The happy Mid-Summer DX time, but lots of hard work

Two of the more gripping radio spectacles at Mid Summer are the fleeting appearances of DX during Two Metre Sporadic-E and the Mid-Summer paths on Six Metres linking Europe with Japan and neighbouring countries. These are completely different processes but my operating procedures for both have evolved to become similar.

I might also add Ionoscatter, but I did not hear any this year, unlike previous years. You can read about my experiences with Ionoscatter by searching for that word on this site.

The key features of these unpredictable phenomena is that they only last for brief periods, and the stations are often only heard for even shorter periods. Basically if I blink I miss them. Having said that, if you have the time and the opportunity (and a lot of patience) you can find them fairly reliably.

What links them is that the skills needed are more akin to a fisherman casting their fly into the river than reliable radio operation. Any fisherman knows that you have to cast a lot of times before you get a fish to bite. Patience and determination are the keys to success. 

On Six Metres this path is often called a "solstice" one, suggesting that it occurs directly at the solstice i.e. 21 June (or a day either side depending on the leap year status and other factors). In practice I have found it between 2 June and 23 July. For the purpose of this analysis I am taking the path as being possible on one month either side of the solstice, i.e. between 21 May and 21 July, which is when I usually look for it. Peak time of day is often quoted at around 08:00UTC at the European end, but I have used it between 05:59 and 09:47.

As I write this on 23 July I am assuming that these propagation modes have closed for this year ... maybe not!

This year (so far) has produced these results:-

50MHz contacts at GM4FVM over 8000km 21 May to 21 July 2025

Click to enlarge images if needed, as usual.

At a detail scale you can see the spread across Japan was different on each day. The 23 June opening was to the South and West of Japan:-

50MHz contacts at GM4FVM over 8100km on 23 June 2025

Whereas the 25 June opening was the North and East of Japan, and there was no overlap in terms of squares worked:-

50MHz contacts at GM4FVM over 8100km on 25 June 2025

I posted about the 23 June opening here and for this post I have corrected a data flaw (yes, even I do get those). 

Lest this look like a simple prospect to operate I have to point out that there were only two days in that two month period when I was able to use this propagation mode. That meant 60 days sitting doing very little and 56 minutes of action across two days.

50MHz Es openings 2025 at GM4FVM
Opening	Start time (UTC)	Duration (mins)	QSOs	DXCC	Squares
23 June	08:31	29	7	1	6
25 June	07:34	27	7	1	5
Season Totals		56	14	1	11

So is all that listening for 15 contacts really worth it? Well, distances ranged between 8478 and 9216km, with best DX being to JM1SZY in PM95 square. The distances covered make it worth it in my opinion. 11 squares worked make it better, but those were all in one DXCC this year.

On two meters the outcome was different but as we shall see, the operating tactics were much the same. 2m Es can occur at any time of year but it is heavily concentrated on either side of the solstice. Openings are unpredictable, infrequent and sometimes very short.

144MHz contacts at GM4FVM on Sporadic E 21 May to 21 July 2025

This year I had 28 contacts in 7 DXCC on 2m Es. Of these, 14, half, were in Italy. The rest were Switzerland (6), Spain (3), Germany (2) and one each in Bosnia-Herzegovina, Croatia and Serbia. Distances were between 1190 and 2234km with best DX being to YU5C in KN02. There were 16 squares worked.

144MHz Es openings 2025 at GM4FVM
Opening	Start time (UTC)	Duration (mins)	QSOs	DXCC	Squares
3 June	15:44	24	2	2	2
4 June	10:19	54	20	4	13
19 June	13:00	28	3	2	3
20 July	11:38	4	2	1	1
20 July	12:57	2	1	1	1
Season Totals		112	28	7*	16*

* The Season Totals figures are lower than the individual openings due to some squares and DXCCs being worked on several occasions. 

112 minutes operation across 4 days, and then 58 days not working any 144MHz Es. Is this a reasonable result? Seven DXCC, 16 squares and 27 contacts is a good 2m outcome for me.

Around Mid-Summer, 2-metre Sporadic E occurs fairly regularly somewhere in Europe. Sometimes it happens every day for a few days. The downside is that the areas covered are very small, with the result that the chances of 2m Es happening here on any specific day are fairly low. You can of course sit and watch PSK Reporter as it shows you lots of QSOs going on (apparently) all over Europe. Sadly, these openings are limited to small areas, sometimes to just one station at each end. For those stations the opening might last long enough for one QSO, or possibly only a partial QSO. If they are lucky then the propagation will stay open at their end and move on to somewhere interesting at the far end. Or not ... for many days I can only watch as others work hard for a QSO. And then again sometimes I work a string of stations.

