Thursday, 5 June 2025

3 and 4 June 2025 - Sporadic E +++

It has been suggested that sometimes I talk nonsense. In fact Mrs FVM has suggested this and not mentioned the word "sometimes". I asked her for written evidence but this request seemed to only make things worse for some reason.

Anyway, had she gone back to 7 May on this blog, she would have found me waffling about the dearth of opportunity on 70MHz. By 3 June I can accept that this was ... well ... maybe a bit strong. Not quite nonsense but not quite correct either. Possibly incorrect by several orders of magnitude. I might describe it as "striving for the truth".

On 3 June I worked 35 stations on 70MHz. Despite my earlier gloomy predictions about Italy I added the long missing square in Piedmont and extended my coverage south to Naples by adding the next two southern squares. There is still ground to cover in Southern Italy but I have at least made some. I heard a station near Bari but failed to work him, and there was even somebody in the missing square in Northern Sardinia. So there is still hope. Jumping between 70.154 and 70.190 seems to be the order of the day on FT8, with 70.200 for everything else.

It is not just Italy. My 2025 DXCC worked on 70MHz total has risen from seven to 17 (one day later it was 21), while the 70MHz all time squares total now totters at 299, needing just a nudge to get it over that significant figure.

And that was the way I would have started this posting if it had still been about 3 June only. The K number was high on 3 June and Sporadic E was everywhere.

GM4PMK magnetometer for 3 June 2025
But then for 4 June it was also pretty active.
GM4PMK magnetometer for 4 June 2025

Now I am not about to get into a debate about whether the K number as shown on the magnetometer has got a direct relationship to the intensity of Sporadic E. All I am showing is that the two things seem to have coincided. Please draw your own conclusions. Lets just say that the next morning the magnetometer was much more stable, and there was also very little Es to interest me. 

I doubt if it is a direct relationship but I am curious as to what other relationship there might be.

So now this posting has started covering both 3 and 4 June. Over those two days I had 78 contacts all but one involving Sporadic E, either single or multi hop. The one that didn't was a tropo contact to GW on 2m (adding GW to my 2025 DXCC total).

On 2m there were Es openings on both days. On 3 June this was to  E7 and YU, while on 4 June to I (13 contacts), HB (3), DL (2) and 9A. A third opening to IS0 sadly produced no contacts for me.

144MHz contacts at GM4FVM on 3 and 4 June 2025

Adding to the 70MHz 3 June report above, 4 June was almost as dramatic.

70MHz contacts at GM4FVM on 3 and 4 June 2025

With all this activity I had little time for 50MHz. Mike, GM3PPE, had given me a tip off about 9J2FI's operating times and I was ready for him when he came on. Zambia was new country on 6m so thanks for that Mike. Earlier I had worked ZS6NK and I guess that both of those were TEP with Es linking. I managed a couple of trans Atlantic contacts on 3 April but I had to cut the session short that day with a lot left to work. On 4 April there was an opening in the evening to South America. I failed to reach LU, and there were a lot of PYs at one stage when I could not manage to call them. There was plenty more I could have done on 6m but the other bands kept me busy. After all, contacts on each higher band count for double points. [Still don't know what that means Jim but you keep writing it].

50MHz contacts at GM4FVM on 3 and 4 June 2025

So what did I learn from making 78 contacts during those two days? 

Well, with the aurora the day before (see here), this event was long lasting. Sporadic E is probably caused by multiple factors so simple answers will probably never solve the mystery of how it arises. Whether you think that solar activity short of an aurora is a factor is up to you. However, it seems to have something to do with it. Obviously the annual increase in solar radiation is behind the basic seasonal effects, but then the dramatic day to day changes must have some other cause. Could this be linked to the K number? There is not always Es when the K number is high, but then multiple-factor events are like that. Could raised energy levels of solar particles during storm could tip the ionosphere over into Es when otherwise it is just below the threshold?

Whatever the answer to those issues, the sporadic nature of Es makes for an exciting time when it decides to arrive. 

Anyway, this is what a busy day looks like when there is 144MHz Es about:-

DX Maps on 144MHz on 4 April 2025

Who said that VHF is for local contacts?

And here is 70MHz during an Es opening. There are now 4m amateurs in many parts of Europe and there is still some OIRT broadcast reports to show us what we could do if only we had more access to the band.

DX Maps on 70MHz on 3 April 2025

And now the question is : what is next?

73 Jim

GM4FVM

Tuesday, 3 June 2025

2 June 2025 Aurora

I am not sure how to define DX. Obviously it depends on the band in use. As a generalisation I might define it as stations I can contact which I would not usually be able to reach. This handy definition covers those situations where the activity is low as well as places where the propagation usually prevents a contact.

During the auroral opening from here on 2 June 2025 my understanding of this was a bit stretched. Some of the closer at hand stations I might have worked on a slightly raised tropo day. On or two I might have scraped through to on flat band conditions, but the result would have been scrappy. However, yesterday they were not just workable but they were all out loud on the loudspeaker. I might add, distorted and muffled on the loudspeaker --- but definitely loud.

There was plenty of early warning of this aurora.

Solarham warning of likely auroral activity on 1 June 2025

Despite the shockwave arriving on 1 June, the main effects of this strong solar event did not produce the desired result here until 2 June. I was listening on 1 June and it seemed as if I had missed the action, but the NOAA predictions showed activity extending over three days.

