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

GM4FVM

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

GM4FVM

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

GM4FVM

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

GM4FVM

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

GM4FVM

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

GM4FVM

A tropo opening at last.

Perhaps the strangest thing about this latest tropo opening is that it is so long since the last one. My most recent posting here on this subject was in early June, 3 months ago.

I think of Summer in this part of the UK as not being particularly hot but often having long settled sunny spells associated with high atmospheric pressure which brings tropospheric enhancement. Not this Summer. After a promising start, July and August were grey and miserable with low pressure for weeks on end. Of course the low pressure does not last for ever, just like the high pressure never did.

During the period 4 to 9 September a series of high pressures passed from West to East. For a time there was a low pressure system to the North West of me (as there often is) which brought winds and shut down the propagation, but generally conditions remained up for most of that period.

Things seemed to be best on 144MHz, with 432 not bad and 1296 pretty poor.

144MHz contacts at GM4FVM 4to 9 September 2023

39 QSOs into 30 different squares was a very agreeable outcome.

Those of you who have clicked on the image to give a better view of the map may have noticed that F6ASP appears to have his station located in the middle of the English Channel. If that was true the UK Border Agency would be out to try to send him back to France. In fact what has happened here is that because I only have a four character locator for that station the map assumes that he is in the middle of the JO00 square. This happens a lot, and I have to look up six character locators for some stations who do not list them on QRZ.com, or for which VQlog does not have the full details. In this case F6ASP does not have a more precise locator anywhere that I can find it, so he will have to remain in a watery position for now. 

Queue the tune "Sailing By" written by Ronald Binge, which is played by the BBC before the Shipping Forecast. This is now used by anyone too lazy to find anything more relevant to the sea. I am as lazy as the next man. I know Claude Debussy's La Mer and Benjamin Britten's Sea Interludes might be better but perhaps I will just stick to what I always do. This "don't blame the lazy" theme will return at the end of this posting, but by then it might have some amateur radio relevance [about time Jim, this is not a music blog].

On 5 September I had the chance to operate for a short period during the NAC contest. I switched to using the EU contest mode in WSJT-X and worked SM7VUK, DG1BHA, SB7A, SK7OL and SM7SPG in 33 minutes. I could have worked more but had to go to attend to domestic duties. Contests have their uses but I am not about to become a slave to them.

Things seemed to be going pretty well on 5 September so I decided to try coming on to 2m at 05:00 local time on 6 September. This was to see if the supposed good conditions early in the day would pan out. I was pretty pleased then to work EU3AI in KO22, a distance of 1757km, at 05:40 UTC. Of course I have worked him before (!), but this time it was tropo which is definitely the hardest way to work Belarus. 

Having worked Belarus on 2m both of the easy ways, by meteor scatter and Sporadic E, doing it on tropo seemed to complete the set somehow. Just as people say that if the Jumbo Visma cycling team win the Vuelta a España this week, resulting in a clean sweep of winning all three Grand tours this year, somehow doing it three times in different circumstances makes them invincible. It doesn't mean that of course, and nor does me working Belarus three different ways mean anything very significant other than that I was in the right place three times over.

Still, I am claiming that my early arrival on the band that morning was the result of superior planning on my part and shows how knowledgeable, dedicated and devoted I am to my hobby. It doesn't mean that of course. Ever heard on insomnia? What else do you do at that time of the morning other than listen to the radio?

I also heard two Russian stations in the Saint Petersburg region and one Ukrainian station, but did not work any of those. I cannot complain though as 15 countries worked on 2m is five days is still pretty good.

OH1ND in KP00 is 1493km, still a good trip on 2m, and LY2WR in KO24 is 1681km, barely 70km short of EU3AI. So there was plenty of action short of the ODX.