The Mid-Summer 6-metre openings to Japan are in some ways similar in the way stations appear and disappear quickly. The method of propagation is totally different. On 2m Es is almost always single hop, out to about 2,200km. With the Japan openings it is multi-hop and the range is about 9,000km. Calling it a "Japan" opening is shorthand as I have worked into Asiatic Russia, South Korea and China during these openings. This year, however, all my contacts were into Japan, just one DXCC.

Either way, the method of operating I adopt on each band for this purpose is different from my normal one. With stations appearing and disappearing at such speed I have to abandon my usual attempts to complete a QSO at all costs. Instead, the only method that works for me during these events is a slash and burn approach. Anyone who has ever played the arcade game of "whack-a-mole" will understand. 

Result of these short openings - MADNESS. Sometimes three stations call me, I have to pick one to reply to. Often the one I pick has gone and the other two are still calling. Do I call the strongest with me, or the one giving me the best report, as most likely to still be there in 30 seconds? 

I therefore dispense with my normal practice of sticking with contacts as long as possible in order to complete. If one does not complete, then I move on quickly to give the next one a chance. Over the years this has proved to produce the best results at GM4FVM.

I think that the very fact that I do not know when or if these paths will open is what attracts me to them. If I wanted to work stations every day I could just go to 20m. I don't like 20m. I enjoy the effort you have to put into DX on VHF and UHF. Sometimes nothing happens - some years I have only had one 2m Es contact during the whole year so 28 is pretty good going. This year I worked one 2m station twice. It is in fact unusual for me to work one station twice in a year - usually the searchlight roams widely and rarely passes over the same point.

And when it does happen the operating is fraught and exhausting. I am looking for new squares and longer distances so I have to make quick decisions as to which station to reply to. Strangely, I enjoy this part of the deal too. 

I cannot really justify the effort. I just enjoy it when it pays off.

73 Jim

GM4FVM 

I0JXX 16 element 70cms yagi

A while back I decided to run separate 2m and 70cms antennas rather than the DUAL two band one I had been using. This got me some increased performance plus the ability to put each on a different mast and spread the load between then. At the time I fell back on my rather ancient Wimo 16 element for 70cms, while I brought into use an I0JXX 8 element for 2m.

There is nothing fundamentally wrong with the Wimo other than it is rather lightly built. I had it available so I put it back into action. However, I admired the quality of construction of the I0JXX and its excellent performance on 144MHZ so I had a longer term plan to replace the Wimo with a 70cms version from I0JXX. Eventually I bought a 16 element from Aerials Parts of Colchester who supply I0JXX antennas in the UK. Progress was delayed by damage to my Achilles Tendon causing me a lot of pain when I tried to walk. Eventually I realised that there is  no antenna gain without some pain. 

At last I have managed to get the replacement done, no doubt at the cost of setting back my recovery from the ankle injury.

New I0JXX left, old Wimo right

Click to enlarge the images if needed. 

As can be seen from the photo above, this is really a maintenance job. Both antennas have 16 elements and both have 3m booms. They look that same from ground level, which is hardly surprising. I just wanted to install an antenna which did not twist in the strong winds we get here. The main difference is the feed arrangements. I am not setting out to improve on the claimed gain figures - they are identical.

If you do not live a short distance from cliffs overlooking the North Sea you might not need a stronger antenna like this. On the other hand the round anodised boom of the new antenna, plus the strong stainless steel fittings might appeal for use anywhere. Like the 2m antenna I already have, this new one uses a unique element fixing arrangement whereby the elements go through the boom and are fixed by plastic locking nuts either side. Also good for rigidity and strength.

Assembly instructions are clear. The instructions include the EZNEC+ plots and a set of suggested stacking distances.

EZNEC+ plots for 16JXX70 yagi

The parts included an Allen Key ("Hex Key") which you need to tighten the bolt holding the driven element to the boom. The snag with this was that the Allen Key was the wrong size. Not a problem as I have a wide range of Allen Keys available. That was the only issue with assembly.

On the Tennamast at GM4FVM - 16el 70cm top, 28el 23cm middle, 5el 4m yagis.

Obviously it is heavier than the rather flexible antenna it replaced. It was easy to build and install. On the day of installation was the NAC 432MHz contest and I worked 1 x SM and 2 x OZ. Next day was the RSGB UKAC 70cm FT8 contest and there I worked 4 x G, 2 x GM and 1 each GD and GI. Best DX so far (after two days) is to SE5R in JO58 at 862km. It seems to work. The SWR is 1:1.2 on 432.200MHz.