NOAA predictions for 1, 2 and 3 June 2025 made on 1 June 2025

It is quite possible for there to be a high K number at one stage but for the polarity to be moving north, in which case no enhanced conditions apply, and then for the polarity to head south and the band to open later. As it turned out, the magnetometers continued to see-saw during 2 June and conditions suddenly improved.

GM4PMK magnetometer on Mull, showing 2 June (top) and early 3 June (bottom)

I first tried 50 and 70MHz after around 11:00 without result. I could see people making contacts but there was not much happening here. I sometimes look at the FT8 waterfall while beaming at about 30 degrees, and if that shows dispersed traces something is happening. I could see MM5DWW on Orkney ranging in and out of auroral propagation on 50MHz. Sometimes I could copy him on FT8, other time his signal was wide and sounded auroral.

I could not raise anyone on either 50 or 70MHz. However, I had been watching DXMaps and I saw that various Russian stations were making contacts on 144MHz via aurora. Oddly they were posted as JT65 but the text said they were Q65c. They were also appearing on PSK reporter as Q65. So, more in hope than in expectation I went to the frequency they were listed as using (144.116MHz) and tried calling. No result. 

Due to the rotation of the Earth relative to the Sun, the effect of the aurora varies over time. This produces the "auroral oval" which is like a collar around the poles which varies in thickness. Usually the oval is thinnest in the mornings and as the Earth rotates the thicker sections appear to the north of me. In this case due to the high level of solar activity the ovals were predicted to be thicker than usual and therefore strong, but I still needed to wait for the widest portion to approach my part of the world.

Prediction for auroral oval for 1 and 2 June 2025

Note that these predictions made at around 05:00 show the aurora extending well down into the United States, while GM is at the back of the globe where a thin to non-existent thickness of aurora exists. In such situations there is nothing for it but to wait for the Earth to turn and bring a thicker part of the oval into my area of operations. This often happens in the early afternoon. Note also that the oval is very large, so this was clearly a major event.

It is often possible to wait of a thicker part of the oval to arrive, only to discover that the polarisation has gone against me by then. On 2 June, though, it went well.

I was listening on 144.116. This seemed an odd choice, but that was where the Russian activity was. Having said that I decoded nothing to start with. About to give up I heard something on the loudspeaker. Pursuing this, I had to turn the beam from my usual 30 degrees to 54 degrees before I found PD1BHZ calling CQ. After that contact I worked 16 stations on Q65-30C, all with the characteristic distorted auroral sound. These were 5 x PA, 4 x G, 4 x DL, and one each of EI, OZ and ON. Best DX was to Ronny DL1RNW in JO62, at 1039km. The event ended here at 17:15.

144MHz auroral contacts at GM4FVM on 2 June 2025 

Map made using  K2DSL mapping. As usual click images to enlarge if necessary.

Whilst none of this involved excessive distances, it was still very interesting. Most contacts were between east and south suggesting that the oval was indeed wide. Usually in smaller events the oval is further north and contacts tend to be more northerly. Also for the same reason the azimuth was further south than usual, between 40 and 54 degrees,whereas usually 30 degrees or less is what I find best. The benefit of reaching this area is that there are a lot more stations than to the north where I more often work.

DX, to me, is not solely determined by distance. These were stations I could not have expected to work so that is good enough for me. 

All in all an interesting opening. Although the predictions suggest the chance of another event today, I am not sure. It is that type of uncertainty which makes VHF DX-ing interesting. 

 73 Jim

 GM4FVM

Tuesday, 20 May 2025

Multi-hop Sporadic E opens up again this year

I follow Sporadic E not just to have many interesting QSOs, but also to lead me to some meaty DX. Unlike some others, I do not claim to have ever worked F-layer DX on 6m. They have done well to do that, but it has never turned up at GM4FVM. At least, not anything that I can feel confident to claim as F-layer propagation. So I rely on Es to link into something else (like Trans Equatorial Propagation TEP) or allow some Multi-hop Es.

And so on 17 May I was on 50MHz having a good time working a few European stations. Around noon I worked a couple of French stations and it was notable that the "searchlight" area was very small and I could only hear one station at a time before the propagation moved on elsewhere. 

After 19:00 I had some nice QSOs into Spain. At 19:32 while trying to work Fidel, EA1HRR, who faded out, I noticed that I could hear ZD7BG. This was a fairly remarkable step up in distance, from 1387km into IN83 in Northern Spain to 7922km to reach IH74 in St Helena. And yet I still believe that this was Sporadic E and all that had changed was that I had tapped into multiple hops.

50MHz contacts at GM4FVM on 17 May 2025

I have used K2DSL's mapping above and you click to enlarge if needed. 

So why do I think that this was multi-hop Es rather than the other possibilities? Well, the solar activity at the time did not suggest that F-layer propagation was possible on 50MHz. It could have been TEP but as I am at 55.8 degrees north this would need Es linking. Possibly it was TEP, but the sudden arrival and departure of ZD7BG is more typical of multi-hop Es. A path of almost 8000km means most likely there would have been four hops. The distance is much the same as other long distance multi-hop Es contacts which I have had, for example XE2JS, definitely not F-layer in 2018, at 8200km.

ZD7 was a new DXCC for me on 6m, number 127. I had tried before but this was my first success. Some other GMs did work him that evening before he quickly faded out. That was it for me on 17 May - five European contacts, this one, and then silence.

There have been other remarkable contacts I have had over the years which defy categorisation. A notable example is the propagation to Japan and China, mostly in June each year.  Although this was initially taken to be a newly discovered mode of propagation, most sources these days suggest that it is another, unique, form of Multi-hop Es. Then there was the remarkable DX which many of us worked last October and November. This covered a large area from India, across the Indian Ocean and as far as Australia. What that was I have no idea, but it did not have the characteristics of F-layer, nor did it seem to fit the normal pattern of TEP. Now, will that happen again this year?