Moving on to 70cm

432MHz contacts at GM4FVM 4 to 9 September 2023

35 QSOs on 70cm is only four less than the 2m total and shows how well we can do on that band during reasonable lift in conditions. SM0DJW in JO88 is a pretty good contact on this band at 1242km. There were more contacts into PA on 70cm and there is no doubt that the path from me into Benelux on 70cm can often be better than 2m. Once again the DXCC total is pretty good - nine countries worked on 70cm would have been a good lifetime haul for me when I started out on this band. 

Meanwhile on 23cm...

1296MHz contacts at GM4FVM 4 to 9 September 2023

On the face of it, 23cm looks like a bit of a washout compared with the other bands. It did not feel like that at all. The QSO with  G4YTL was particularly interesting. We were in contact via KST chat and after setting up the initial details, it took 20 transmissions from me on FT8 for David to decode the two that he needed to complete the contact. That is over a distance of just 427km during elevated conditions. We then switched to Q65 and competed a second QSO in just over a minute. In FT8 David could not decode 18 of my 20 transmissions, while on Q65 he decoded all of them (just three needed to complete).

There is nothing very starling about this. I have worked David on Q65 on 23cm before. What surprised me was seeing the comparison in modes play out. Q65 is simply a superior mode to FT8. The difference may not matter much on HF or during favourable conditions on other bands. However, once we reach marginal conditions or bring into play scatter propagation as with aircraft scatter or EME, then Q65 shows how good it always has been.

This brings me back to the question I often ask myself. Why, when Q65 is better, do VHF and above operators still not use it? It seems to me to be absurd that many EME operators on 2m still use JT65. If we could bring Q65 to bear during ionoscatter or troposcatter it might well make the difference between completing a contact and failing totally.

Sure, if you are on a chat room like KST (argh, how I dislike that but needs must) you can set up a Q65 contact. But what about the generality of contacts which happen randomly? Could VHF operators not decide as a group to use Q65 instead of FT8? This is a bit like asking why some people still use FSK441 or RTTY. They use outdated protocols because they do not want to change. They have every right to use old modes, and I do not deny them that right. But that is like saying that they have the right to miss all the QSOs. Sure they do. Knock yourself out with that idea, mate.

In conclusion ... this opening was a test for me to check out the two band with two feeds DUAL 2m/70cm antenna. I doubt that it can be quite as good as the I0JXX for 2m and the Wimo for 70cm because they are single band antennas and are designed for that one job. However, it went pretty well and I think I should be content enough about that.

Now, the 23cm antenna might now come into the reckoning for change in some way. Elevation? Time to think again about 23cm EME?

73

Jim GM4FVM

A long term milestone reached at last - and TEP or multi-hop Es in September?

It is sixteen years now since GM4FVM returned to Scotland and took up this callsign again. After a busy few years of moving from GM to GI to G, finally we came back to Scotland. Finally (I think). Mind you, having done G to GI to GM before that, you never know.

It took a while to get established here, and I had my first 50MHz contact as GM4FVM on 23 February 2010, over thirteen years ago. That was to GM8BDX in Birgham, less than 30km away, but it produced DXCC number one on 50MHz. 

So that was the start. It was three months before S53CC gave me DXCC number two.

By March 2017 (only seven years later!) I had reached 55 DXCC on 6m, over half way towards that magical DXCC itself. DXCC on one band still seemed a bit of a stretch for me. However, by March 2018 the total was 63 and by the end of 2018 it had reached 71.

I think you can see where this is going.

By July this year the total had reached 93, and a month ago 99. Almost there. However, that seemed to be it for 6m Es in 2023. This year's Es season appeared to be over and certainly as far as multi-hop Es was concerned.

However I still keep an eye on the space weather via Solarham (link in the sidebar). There was a disturbance on 3 September. The data on DXMaps.com stated "SWX=Moderate Storm" which was enough to get me interested.

I had been checking in at the shack at various times just in case something happened. Otherwise I was watching an excellent episode of that reliable Kiwi detective drama "Brokenwood Mysteries". This one surrounded a murder amongst a female motorcycle gang and I got quite involved in the plot. I do think that the arrival on the scene of Detective Chalmers has definitely brought a slightly more gritty angle to this series - and it needed it. Anyway, I devoured the whole thing.

