and there is a chance some day for classic F2.

Some day. Maybe.

If I knew what was going to happen then 6m would be like 20m. I could not cope with that.

73 Jim


Friday 6 October 2023

Senegal on 6m. Not trans equatorial, but still TEP?

 I have been away again. This time to Poitiers in France

GM4FVM in the cafe in the Blossac gardens in Poitiers France (photo Mrs FVM).

This photo does look a bit like one earlier this year in Vught in the Netherlands, though with a different Belgian tipple. Anyway, no radio on this trip. I note that once again, on my second visit to Montparnasse station in Paris, I was stopped and asked for a ticket by an RATP official. I am not sure if it is because of the way I look. Maybe they had intelligence that I might be a ticket dodger. Still, I suppose two visits separated by 35 years is a small sample. I must watch out for this again, as the Metro journey from Gare du Nord to Montparnasse is never easy at the best of times.

What follows has been revised on 12 October 2023 to include updated diagrams. It has been developed into a fuller article and this should appear on this blog later.

Back in Scotland now, on 28 September I worked Elivra, 6W/IV3FSG, in Senegal on 6m.

50MHz contacts at GM4FVM on 28 September 2023

As usual, click the image to enlarge if necessary.

This contact reminds me of the one with TT8SN in Chad on 20 October 2022. This distances are similar - TT8SN is 5084km, while 6W/IV3FSG is 4766. Both are at the southern extreme on the Sahara desert. Both were happening at around the time of Trans Equatorial Propagation (TEP) further south into Africa. That posting can be found here.

At the time I pointed out that the propagation mode behind this contact to Chad was a mystery. Now after another one I feel a bit more certain as to how it happens.

In this recent case just before I worked 6W/IV3FSG I worked EA2AR and F5TMJ (LA3EQ had been worked 10 hours earlier). So there was Sporadic E towards the south of me. Later I heard V51WW in Namibia which was clearly TEP as he is on the other side of the Equator. I heard GM6NX working ZS6NK, so that is further evidence of crossing the Equator by TEP. Also, I could hear Spanish stations working V51JH and V51CO in Namibia. I was also hearing station in the same area when I worked TT8SN last year.

So that seems to sew it all up. There was Es from here to Spain, there was TEP from Spain across the equator to Africa, and presumably Es linking to TEP from Scotland to Africa. Es linking to TEP. Problem solved. That must be how I worked Senegal.

Erm... there is a flaw in this logic. Senegal is not across the Equator from Scotland. It is 14 degrees north of the Equator. Ah but, you say, that is the Geographic Equator. For this purpose we have to consider the Geomagnetic Equator, which is diverted north across Africa. True, but the diversion is not enough to put the Geomag Equator north of Senegal. From what I can see it passes just south of Senegal.

One of the many representations of the Geomag Equator on the internet

None of these images on the internet are too clear. But I conclude that the Geomag Equator passes just south of Senegal, maybe about 12 degrees north of the Geographic Equator.

So if the signal from 6W/IV3FSG was an example of  TEP propagation, it did not cross either of the Equators. There seems to be something in the expression "Trans Equatorial" which suggests to me a crossing of the Equator.

OK, having read various articles, especially those written by James Kennedy K6MIO/KH6, I think I have now got some sort of a grasp of this. Based on his ideas I have created a diagram showing the process.

Generalised representation of classic TEP (after K6MIO/KH6)

This shows the "classic" impression of TEP. Ionisation well up along the Geomag Equator and rises up into the F-layer, forming two "anomalies" or "electron pools" as K6MIO/KH6 describes them. The signal path rises from one side of the Equator, gets deflected twice at the anomalies, and reaches the receiving station on the other side of the Equator (and then presumably extending by Es to reach me). Great for V51WW in Namibia, but not so good at explaining hearing 6W/IV3FSG from Senegal.

However, K6MIO/KH6 does have an explanation of observed propagation effects which does explain both stations being on the same side of the Equator. In this case, I reckon "Trans Equatorial" refers to the effect in the ionosphere as shown by VK4YEH. This type of TEP is decidedly one sided.