73 Jim

GM4FVM

Wednesday, 7 May 2025

Summer Es begins, but where to go on 70MHz?

I just increased my country score on the 4 metre band for this year by one. The new country for 2025 was Scotland. Although I worked my home country on 6m, 2m, 70cm and 23cm much earlier this year, it has taken me until May to work it on 4m. This was a tropo contact, as Dale, MM0INH, is 44km away.

Over on 50MHz the summer Sporadic E season has started and I added to countries to my annual list today, Lebanon and Algeria. That brings it to 40. No Es yet on 4m, so  the total there so far this year is now ... seven.

GM, G, EI, HB, DL, OZ and S5.

Of course working Es on 6m is easier than on 4m because the season is longer. Also, not so many DXCCs have the use of the 70MHz band. But even taking this into account, I have struggled in recent years to work much exciting stuff on 4m.

I guess that one of the reasons why I have liked 4m is that the going is hard. For about 50 years I have avoided bands like 20m because it all seems too easy. On 4m you have to use your wits to get anywhere.

And yet, having chosen this bed-of-nails path for decades, I am now getting a bit disillusioned with 4m. Possibly because I have achieved most of my goals ... I have reached 55 DXCC enities, as far flung as Western Sahara, Kazakhstan, Kuwait and Cape Verde. This would have been unthinkable when I started on 4m when six DXCC was exceptionally good and eight was the maximum possible.

There is still plenty to do, with possibilities in the Caribbean and the long sought after Greenland. Possible, certainly, but very unlikely to happen.

If I have reached a fair number of countries what about squares?

Squares worked at GM4FVM on 70MHz up to 7 May 2025

I am closing in on the final squares left for me to find. For this purpose I tend to exclude the watery squares which rarely appear - if I work them, great, if not then I will press on with the likely candidates.   There is still one on the Scottish mainland to reach, plus the one covering Shetland. There is one in Ireland that looks like a reasonable possibility, plus one in Cornwall. Then there is the elusive square in Portugal and four more in Spain - these are places with low populations. Likewise, there are many in Norway, Sweden and Finland to reach, and hopefully Mek, SP7VC, will activate some of these this summer. Italy south of Milan is undone, as are Northern Sardinia and Eastern Sicily. 

Of course France and Austria are not done as they do not grant access to 70MHz, though in Austria's case I have worked all the squares except one thanks to contacts with surrounding countries. What are the chances of these and other countries will appear soon? Not much I think. I have been surprised in the past when other DXCCs arrived on the band, so maybe. I could be surprised again. But Turkey, Belarus, Ukraine and Russia? Not a hope really.

If I was to set a target for all-time new squares for 2025, I would think perhaps 5 or 6 to add to my current total of 296. Why so glum an outlook? Well, activity on 4m seems to have declined in recent years. During the last meteor shower I heard nobody on 70MHz. On the last aurora opening activity was very low. FM locally is now dead, shutting off the chance of the odd DX contact there too.

Is it just me? Have others lost interest in 4m resulting in fewer contacts? This is hard to prove but I think so. Most of us have lost the personal touch which 4m had when we used SSB and CW. Data modes are effective but rather soul-less. There was a sense of camaraderie when we had to either build our own gear, convert commercial equipment, or rig up transverters. 

There is not much scope for technical improvement. I am still using much the same outfit as I was ten years ago - Icom IC-7100, Gemini 4 amp running 150W and a five element yagi. This has much the same performance as the gear in use during the previous five years too. I cannot see any point trying to improve on it. It is not that I am unwilling to improve it, it is just that there is not much further to go, technically or in distance.

I am not about to give up on 4m. I will try to concentrate on my improving annual DXCC list rather than my all-time one. It should be easy to get beyond seven (!). All-time new countries would be very nice, but I cannot count on any turning up. I will continue to use 70MHz as a warning sign that Es may be rising up from 50MHz towards 144MHz.

However, for me somehow the recent silence has taken the edge off this interesting part of the spectrum.

I hope that the radio gods soon dispel my lack of enthusiasm.

73 Jim

GM4FVM

Saturday, 19 April 2025

A long lasting tropo event and then an aurora

After 3 April 2025 and the noticeable tropo duct mentioned in my last posting, there was a long lasting tropospheric event caused by a stable high pressure moist air system over the North Sea.

Long lasting stable high pressure systems are not always my favourite events, as it is normally alterations in pressure (usually downwards) which tend to produce openings. This was actually two systems, as when the first started to fill the second one moved in and merged. It appeared to be one high pressure system the whole time. 

I worked 53 stations on 144 and 432MHz between 1 and 11 April. This despite being absent at the GMDX convention on 5 and 6 April. The pressure was raised but not very high, peaking here at at 1026hpa on 10 April, but it had maintained a steady level above 1015hpa all the time since 30 March. In an area much given to storms arriving from the South West this long period of high pressure is unusual.

What constitutes "DX" for this purpose is debatable. Let us not have that debate here right now.

I have tried to plot contacts against barometric pressure as this event progressed over two weeks.

Week One - 

Barometric pressure at GM4FVM 31 March to 5 April 2025

As usual, click to enlarge images as required.

Where only a prefix is shown, just one station there was worked. Where a number is shown, e.g. 3xSM, this means three stations were reached in that prefix. A dotted line under the prefixes indicates that a contest was scheduled for one of the bands for a time during this period.