When I strolled into the shack again at 20:59 UTC I was surprised to see that there was a lot of traffic on 6m from the direction of South America. In fact, I saw Gordon GI6ATZ working a CE station and David GI4SNA working an LU7. Time for action.

By 21:06 I had worked PU4JOE, and then CE3VRT by 21:09. And that was it. CE3VRT was my first 50MHz contact into CE from here, and also CE was my 100th DXCC worked on the band. Job done.

Contacting PY5EW completed activities for the night, at 21:13.

50MHz contacts recorded on DXMaps on 3 September 2023.

DX Maps tells the tale but maybe does not answer all the questions. All of those contacts into South America are shown as Trans Equatorial Propagation (TEP). Yet, when similar contacts were made a week or so earlier they were all recorded at Multi-hop Es. There certainly was Es about as can be seen by the red lines within Europe.

Was this TEP at 21:13 in September, or multi-hop Es, or a combination of the two? I do not know.

Moving on from that question, I had to check Clublog just to see that they had acknowledged my 100 score. You never know you know, someone near to me might have sabotaged me sending Clublog the details. You do not need to be paranoid to write this blog but it makes it a lot easier to fit in if you are.

Clublog personal DXCC chart page for GM4FVM

Well, I can move on from that too. 

The achievement moves me to 1523rd place in the Clublog 6m DXCC list. I would not describe that as having achieved greatness. I am 1523 steps down the ladder from the top, but rising to the top has never been my ambition. I only do this to measure how my station is operating.

Who cares about places on that DXCC list? Not me.

These little milestones just serve to motivate us and to check if things are getting better. They might spur us on to improve the antenna or something similar. After that the next thing happens.

I am more interested in the mode of propagation which got my 50MHz signal to CE3VRT than the achievement of working 100 countries. Even more intriguing was reading CE3VRT's QRZ page about his efforts at 23cm moonbounce using a 1.8m dish.

Hmmm. Most interesting.

73 Jim 

GM4FVM

Italy returns to 70MHz, and data mode confusion breaks out

Italian stations were granted access to the 70MHz band again from 6 August until the end of 2023.

Here is the information for the many of you who read this blog who are fluent in Italian.

Italian 4m authorisation 2023.

OK, given that we are reaching the end of the 2023 Es season the timing could prove to be a bit unfortunate, but we might be thankful for what we have got.

Once again the authorisation is for spot frequencies and a band 25kHz around those centre points. As before the spot frequencies are 70.100, 70.200, 70.300 and new for this season is 70.400 - for FM I guess which was on 70.300 under previous allocations. Power is 10W and all normal modes and directional antennas are permitted.

It is a good 10 years since Italian stations could use 4m and a lot has changed in the meantime. For a start, many stations have equipment ready which can operate directly at those frequencies. Also, several more DXCC "entities" have appeared on 70MHz over the years which are new countries for Italians. 

So, as you might expect, there was an avalanche of stations from Italy seeking to work everyone around, including me. On 12 August I worked 20 Italian stations on 4m. Any why not? New bands, new DXCC, new squares, new "slots", all good stuff for the Italian stations. Only one new square for me though. I have seven or eight squares to get in Italy, plus a few more watery ones which look tricky. Mostly I need to work stations in squares in Apulia, Calabria, Campania, and Molise. Northern Sardinia and Eastern Sicily remain to be worked, as does one surprising square in Liguria and Piedmont right up on the French border. 

The reason why I have not worked these squares is no doubt simple. These are areas of lower population density, though the missing one in Sicily is a bit odd. Still, plenty of work to do there Jim.

I presume based on earlier authorities that San Marino, Vatican City and the Sovereign Military Order of Malta will also follow suit. Once again the timing is not great as there have recently been activations from all three of these DXCC and I worked them all on 6m. So far I have worked none of them on 4m. Ah well...