View with the mast lowered

This is basically a modernisation with an almost like-for-like replacement. I now have a more robust 70cms antenna and hopefully one which should last for years to come.

So far so good.

73 Jim

GM4FVM 

4 way sequencer from Hamradioparts

Do I need a fourth sequencer? No. However, the three I have are all based on the common approach of grounding the PTT line to the linear to change to transmit. Enter a Microset SR-500 144MHz linear amplifier which has an unusual way of activating transmit mode.

The PTT line from the SR500 comes out via a 3.5mm stereo socket, with a ground contact and a pair of wires which the manual explains cause the linear to go into PTT when connected together. However, grounding the lines just turns the linear off. All my existing sequencers use the standard grounding method for triggering the PTT and thus the Microset just turned off when it should be transmitting. So I needed a sequencer which is isolated from ground.

The need for a sequencer for the 2m set-up was explained on this blog back in 2021 here.  The basic diea is to turn off the preamp before activating the linear PTT, and do the reverse on returning to receive. The diagram from that posting is reproduced  below:-

Sequencing set-up for transmitting

Compared to the diagram, the problem with the SR500 is that the "Delayed PTT (grounded on TX)" is that the SR500 doesn't accept grounding of its PTT line. 

As the first step I decided to try to cobble something temporary up with my current Down East Microwave sequencers. This would have to allow for a PTT switching output isolated from ground. This did not seem practical from the PTT outputs themselves, so then I thought of using a relay. I bodged up a relay in the preamp supply and this worked. It worked, but it was a mess. As the relay was powered during receive I worried that it would overheat. As it happens the Microset has a very noisy set of fans so I turn it off when not in use. I wired the sequencer to the same supply. It and thus the relay is off when I am not using 2m and so heating of the relay is limited.

However, even though I used this lash-up for eight months it was not ideal. I did a lot of tests with the timing. My concern was that by feeding the relay from the preamp supply meant that the usual timing was reversed and the timing might be wrong causing either hot switching by the amplifier or causing damage to the preamp. Also this bodge only worked because I did not need a preamp supply as I was using my IC-9700 and it sequences the preamp supply itself. I would like to try using my IC-7100 for 2m, or at least have the option of using it.

The relay I was using was one from my parts box, and no doubt it is slow acting and liable to overheat if left energised. Perhaps I could source something better. Surely there was a better way to solve this problem.

I dithered about how to do this. I thought about building something from scratch but then I discovered that Hamradioparts make a sequencer board with isolated outputs. The details are here:-

 https://www.hamradioparts.eu/4-port-isolated-universal-sequencer-board?Product=606679942&Lng=en

 At €50 it is about half the price of the Down East ones I have been using and it has four isolated outputs which are all configurable for "normally open" or "normally closed" (in other words, useful for linear, preamp or fan use). Their non-isolated sequencers are even cheaper. The delay time is also adjustable. By comparison the Down East ones only have three outputs preset for purpose and the timing is also fixed. The big plus that made me decide to purchase the Down East ones was that they were solid state and therefore potentially faster acting and with no mechanical parts to wear out. Still, I thought this one would be worth a try for this specific purpose.

The ordering process was easy and the board arrived quickly. The instructions were clear and it took a short time to box it up with various sockets and LEDs coming from my parts box.

The boxed 4 port sequencer at GM4FVM

When the photo was taken I had not connected up the PTT line (yellow wires). After experimenting I connected it to the third relay which seems to give good timing between it and the preamp supply which was already connected to relay one. The four relays can be seen in the photo alongside their connector blocks which have both NO and NC connections. I fused it and added some LEDs to show that it is working.

So far it is working well. I did eventually put the lid on the box, whereas the old "temporary" relay system never got under cover (to allow for more cooling that old relay?) before I replaced it with this device. It seems very old tech compared with the solid state Down East ones, but it is cheaper and with more potential. The sound of four relays clicking in succession as I got to PTT is a bit odd, with four more when I go back to receive. Still, I don't have to switch it off to prevent against my old relay getting too hot. And I should be able to bring the IC-7100 into use with the Microset, even if just as a backup.

Hamradioparts also have an configurable amplifier controller which looks interesting but which is out of stock right as I write. 

So the question remains - why does the Microset SR500 not work with the standard PTT to ground system? I have had two other Microset amps and both of these used the standard system.

73 Jim

GM4FVM