The barograph chart at GM4FVM shows the raised pressure during the week. Please have patience with me while I use up imperial measurement charts - I will properly calibrate the instrument once I have changed over to charts in hpa units.

The gentle rise in pressure up to the afternoon of 1 April produced no improved propagation. Then a very slight levelling out of the rise brought two OZ stations and a G who were all involved in the 144MHz NAC contest. The rise returned on the morning of 2 April but levelled out again in the evening. That level stretch brought a good opening to OZ during the 144MHz UKAC FT8 contest. Another slight dip in pressure coincided with the SM duct on 3 April (see last posting) and continued into an opening across the North Sea on the morning of 4 April. This ended with an short but steep rise in pressure, while the usual evening enhancement brought in mostly Gs and PAs towards the end of the day. On 4 April I worked 2 x LA, 3 x OZ and 3 x GM and one SM in the morning to afternoon period, plus 4xLA, 5 x G, 6 x PA and an OZ in the evening.

I was absent from the shack as I was away at GMDX on 5 April and almost all of 6 April. Actually I was home around lunchtime on the 6th but I then fell asleep - which must have shown the quality of the contributions I heard at the GM convention.

Week Two - 

Barometric pressure at GM4FVM 6 to 12 April 2025

During Week 2 the pressure gradually rose to a peak on 10 April and then fell steadily until 12 April. It was possible to work OZ on many days, and during the 432MHz NAC contest on 8 April I worked 6 OZ and 2 SMs. The 432MHz FT8 UKAC on 9 April produced a better than usual number of contacts. Once the steep decline set in at around 10:00 on 10 April I only worked one more DX station when the fall levelled up slightly.

Looking at these charts I would suggest that things depend on three factors for maximum DX for me on 144 and 432MHz (and probably 1296 too) 

EITHER

1) High pressure with moist air (ideally with gently declining pressure)

OR 

2) Evening cooling after a day of moist air high pressure

OR  Both

PLUS

3) A contest

It looks very much to me that either 1 or 2 or both is very desirable, but adding a contest really raises my DX performance. Not that I enter contests, but I do give away points. Mornings generally are not so good, and there are few morning contests except poorly supported ones at the weekends.

Basically, if the same opening had occurred at the end of the month when there are no contests on 2m and 70cm I think I would have fared much worse.

The fact that a contest makes so much difference was something I must have been aware of but I had never put into context. It seems to be a bigger influence than I would have expected.

By the way, the rather wobbly barometer trace is not due to the apparatus but due to my shaky hands. I went over the trace with a pen as the barometer leaves quite a faint mark. I am using a modern felt-tip pen on the barograph, but the line gets lost amongst the chart lines. Charts used to be in red ink so that you could see the trace more clearly ....

Dickson and Cargill Barograph at GM4FVM

Mind you, the barograph is 100 years old. It came to me via my father and it had not worked for at least 60 years. Although of no value I restored it recently. It is a useful thing to have for a VHF-er. I do have a modern weather station with a pressure readout but that will never be the same.

And then on 16 April came an impressive aurora. The K number at GM4PMK's magnetometer briefly reached a rather impressive K=9 and the VHF bands sounded amazing.

GM4PMK's magnetometer chart for 16 April 2025

I did a lot of listening. I did not work many stations compared to some others. I stuck to Q65 and contacted 12 stations, 7 on 50MHz, 1 on 70MHz and 4 on 144MHz. It would seem that the trend is continuing for Q65-15C to be common on 6m while Q65-30B is gaining ground on 2m where the going is rather more difficult.

Based on the present stage of the sunspot cycle many crystal-ball gazers are predicting more aurora activity for the coming months.

73 Jim

GM4FVM






Thursday, 10 April 2025

A classic tropospheric duct

I really enjoy working tropo enhancements on VHF and UHF. Usually though they move around with the weather and can be quite wide, which makes them hard to identify against a complex background of other contacts.

However, on 3 April I stumbled across a long lasting and quite narrow duct on 70cm. The background is that a high pressure system had developed to the north of Scotland and was destined to affect our weather for ten days or more. Seeing the opportunity of the good weather, I had scheduled some antenna work. As barometric pressure was moderately high but not declining I though nothing much would emerge on the tropo front. Usually good conditions emerge only on the trailing edge of high pressure systems, when pressure is falling. However, even during long lasting highs it is possible to find good conditions.

With all this in mind, and while working on my 2m antenna, I passed the shack door on the way to collect some tools. I noticed a very strong station calling CQ. This was SM6VTZ in JO58.  I have worked Chris a dozen times on 23cm, 70cm and 2 metres over the past four years, but only during good conditions. The striking thing about seeing him on the waterfall this time was not only how strong he was, but that nobody else was to be seen. Apart from one station, conditions were normal.

Although he had finished calling CQ, I called Chris at 12:49 and gave him a +20 report, and he replied with +23dB. The path length is 879km. These are not unusual reports, the previous time we worked on 70cm was in September 2024 when the reports were +14/+29dB. It is worth bearing in mind that during normal conditions I cannot hear Chris at all and on a flat band I can usually work only about 300km with much lower reports.

What was different about this contact was the almost complete absence of any other station, not just on 70cm, but also on 23cm and 2m. Chris came on to KST chat room where other SM stations reported hearing nothing from me.