So what do I mean about confusion? Well, in those ten years of no activity from Italy, FT8 and MKS144 have appeared on 4m. As soon as 6 August came Italian stations and those wishing to work them had to decide on a common frequency. The usual ones, decided upon by German amateurs when they came on the band permanently, were 70.154 and 70.174. Neither of the existing frequencies fall within the Italian allocations, so they used 70.190 for FT8 and 70.210 for MSK144. Fair enough.

Nobody publicised the change of frequency required to work Italians, or not where I could have seen it. I just used common sense, looked at PSK reporter, and changed to 70.190. Since 6 August all my FT8 QSOs on 4m have been on 70.190. Once again, why not? Well, both frequencies are bit close to the SSB centre of activity which is on 70.200, but we can manage that with a bit of give and take. When a UK contest appeared some SSB stations stuck to "their" contest frequency. The UK regulator, Ofcom, says we are "frequency agile". We can move, and that applies equally to data mode users. We do not own the frequencies we happen to regard at some stage as fixed points.

As things stand today, 26 August, a majority of FT8 operators seem to have moved to 70.190. A sizeable number are still on 70.154. I often see UK stations calling CQ on 70.154 and working nobody, while there are many stations in various countries to be heard on 70.190.

If anyone does not want to work Italians they can stick on 70.154, but that frequency is now falling into disuse. 70.154 is also not good for Portuguese stations. Myself, I can listen on both. My preference is for 70.190, at least for as long as Italians are to be found there. I have worked about a dozen countries now on 70.190 so a lot of other operators take the same view.

What frequency you use is up to you folks, so long as it is legal.

Over the past 45 years plus since I started on 4m, the frequency allocation in the UK changed, and  various countries have slotted in slices and spot frequencies all over the band (and slightly outside it). Radio amateurs are ingenious people and we have got over all these things in the past. This is just another one.

I have a big knob on my radio marked VFO. I can change frequency, and I will if that makes sense and does not ruin everything for everybody else. Nothing stays the same for long in my world, and I would not try to keep them the same anyway.

73 

Jim GM4FVM

Progress of a 6m opening to Japan and South Korea

I have referred to this 50MHz opening from Scotland to Japan and South Korea on 23 July 2023
before. You can find it mentioned here.

Since then I have tried to follow the progress of the opening on a map. Here is the list of contacts on the map listed by time of working ...

50MHz stations worked at GM4FVM on 23 July 2023

You will probably need to click on this image to enlarge it to see the detail.

With two outlying contacts, the opening started on Hokkaido at 06:51 and then moved progressively down the East Coast of Japan until 07:52. At that stage I became interested in working South Korea and spent a bit of time trying to work three stations there. Between 08:03 and 08:22 I worked 3 stations in South Korea and three more in Japan, after which the opening faded out. 

There was a fairly steady progression down the East Coast of Japan and only real outliers were two contacts back in Hokkaido at 07:58 and 08:01, which I have marked with grey hatching. There may have been gaps when the propagation did not make landfall and the band was open to areas of sea.

Of course once a station has worked me, they are not likely to work me again. You tend to see the front of the propagation moving, while the band is still open for a while behind the front but those stations have already worked me. I think that the reversion to those two stations in Hokkaido does not necessarily mean that there was a new opening, but rather a couple of new stations have come on the band.

We have seen this type of thing before during single hop openings, for instance as reported here in 2019. The pattern of Es contacts moving in a (more or less) steady line over time seems well established. But it was interesting to see it happen at the end of a multi-hop path as far as into Japan. Is this multi-hop Es? Certainly it looks like Es at the far end. I suspect that a similar analysis viewed from Japan would have seen the propagation open in a path across Europe or the UK.