K6MIO/KH6 describes the one sided effect as "Single-Lane F2" propagation. In his articles he shows diagrams of many TEP paths which are entirely in the north "Lane" reaching only north of the Geomag Equator. The paths he shows are mostly across the Pacific and several run generally south east to north west, but he also shows one running north east to south west . However, in the text he suggests that they can run north-south. The path to Senegal from me runs north east to south west at azimuth of 201 degrees.

James also says that the two stations must be within about 2000km of the same ionisation peak and if north-south they must be on opposite sides of the lane. Now I have done a little back of the envelope investigation of these figures in relation to my QSO. If indeed Senegal is close to the Geomag Equator (which the internet maps suggests it is) then it is far on the opposite side of the lane from Europe. James' article suggests that the skip points will be between 10 and 20 degrees from the Geomag Equator.

OK, assuming that TEP got the signal to Spain and Es carried it the rest of the way, my calculations suggest that the Senegal-Spain section would be about 3000km and the Spain-Scotland section would be about 1700km. These are both well within the potential of the two propagation modes. All the other conditions in the K6MIO/KH6 paper seems to be met. This looks like "Single-Lane F2" as described in the TEP articles.

K6MIO/KH6 has done proper scientific research and analysis, I have just read his articles. I am no earth scientist. I have used his ideas as the basis for a diagram which I think represents the situation on 28 September when I worked Elvira in Senegal.

50MHz situation on 28 September 2023

I come to the conclusion that Single-Lane F2 is the method of propagation behind both of these contacts - partly by being convinced by K6MIO/KH6's scientific rigour - and partly by ruling out the alternative explanations.

Multi-hop Es looks very unlikely. I hate to write "never", but I cannot think of me ever seeing multi-hop Es at this time of year. Sure, there is Es all year, but outside the peak season (in my experience) it is single hop only. It would need to be three hops for this contact, two would not be enough. Add to that the time which was 19:30 local, and then multi-hop Es at this time of year seems extremely explanation. In July, maybe, but not in late September. Unless of course there is new type of multi-hop Es ....

Ordinary F-layer? I am pretty sure that the southern African stations were TEP and not F-layer propagation. There are  a few signs of what might have been classic F-layer propagation but not enough to convince me that it has happened yet. Of course, TEP is F-layer propagation, but a very different type.

No, given that there was classic TEP and single-hop Es at the same time as this QSO this definitely looks like Es linking to "non-Trans-Equatorial-TEP" or to give it a better name "Single-Lane F2 associated with TEP".

I could say a lot more about Es linking and the distances involved in single-lane TEP, but I will not do it here. Let me just leave this as an idea. The idea is that when there is classic TEP around linking me in Scotland with the far south of Africa, there also seems to be [something] linking me with much further north in Africa. These shorter paths do not cross the equators. I believe that the [something] is single-lane TEP. In believing this I have thought about classic F-layer and multi-hop sporadic E propagation and rejected both as likely candidates.

OK, maybe [something] is another entirely new propagation method which just happens to occur when I hear other TEP. I doubt it.

Just because the path of a contact does not cross the equator does not mean we can rule out that it is caused by a trans-equatorial effect, such as TEP. 

I see this type of propagation posted as TEP. The correct name in the articles is "Single-Lane F2" but as it is associated with TEP I doubt if anybody is going to change their idea of what to call it. So I will continue to post it as TEP for now as it is not classic F2 propagation either. Put another way, I do not believe that these contacts would have happened but for the TEP event which was noted at the same time. 

Bit of a description dilemma there for now.

73 Jim


Wednesday 27 September 2023

A classic case of Television Interference

Anything which transmits radio frequency signals seems to have the potential to create television interference (TVI). Well, pretty much anything that I can think of, if it is positioned in the wrong place.

There are plenty of things to consider when looking into these cases. Why has the interference started? What has changed? If you can answer those questions you stand a chance of solving the problem.

Fundamentally of course the television has to be capable of dealing with RF signals on frequencies other than the ones it is intended to receive. The manufacturers claim that this is true. These days they are generally pretty good at this, but you cannot rule out this as the root of the problem. And then, even if the TV is OK in this respect, possibly some wideband distribution amplifier is not good a keeping out signals from outside the TV band. I would suggest, look for a wideband distribution amplifier as your first possible culprit.