On KST Chris and I exchanged reports as the duct built over time, later reaching +24/+34dB. Having started before 12:49 this went on until after 16:50. I heard SM6CEN in JO57 at 15:19. I guess that Hakan is on the southern edge of the duct as signals to him were much lower at  -19/-16dB at a time when VTZ was reporting my signal via KST at 50dB higher than Hakan.

I also worked MM0INH who I think worked VTZ too, but at lower signal strengths than I did. Dale is 43km to the west of me. I was not aware of any other stations working Chris though he may have worked another station in North East England. It is clear that this duct was narrow.

Extract from station log at GM4FVM covering 3 April 2025

Click to enlarge images if you need to.

So how do I know that this was a narrow duct? Because it follows the general pattern for ducts:-

1) I did not work anybody else on 2m, 70cm or 23cm that day, and I would have expected to if this had been a general enhancement or a moving or wide duct.

2) It was extremely stable over a long time - several hours

3) Stations outside the duct did not get into it 

4) Signals were extremely strong as ducts pass signals very efficiently 

More usually ducts move with the weather. On this occasion, with a very stable weather pattern, it stayed in one place. I have experienced this before, but it is unusual.

Here is the best map I can do at the moment. In the absence of Log Analyser I have used K2DSL's "ADIF to Map" site. Once I had the map by this method I went back to the way I made maps years ago - passing the image through two pieces of software to add text and crop to size. I am still seeking a better solution.

Contacts at GM4FVM during 3 April 2025

Ducts are common. What was uncommon this time was finding such a narrow long lasting duct, with no other DX possible for the whole day. I like ducts, and after all it was a duct which allowed me to work EA8TJ on 5 August 2018, a distance of 3260km. But others in various parts of Scotland could access that duct, whereas this time it was very much narrower.

I shall look more carefully for such things in future. And next time I will try to remember to ask Chris to try 1296MHz too.

[EDIT. I should have mentioned that in contrast to this narrow duct, the next day I also worked SM6VTZ, this time on 144MHz. Unlike 3 April, contacts on 4 April were all round the compass and nothing like as strong. I worked 15 on 144MHz and 9 on 70cm, spread almost evenly around the North Sea. 5 x G, 4 x OZ, 5 x LA, 3 x GM, 6 x PA and one SM. That could hardly have been more different]

73 Jim

GM4FVM

Wednesday, 9 April 2025

Log Analyser de-activated.

[Edit - this may not be the final word on this - see update at the bottom]

Sad news from Mario DL4MFM that his excellent Log Analyser has been de-activated because Google no longer offers the map without charge.

This is an unfortunate development for me as Log Analyser was a very useful tool to use for this blog, as well as a very handy way of understanding QSO data.

I have written to Mario to thank him for a number of years of great work. Log Analyser developed over time and added some very useful features. He deserves our thanks for all his work.

It is a pity that another map source cannot be used - such as OpenStreetMap. In any case I would be willing to pay a subscription to a similar service if I could find one as good as Log Analyser.

Moving on, I am tinkering with GridTracker which is very good for all sorts of things but which does not quite match Log Analyser 3.2 for the functions I need. It may do for the meantime, and there are a couple of others around. We shall see.

I miss Log Analyser though.

73 Jim

GM4FVM

[Update - Mario has replied to me that he is hoping to bring Log Analyser back, perhaps with MapBox mapping. However, he has other commitments and this might take time. I am prepared to wait for such a useful aid. I have thanked Mario once again for his efforts to date. 73 Jim]

Friday, 14 March 2025

"Understanding VHF Propagation" by Rohde and Schwarz

Thanks to John, EI7GL, for posting details of this YouTube video. Anything which suggests that VHF propagation is almost never "line of sight" is OK with me.

A link to John's site is on the side bar. It is a very useful place to look for the VHF enthusiast. 

Cover image from the presentation. See links below.

OK, so some of us think we might already know something about this topic. Maybe. But I certainly benefitted from seeing some things in a different context. Others may wish to look at it.

I learned that duct widening causes lower frequencies to be included in tropo ducts as time goes on. Now I had experienced that tropo ducts are "downwards" (I heard them first on higher frequencies, say 1296, then 432, then 144MHz over time), whereas sporadic E is "upwards" (starts on 50, then 70, then 144MHz). What I didn't know was why this applied to tropo ducts. So I learned a few things.

I knew that sometimes raising my antenna can lose a duct, whereas other times it can get me into a duct. So I had no idea that there were two forms of duct (surface and elevated), and now I know what that might mean for me.

It was good to see it suggested that because no certain mechanism for the sporadic appearance of Es events exists, then prediction of Es events will be a pretty futile exercise.

And it was also good to see a correct time for peak meteor activity. The presentation agrees with the texts that from about 04:00 to about 08:00 local time is the best (not "around dawn" as some sites say, which is too limited even this far north).

So I learned some things, and some things were confirmed, and some things were reinforced.

This video is not intended for radio amateurs, but it does a good job for our hobby nevertheless.

If you are interested you can find it by searching YouTube for "Understanding VHF Propagation" by Rohde and Schwarz.

I will try to post a link here too  https://www.youtube.com/watch?v=DTXJ3bS2UcE

73 Jim

GM4FVM

Friday, 28 February 2025

Fifty years an amateur started here

 On 4 February 2025 I reflected on this being the 50th anniversary of me becoming a licensed radio amateur.

I have already explained at very great length here https://gm4fvm.blogspot.com/2018/09/vhf-1970s-style.html  what I was confronted with once I got that licence. This posting is about the exam itself.