What we do not know is how the signal gets between Es at my end and Es at the far end, I am having doubts about whether the "bit in between" can really be multi-hop Es. If Es moves the way we can see in single hops or at the end of a long path, then similar moves along the path to Japan would knock the whole thing off after a matter of minutes. If there were several hops all inclined to move along as we know Es does, then the geometry would mean that the overall path would be lost very quickly.

I do not have anything to suggest for mechanism working in the "bit in between". A special type of polar propagation has been suggested and who am I to disagree? It would have to be pretty stable to work for  75 minutes over a path several thousand kilometres long.

Anyway, it was interesting to see the same pattern of contacts moving across the region but this time at the end of an extended path stretching as far as Japan and South Korea.

73 

Jim GM4FVM

Be thankful for what you got

Can it be almost 50 years since I was first licensed? I sat my Radio Amateur Examination in 1974.

Ah, 1974. Simpler times. My revision notes consisted of one book someone gave me when I bought a receiver. And that was before they invented propagation, so no need to learn about that. But more on the days before propagation in a later post. Perhaps.

1974 had a warm Summer and "Be Thankful For What You Got" by William DeVaughn. What a great record for a hot Summer. Long and slow, with an insistent bass line and tight percussion. They don't make them like that any more.

"Keepin' up with Mr Jones? You don't need a loan!"

Despite William's advice I was later to borrow the money to buy an FT-101. Not exactly keeping up with Mr Jones, I told myself, just trying to hear and be heard.

Deary me. I still just want to hear and be heard. Yet, I get flustered when my station does not seem to be performing. I seem to have forgotten Billy's mantra about not to pushing on. I should be more thankful for what I have.

I also get frustrated about propagation which seems to have become "a thing" in the intervening five decades.

And so I was complaining about 6m propagation on this blog as recently as 9 days ago here

"That gap into North America looks very glaring"

but I also said 

"I have in the past worked in that direction into mid-August. There is still a chance."

Does complaining work?

Next day there was an opening and I worked 18 stations in the US and Canada over the space of 50 minutes starting at 13:09. I then had to wait four days until the next opening at 12:10 when in 26 minutes I worked 22 stations across the Atlantic. And two days after that I found the band open at 21:07 when I worked 9 stations in 23 minutes, and the activity only stopped when I realised that I was falling asleep.

US and Canadian stations worked on 50MHz at GM4FVM from 24 to 30 July 2023.

Total opening time was 99 minutes for 49 stations, which on FT8 means being pretty busy. All three openings met my standard for a pile-up, in other words I was not calling CQ but people were calling me and a queue formed to work me.

Perhaps I should complain less and be thankful for what I have got.

I heard somewhere that patience is a virtue. Maybe I should become more virtuous. 

Not so sure about that one. 

"Be Thankful For What You Got" sleeve. Image: Wikemedia Commons

73 

Jim GM4FVM

Honey, I blew up the linear amplifier

Well, the linear amplifier blew up, but it seems it was not necessarily my fault. Nor was it the fault of the linear.

This took months to resolve so this is a long posting.

Of course, I have a long history of blowing up linear amplifiers, going back almost 50 years. I trust linears less than any piece of equipment I have. They are almost always about to let me down. Having said that, this posting is NOT about a linear letting me down. It is about me trusting a radio to transmit a low power output, and me taking too many risks by assuming that it would behave itself.

I have tried to write this piece several times, but it looks as if I am blaming the linear, which I am not. I will keep going on about that, just as I go on about lots of things in this blog.

Icom IC-7100 "It was him what done it, Constable".

There is a risk using modern high gain solid state amplifier devices in amateur service. Due to the enormous gain available the danger is that it will prove impossible to reliably restrict the RF power supplied to the device. The attenuator built in to the linear has to be set at a level compatible with the radio, and thought has to be given to the possibility of a sudden RF spike over-driving the device and its supporting circuitry.

So the spike in this case was generated by the Icom IC-7100 (or possibly the computer too) and that caused damage to the linear. Multiple spikes over a long period, or so it seems. How could I let this happen? Well one factor is that the IC-7100 has been operating into other linears with higher value attenuators for years. These larger attenuators make the chances of overdrive are much less. As a result I had become lulled into thinking this was not a big issue.