So, when I got a report of TVI coming from a neighbour I immediately wondered what had changed. Oddly, nothing significant had changed on my side for a few years. True, I had got stuck when my knee failed at a time when I was in the middle of moving antennas about. Now though all those antennas are back where they had always been. Even my 28MHz vertical, which I use on 24MHz as well, is back where it had been several years ago.

If my antennas had not changed, and the neighbour said that her TV setup had not changed for a couple of years, then I was a bit stumped.

This seemed like an odd one, but in the end the same thing solved it as usually solves such things - a braid breaker.

Garex HPF1 HPF and braid breaker similar to the one used

I first used a braid breaker for this purpose within weeks of first being licensed all those years ago. I think I still have that one somewhere ...

Anyway, at first it did not seem too obvious what was wrong and it was too soon to jump to conclusions.

As usual, the neighbour had come to me with certainty about the interference, but no definite dates or times. This is not her fault as it is not her duty to keep a logbook. She had contacted her TV antenna installer who thought it might be due to telephone interference. This type of interference came about when part of the "Freeview" terrestrial TV frequency allocation was given over to mobile phone usage. That sounded a bit unlikely to me.

I had in my mind an incident which happened a couple of years earlier. The same neighbour had come to me as she had knocked the preset channels off the television in her bedroom. She asked me to retune the channels. This proved to be very difficult. When I checked it the signal level at the antenna socket in the bedroom was at a very low level, to the point that tarnishing of the socket was preventing any useful signal reaching the TV. By cleaning the plugs and sockets I managed to get the thing tuned, but it was marginal. At the time I suggested to the neighbour that she call her antenna installer and get him to check out why the signal was so weak.

From this visit I had gained the impression that there were three televisions in the house (bedroom, kitchen and lounge), which implied that there would be a distribution amplifier somewhere. The antenna was probably in the attic space, a common arrangement around here. The main TV was connected to a "BT box", which is an internet connected entertainment console, plus a DVD player. There were plenty of coax and internet leads around to pick up rogue signals, though over the years I have added ferrites anywhere I could, as much to keep them from radiating noise than picking it up.

TV in this area is served by an infill repeater on the nearby headland overlooking Eyemouth. The field strength from the repeater is high, but this repeater offers very few programme options. Several villagers have erected tall masts to point at the main transmitter (Selkirk). Although we are outside the Selkirk service area they still get a reasonable signal, though when I tried this some years ago it could drop out at times. Faced with this problem, most of the other villagers have installed "Freesat" satellite TV, or have subscriptions to Sky TV. We have Freesat.

Unusually, this neighbour uses the local Freeview UHF repeater, which is within sight of her antenna. It seemed odd to me back then that some time ago she was getting such a weak signal on her TVs, and indeed, was only now getting TVI.

I sought advice from Mike, GM3PPE, who kindly offered to help. It is impossible for one amateur to use their equipment and monitor TVI at the same time. Mike also agreed to come over and do some tests. We pondered over what could be happening as we went round with various pieces of test equipment, a jar full of ferrites, and a box of braid breakers. The main TV was getting a strong signal now (something had changed but at first I did not know what). We checked things out and went up to look at the antenna. In the attic space we found a mains powered distribution amplifier with four outputs. The LED light on this was on, but beside it was another Labgear amplifier, also with four outputs, which was disconnected.

TV distribution preamp similar to the one involved

Now we started the tests. I left Mike with a PMR hand portable and I took a second handie back into the shack. I then transmitted on all the frequencies I normally use, beaming in various directions and using different power levels. Mike watched the television in the lounge which had been affected by TV and reported back.

As soon as the tests started the surprises began. Having found the distribution amplifier I had guessed (correctly as it turned out) that the amp was being affected by my signals and not the television directly. I was wrong however in assuming that it was suffering from overload. I had feared that the electromagnetic field I was creating was simply overwhelming the amplifier circuit boards, as sometimes happens. Not in this case.