The run up to this was 10 years as a short wave listener, building crystal sets (and more) from Philips and Sinclair Radionics assembly kits. On 2 December 1974  filed into a hall in London to sit my Radio Amateurs Examination (known as the RAE). I cannot recall now, but I think the hall belonged to the City and Guilds of London Institute, the body which ran the RAE in those days.

I had not taken the precaution of having any formal training before taking the exam. I was self taught, apart from Physics lessons at school and reading several books. I recall "Understanding Amateur Radio" from the ARRL, a book which seemed out of date to me at the time. I bought it second hand and still have it. Back in 1974 we had the choice of drawing valvised or transistorised  circuits in the RAE, and my preference was for the valve versions - the ARRL book was from the valve era and that was what I was learning.

That day in 1974 a total of 720 candidates sat for their RAE in various examination halls all round the UK. Of the 720, 475 would pass the examination. At 66% the pass rate was not too bad. Looking around me, although I did not know anybody, I did wonder who might pass. They all looked fairly well prepared, and I was not. Still, the Institute did allow you to use a set of logarithm tables, which I doubt would make much sense to current candidates.

Back then there were two formal exams each year. In May 1974 a further 1719 had taken the exam. Traditionally the May exam came at the end of a formal course of evening classes over the Winter and the pass rate was slightly lower at 62.9%. Some people re-sat the exam in February after failing in May, so the pass rate in February was often marginally higher thanks to people who were trying for a second time. 

In 1974 a total of 1506 people passed the RAE. The number passing had been about that figure each year since around 1968. Before that it is hard to generalise. The RAE was introduced in 1946 and in the early Post-War years a lot of amateurs qualified for a licence without taking the RAE thanks to military service in a related trade. After 1978 there was a bulge in numbers which is usually put down to a craze for CB introducing many to radio. Anyway, in 1982 more than 8000 qualified before a long decline until in 2002 the figure fell to under 300. The last RAE was in 2003, after which changes took place and eventually our current multiple choice tests and the three tier system emerged.

The RAE in my day consisted of a three hour written examination starting at 18:30 in the evening. There were two parts - Part One had two questions, and both of those were compulsory. Part One was about licence conditions. In Part Two you could choose to answer any six out of eight technical questions. This meant for me that I could avoid my two weakest technical subjects by picking the right questions in Part Two.

Part One carried more marks per question than Part Two. Although there were only 25% of the questions on the paper to answer from Part One, it carried 33% of the marks. In any case, if you failed either part you failed the whole exam. The idea here must have been that however technically minded you were, you still needed to know the licence conditions. 

Apologies for the quality of the exam paper below but I do not have it in a format which can be uploaded to this site. I have had to make screengrabs of an already scrappy scan. If you click and enlarge it it should be readable. In any case I will try to summarise the question in the text of this posting.

Fortunately, ten years as an SWL had made me fairly competent about the way amateur radio was regulated. Those two questions from Part One were fairly easy for me - I knew that receivers were not meant to transmit (radiating spurious signals was a big thing back then), the regional prefixes were all around me, and the phonetic alphabet was what I heard every day. From my ARRL book I knew how to filter transmitter outputs (on single band transmitters anyway). So Part One was fairly easy to deal with. 

Part Two was not so easy. I had to select two questions on my weakest areas, and then avoid them. This came down to a selection between three:-

Question Four - draw the circuit diagram of the output stage of a multiband transmitter and explain its metering. This was not great for me as I had been looking mostly at single band transmitters. In those days multiband transmitters had multi wafer band switches with rods running right from the knob at the front to the back of the rig with connections going it all directions. 40 years later I was to have a multiband SDR transceiver with only one control (on/off) and I was finally comfortable.

Question Seven - what is dynamic impedance of a parallel tuned circuit, draw a diagram of impedance with frequency and show response curves for CW and DSB. Tuned circuits have always been tricky for me. I knew how they work, I knew the principles, but a first glance this looked like a difficult one to do in detail.

Question Eight - draw the circuit diagram of the demodulator and agc of an hf receiver, and describe how agc voltage is derived and applied. I wasn't ready for this one. This had not come up in the old papers I had read. Sure I had built many receivers as an SWL, but none of them had automatic gain controls (maybe a reactance control!). I knew what an agc was OK, but I was not ready to draw that diagram.

So question eight was out for sure, and the choice was between questions four and seven as to which other one to drop. Never having built a transmitter (which SWL had?) meant that question four was clearly going to be difficult. So it was likely that I would have to try to answer question seven.

[ err, I had built a transmitter, out of the Radionic kit, but it was medium wave only and did not have a lot in the metering department. Of course, being unlicensed I never used it ...  honestly]

Right, subject to more thought later, it was time to start answering the ones I reckoned I could do.

Question Three - describe a directional aerial suitable for 144 to 146MHz and in what circumstances is a directional aerial desirable. While I had never used a directional aerial I knew how they worked (all those TV antennas all around me). Even I knew that a non-directional aerial would be better if you were expecting signals from all directions and a directional one for situations when you wanted more gain in certain directions, but then you might need to turn it.

Question Five - FM. I just churned this one out. Based on previous papers I had been expecting it. Perhaps for that reason before the exam I went round to the RSGB in Doughty Street and bought a copy of the then new RSGB "NBFM Manual". I still have that spiral bound book.

Question Six - Block diagram of a superhet receiver. I knew this one quite well and I had been expecting it. I simply trotted out the diagram of my Trio JR599. When, 30 years later, I was training new amateurs for their exam I found that I could still draw it from memory.

Question Nine - What frequency to use at 50, 1000 in darkness in winter, and 5000 miles in daylight. Meat and drink to a seasoned short wave listener. I went to town on this one.