I have been thinking about this type of thing for a long time. The same problem arises with transverters as I explained here back in 2019. In fact I was extremely careful with transverters and even then I managed to over-drive the attenuator in one of them, though in that case without any calamitous results. It seems as if I failed to learn that lesson.

When it comes to VHF and above the amplifier has the RF power on hand to destroy any masthead preamp or other device further along the chain, and that also has to be factored into the equation.

Despite all the knowledge I had, I still managed to over-drive my linear despite having set the "RF Power" control to the correct level. The simple cause was that I had relied on the ALC operated "RF Power" control to keep the drive power low at all times.

If the RF driver relies on using the ALC circuitry to limit the output power, the chances of a random power spike are quite high. Connecting this transmitter to a computer which has its audio turned down and expecting that level to be uniform is another risk in the chain of potential for over driving the later stages.

At this point I can hear a voice over my shoulder saying that valve linears are much more reliable. You know who you are. Well, maybe. Not necessarily if you take care and if your linear is carefully designed, as this one was. I have three solid state linears which have given more than five years trouble-free service. And some that didn't.

So here I am talking about my Tajfun 1000 500W 2m/70cm linear. I do not think that it was in any way at fault in what happened. Neither was the excellent SHF-Electronik MMV 432-VOX masthead preamplifier which went arrrggghh at the same time. Nope, it looks like RF spikes from the rig that caused the problem.

I have to say that both the suppliers, VH Electronics for the linear and SHF-Electronik for the preamp, could not have been more helpful in fixing the consequences. Aside from the postage, the charge was €70 for the linear and €7 for the preamp. From this you can conclude that it was not the main RF device which failed in the linear but simply one diode.

Tajfun 1000, the victim of the problem, not a problem itself

This is not a review of the Tajfun, a linear amplifier which I think pretty highly of. It is very difficult to photograph as it is glossy black on the front and the display panel is pretty bright so it presents me with a technical problem when it comes to making an image of it.

Anyway, moving on to fixing things, ...

The fault showed up when suddenly the Tajfun lost output power and the preamp suddenly had more gain when it was out of circuit than when it was in circuit. Something had happened.

At this stage Vlado at VH Electronics, who had supplied the amplifier, went to great lengths to try to diagnose the problem and fix it. Thanks to the nature of the design, a lot of things could be fixed and indeed updated over the internet. The software for the display was sent to me and I was able to re-load it on a new SD card, and then the same was done for the firmware for the control board. These things helped but did not solve the underlying problem. After eliminating the relays and cabling, the overdrive had caused a fault which had to be in the amplifier RF stage.

Another clever thing that Vlado was able to do was to interrogate the records of overdrive and power output warnings which are stored in the control system. From this we discovered that the Tajfun had (successfully) coped with a series of huge overdrive situations. The output produced by the linear was at least 10dB above the power settings I had used and 3dB more than the full peak power the linear was rated at. Running any linear at twice its rated power is asking for trouble.

In each case the Tajfun protection circuit had cut out as it should have done. However, it was clear to me that this was not me deliberately operating at these ridiculously high power levels but probably something which was momentary. I was setting things up for 200W output so it was not that which was the root cause of the trouble.

The control circuits cannot generate more power than the transmitter can produce so the basic fault had to be in the transmitter. I will deal with that later.

For now I need to say that once he had eliminated all the other possible causes Vlado asked me to send the Tajfun back, which I did. The Freescale device had survived running at twice rated power, and the power supply had coped with supplying the necessary extra amps. Obviously, this overdrive was indeed  momentary. Vlado quickly identified a diode in the bias circuitry and the linear issue was fixed.

ITB RF board inside the Tajfun 1000.