Mike quickly reported that I was indeed causing TVI on some bands (4m and 2m, which surprised me), but lowering the output power by 3dB stopped it entirely. Likewise, moving the beam antennas 10 degrees or so away from the TV antenna also stopped the interference. Rather than totally swamping the amp this looked like there were simply unwanted frequencies getting into it and being amplified, probably arriving down the antenna coax. 

With swamping, where the signal is getting directly onto the boards, quite small signals can cause big problems by desensitising the amplifier, and there tends to be a "cliff edge" effect whereby only by reducing the signal to a very low point does the interference stop. I was still thinking about the time in the past when I found low signal levels, and I thought any desensitisation would cause problems. Here, though, the interference weakened very quickly, and seemed to be stopped entirely at about -3dB lower signal at my end. This should be fixed fairly easily, I thought.

Next stage was to try a filter in the antenna lead between the antenna and the amplifier. I had various devices in my box, including 50, 70 and 432MHz notch filers, and several general purpose braid breakers. At this stage Mike's wise approach came into play. He studied the data sheets for the various braid breakers to check which would introduce the minimum attenuation to the wanted TV signal. My approach was a bit gung-ho, so I would have just tried something. Mike rightly wanted to select the best one for the purpose. The best one of the bunch turned out to claim an insertion loss of better than 2dB "at UHF". Other details were rejection on the inner of better than 60dB at 30MHz and below, and better than 25dB at 30MHz and below on the outer. Given that 3dB seemed likely to do the trick we tried this. 

The choice was made on the basis that although the HPF1 filter I brought had greater rejection of the unwanted signal, it did not quote a insertion loss, whereas the HPFS had a quoted figure for loss at TV frequencies. Based on the tests we felt that we did not need more rejection of lower frequencies. Of course, I use frequencies up to 432MHz (I doubt if 1296 is an issue) so the attenuation will be less as the frequency rises, but it seemed like a useful first step before trying the notch filters. In the end we did not need to try anything else.

I fitted the braid breaker (the HPFS, not the similar HPF1 in the photo above) and returned to the shack to do the tests again. Mike reported no TVI. Not on any band, at any power, beaming in any direction. Mike then moved on to the television on the bedroom and achieved a similar result. So what had happened to suddenly cause this TVI?

The homeowner told us that the antenna installer had installed the current distribution amplifier a couple of years ago. The old one, which I guess had failed and was the cause of the weak signals I had noted back then, was a neat Labgear. Like most Labgear amps, no doubt it was well screened. The new one produced a stronger signal for her but was wide open to interference. So why did this not prove to be a problem immediately when the amp was replaced? Well, probably because this was when I had my antennas moved while I was recovering from my knee operation. At that time they were displaced, but lately I have put them all back where they had been originally.

When the TVI was reported I could not work out why, when everything was where it always had been, there was suddenly a problem. But the new preamp had been there for a while and it could not have coped with my original layout as the old preamp could.

Incidentally, we never did see the TV antenna involved. Once we found the preamp there was no need to climb any further. We simply connected the braid breaker into the input of the amplifier. Checking the antenna would have involved a lot of attic crawling which was not needed. Clearly there was enough signal getting down the coax, wherever it was coming from.

Also, there turned out to be a fourth output from the preamp, feeding a TV in another bedroom. We just did not know what we were going to find that day. As it turned out, there was a proper preamp, and it worked quite well once it had a filter added to the input. I attached a label to the filter "Do not remove" - we can but hope.

Initially I had feared that, as in some other houses, we would find a non-amplified "aerial splitter". These "dumb" splitters introduce 3dB loss per output. Some antenna installers fit them to avoid installing mains wiring and possibly later to rule out the possibility of preamp circuit failures. It is true that the earlier preamp had failed, so perhaps the point is arguable, but for me a properly installed preamp should always produce the best results.

So that seems to be that. It is impossible to check every outcome at different power levels and beam directions but several weeks have now passed and no further complaints have been received. I have checked and the neighbour seems quite happy with things as they are now.

I could not have solved this problem without the help of GM3PPE. His advice was very valuable, and he carried out the tests at the other end. He tactfully discussed the issue with the neighbour and provided a very useful expert for her to rely on. Thanks Mike.

Now, what is next?

73 Jim