Question Ten - resistor values in an amplifier circuit. I had not expected to see a transistor circuit but still this was ohms law and something I had carried forward from Physics at school.

So that was five done and I needed to finally decide of the sixth. Hmmm. Still a choice between questions four and seven. I realised that I only had ten minutes left so this was going to have to be a partial answer anyway. That was an even stronger reason to do question seven. I knew what the response a receiver should have for narrow and wider reception and I knew enough about impedance of a tuned circuit to have a go, though there was not going to be much detail. I just wrote what I could.

I was still writing furiously when "pens down" was called. I had managed to write for almost all of the three hour period and only paused during thinking time about which would be my sixth question.

Did my exam strategy work? Well I had expected to be able to answer six in Part Two and it should have been easy to rule out two. I found that only five were as expected and I had to choose one to answer in Part Two from those three, none of which I could do easily. However, even if I had known more about the last answer I ran out of time anyway. So that was it and we would see what happened next.

Over the years I learned how to approach three hour examinations. As I found later at university where 39% was a fail and 40% was a pass - 40% will do me nicely. I never was, and never wanted to be, a honours student. Probably because I never could be.

Somewhere in my archive I still have a the pass slip which I received from the City and Guilds in January 1975. I recall a telephone conversation with my father after I had passed. I had not even told him that I was taking the exam, perhaps because I did not think that I would pass. He was impressed by what I had done (which is the only time I recall that happening).

So I received my Class B (i.e. VHF phone only) licence callsign G8JWG, on 4 February 1975.

Anybody who has gone through the current licensing process might wish to ponder over what we used to have to do. The three hour written exam which was only held twice a year. You had to choose which questions to answer in Part Two, and you never knew what mark you got (unless you got a distinction, which obviously I did not). All you knew was whether you had passed or failed. So if you had to re-sit, you never knew what to do better.

Which question would you have answered if you had been sitting that exam? If you have sat the multiple choice exam would you prefer to do this one?

The rest, as they say on a very good podcast, is history.

73 Jim

GM4FVM

Friday, 17 January 2025

Winter - a good time for some VHF DX?

My last band report covered up to 11 December. The month after that is usually a quick decline into winter conditions. Not this year. 

The "month" from 12 December 2024 to 14 January 2025 (the FVM calendar is currently on a 33 day cycle) saw 116 QSOs to 86 squares in 28 countries with a best DX of 8620km. Nae bad? 

That was:-

70 QSOs to 25 DXCC on 6m (best DX 8620), 

10 QSOs to 4 DXCC on 4m (best 1583km),

32 QSOs to 13 DXCC on 2m (best 2811km), and,

4 QSOs to 3 DXCC on 70cm (best 408km).

Sadly, nothing on 23cm, or HF.

Let me detail how this unfolded. 

On the maps, golden pins are 6m, red pins are 2m and purple are 70cm. 4m ones do not have coloured pins, but you cannot identify them in the crush anyway.

12 December. The regular 50MHz Nordic Activity Contest coincided with the run up to the Geminids meteor shower. The result of this was very strange conditions. There was enough ionisation during meteor bursts to provide brief openings using FT8 mode. However, often these periods were not long enough to complete a QSO. Thus lots of stations were calling me and replying, but not many were actually having QSOs. I managed to work five SMs, three OHs and one YL. I had lots of attempted QSOs which failed. 

This was a very strange experience during which I called CQ or I answered CQs but many of these efforts were wasted. This made the ones that worked all the sweeter. It was hard work but great fun and I would like to try it during a shower again. I suspect that a different mode (MSK, Q65,... ???) would work better, but I had to go with the rest of the pack. I guess that FT8 was in use so that the EU contest mode could be used, ensuring six figure locators for the NAC.

13 and 14 December. This was the Geminids in full stream. Using MSK144, on 50MHz I worked SM, OH, and OZ, while on 70MHz I reached several OZs and DLs.

After a ten day gap when I only worked three stations on 2m, there was a pleasing tropospheric opening on 25 December. On 144MHZ I worked three Fs, and OZ1IIL, while on 432MHz I reached EI4ACB 

30 December. There was a good opening into North America on 50MHz, with me working 16 stations.

1 January. On this day there was a splendid auroral opening. I worked 18 stations, ten on 50MHz and eight on 144MHz. All of these were on the Q65 mode. There was some grumbling on the KST chatroom that Q65-30C is better for 2m contacts, and I am inclined to agree with that, but the 15B submode was the one mostly in use.

Auroral contacts at GM4FVM on 1 January 2025

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

Best auroral DX was on 6m where OH2BYJ was at 1572km, while on 2m SO3Z was best DX at 1297km. Once again on Q65 mode I have had far better results than I used to have on SSB or CW. Not only is the DX further, there were more contacts in more countries. 18 QSOs in 11 DXCC must surely be my best performance during an aurora.

2 and 3 January. Perhaps unusually for me, I decided to try my hand at 2m operations during the Quadrantids meteor shower, in addition to the more usual 4m. 144MHz went quite well with three contacts in LA, OH and UA, with RA1WU in KO47 being the best contact at 1853km. 70MHz was pretty good with best DX being S20OR in JN76 at 1583km. Although only eight QSOs I reckon this dual band approach worked out pretty well. I think that I might spend more time on meteor scatter in the future.