The Freescale MRFE6VP5600H device is in the centre of the photo under the alloy plate, firmly screwed down. At the time of this photo I had tagged on a direct co-ax feed at the bottom of the board, bypassing the relays to check that they were not at fault. This also bypassed the attenuator which can just be seen below the red wire, bolted to the bottom of the RF enclosure.

Early in our search for the fault Vlado had considered that the attenuator could be at the root of the issue. While he had the machine with him he wisely changed the attenuator for the most recent version, increasing the power reduction from 5dB to 6dB. We could find no evidence that the attenuator was at fault, and anyway it seems to me that it would be unlikely that it would fail momentarily, and then recover, several times.

I have nothing but praise for the Tajfun. Having been all round the inside of it I can say that it is carefully designed and well made.

So the Tajfun returned and quickly resumed producing the power I was looking for.

You cannot overdrive any linear, not even a good one.

Siggi at SHF-Electronik quickly repaired the preamp which had been driven with 6dB more than it was rated for. Once again, not the preamp's fault. The service offered by Siggi remains exemplary. It took me a while to get around to dealing with the preamp, and in the meantime I had replaced it. He fixed it and returned it very quickly, and now I have two 432MHz preamps.

Even I cannot use two 70cm preamps. 

I need to thank Richard GI4DOH for helping with the logistics of getting the linear repaired by Vlado. I will not go into the details, but Richard was key to resolving the whole thing.

The fundamental problem was my Icom IC-7100. Well, that conclusion is inescapable. This was the source of the RF drive which blew both devices. I have had spike problems before. I had grown complacent.

I had connected the IC-7100, capable of delivering 35W on 432MHz, and set the output power to 4W as that was what the linear needed. The possibility of the rig delivering a sudden +10dB spike may sound improbable, but actually the full rated input of the linear at 500W peak would have required just 10W to achieve. Anything over 10W would have pushed it too far. The evidence would suggest that it reached 20W at least.

So what to do next? I do not want to have fixed the Tajfun and preamp just to overdrive them again. 

I could have replaced the internal attenuator in the Tajfun with one of a higher value. That is the solution adopted in my Gemini linears which are set for 25W drive. However, I was reluctant to raise the value of the attenuator too much as the heat dissipated has to go somewhere and the linear generates as much heat as we might expect already. Also, what if that single attenuator fails?

In the end I decided to add a second attenuator in the tx line. The idea was that I could change the value if necessary, and move it outside the linear for cooling if that was needed too. Doing a few sums, it looked as if a 5dB attenuator would involve the drive increasing from about 4W to about 12W for 200W output, and leave 8W to be added to the heat inside the Tajfun. The Tajfun has efficient temperature controlled turbo type fans. This means that any spike would be reduced by 5dB, and the result would not over-drive the linear or the preamp.

Additional attenuator which is now fitted inside the Tajfun 1000

Then I have considered other ways of avoiding the spike in the first place. The big problem here seems to have been me relying on the ALC to limit the power into the amplifier. One of the points made at the launch of the IC-9700 suggested that it has a "true power limiter". This appears to be the "TX PWR LIMIT" control. It is in addition to the "RF POWER" control which seems to be a standard ALC-type limiter. I say "appears" as this is not clear in the manual which states "The Transmit Power Limit function limits the output power to the preset level for each band.".

Anyway, the worry I have with this is that if anything did go wrong with this (for example if I messed up the settings) the IC-9700 can deliver 75W into the linear as opposed to the 7100s max of 35W. And, yes, I can get settings wrong.

I am guided by the idea that if something can go wrong, it will go wrong. Years of being steeped in statistics and probability have taught me the validity of that old saying. However, I can also get too carried away. It is not very likely to go wrong. Adding 5dB attenuation to the linear still gives some protection. If I remain worried I can increase the second attenuator and help cooling by placing it outside the amplifier casing.

In any case, I am losing confidence in the IC-7100. The years roll on and new better designs appear. It now looks pretty dated as a superhet radio in a shack full of SDRs.

73 

Jim GM4FVM