6 January. Now this was a surprise. I was about to leave the house on some sort of domestic errand when I worked VO1AN on 50MHz. Then suddenly TI2AA appeared and I worked him for a new 6m DXCC (number 125). Sometimes things like this happen and I am never ready for them. It is only by chance that I had the rig turned on and the antenna pointing in the right direction. Unexpected things happen in this hobby. 

Contacts at GM4FVM on 6 January 2025

11 January. On this day there was a general Es opening on 50MHz. I am not sure if this was "Winter Es", in which case it was later than usual, or just a random opening. Anyway, I worked 14 DXCC to get my 2025 list going nicely.

Contacts at GM4FVM on 11 January 2025

13 January. Tropo conditions were raised to the South West on this day, even though a windy weather system to the North West was stopping a widespread opening for me. On 144MHz I managed to work CT9ACF in IM12 on Madeira. I e-mailed Steve and he confirmed that the contact was complete. That is DXCC number 42 on 2m. Quite a few stations worked Steve during this opening. The hilly path to CT9 is rather difficult from here (Cheviots, Pennines, Snowdonia etc...) so I was especially pleased with that.

============================================

So that is a month at a time of year when most VHFers are winding down.

Contacts at GM4FVM, 12 December 2024 to 13 January 2025

I daresay some will be fretting now that this chart does not show much evidence of worldwide F2 propagation. I was not getting in to Asia, I was not making progress on 23cm. Hold on. Those are your concerns. I was very busy, it was all interesting and we have to work the propagation we are given. And that suits me just fine.

If the next month is half as good I will be happy.

Or even the next 33 days.

73 Jim

GM4FVM

Wednesday, 1 January 2025

Wonderful year of 6m DX - well not quite what it seemed

I read "2024 - worldwide F2 DX on 6m". Not here anyway. Good, yes. Very good, at times. But worldwide? Certainly not from here.

First, welcome to the New Year. This cheery thought is illustrated by the murky view out of the shack at GM4FVM.

Sleet on the window at GM4FVM on 1 January 2025

Anyway, back to amateur radio.

In 2023 I worked 84 DXCC entities on 50MHz. In 2024 the total was 89. This does not look like a transformational year for me. It is "good" though?

Straight away we run up against what constitutes "good" DX with radio. Do we mean more contacts, better distance, new DXCC ... ? This is an issue I have raised before. I have no answer.

[Time for some clarity here Jim]

I have tried to look for signs that there was any worldwide F2 DX at GM4FVM.

For this purpose I have come up with some sort of algorithm which would distinguish between what happens during a "normal" year and one like 2024 which is near the solar maximum. Actually, I made several scans of the data to screen out different types of propagation and measures of "good DX".

It seems to depend on which part of the world I was looking at too.

As part of trying to work out what makes a "good" contact I looked at North America

Contacts in North America on 50MHz by GM4FVM

I worked more stations in North America in 2024 (141) than in the previous 5 years combined (107). Is that "good"? Yes. Does it show worldwide F2 propagation? Not in my view. That is because though there were more contacts they did not seem to be at greater distances.

To examine this I established what areas I could work into during the years before 2023 when I could safely say that those were not F2. Then I superimposed results from 2023 and 2024 that showed that only one contact out of 199 was further than earlier years.

The QSOs themselves happened in the periods late May to early September, with a later burst in November and December, pretty much the normal pattern for multi-hop Es.

Does the analysis of the figures for this one contact look like the arrival of worldwide F2 to me? No.

Of the 141 contacts in 2024, all of which were welcome, I reached dozens of new squares. However these squares were filling in gaps between squares I had already worked (presumably on multi-hop Es) in previous years.

The map of my squares worked on 6m in North America shows that I have filled in many gaps, but the range has not increased.

Squares worked in North America by GM4FVM

A different way to look at this map is from the viewpoint of squares not worked. The range of squares worked has not been extended into the Rockies or the West.  I did not reach more than 15 US states west of Vernon in Texas. I never got to the Rockies. I did not work the West Coast. In Canada, I have not even worked Ontario, never mind anywhere further West. Surely if there had been an F2 opening to North America it would have been to those places.

The lack of an opening to the West extends well beyond the North American mainland. I have never worked Hawaii, nor any Pacific Island short of Japan.

Others may have worked across the Atlantic during F2 openings. I cannot say that I did.

Moving on to the rest of the world, lower activity levels make it harder to be certain of the various patterns. However, I found the following situation:-

South America

Most contacts in May and again in late September. Distances worked were much the same but number of QSOs was down. Overall performance was worse in 2024 than in 2023 by a factor of about 3,

South Africa/Indian Ocean

Contacts were in October/November. Once again distances worked were much the same but number of QSOs was well down. Overall performance was worse in 2024 than in 2023 by a factor of about 6,

Japan/China/Korea

Contacts were in June and July. These were much the same in 2024 than in 2023. No change there.

South East Asia and Australia

This area was new to me October to December in 2024. I had not had any 50MHz contacts there previously. As a result this was spectacularly better in 2024 than at any time previously.

================================

Having thought long and hard about all this, the only direction in which I seem to have seen F2 propagation is to SE Asia and Australia. Even then progress in this direction seemed to depend upon there being openings to Scandinavia at the same time as Scandinavian stations were working the DX. In other directions there was no sign of such long distance paths.

2024 has been very good. But the only reason why my 50MHz DXCC counts were higher than last year was because of the openings to SE Asia and Australia. Without those openings things would actually have been worse overall.

Not quite the rosy picture others seem to be painting. Perhaps it is just me...

Happy New Year everyone, and I hope that 2024 brings you health and happiness.

73 Jim

GM4FVM