Long distance 23cm aircraft scatter

The result: 590km QSO on 23 cms.

The recipe: IC-9700, 150W, 28el yagi with 1.5m boom, Airscout.

Once again, when I started on 1296MHz I would never have believed this was possible. A 590km microwave contact on a flat band with an antenna just 1.5m long? No chance. And before I started on 1296MHz I doubted if I would work anyone, even in my own square. On 21 August I worked a new one four squares down and three across.

I am pretty sure that this is my longest aircraft scatter contact on 23cm. Sure, I can get further during tropo lifts, but conditions were normal that day. To make things harder, my normal 36 element 3-metre boom antenna has been dismantled while I deal with corrosion damage. So I had gone back to the 28 element WIMO given to me by Neil G4DBN - my first ever 23cm antenna.

The WIMO 28 element antenna between 70cm and 4m yagis at GM4FVM

Click to enlarge images if necessary. 

Frankly, I was not confident about reverting to the WIMO antenna. The antenna has 20 elements along the boom and eight a right-angles to the boom as a reflector. It works OK, but being half the boom length of the 36 element brings a 2dB reduction in gain, despite the reflector. However, in the 23cm UKAC on 19 August I worked six stations and that restored my faith in it to some extent.

At 11:17 on 19 August I saw EI3KD calling on 70cm FT8. My beams were still pointing in that direction as I had earlier worked EI4ACB. EI3KD and I then worked on 70cm. Mark sent a message on Tx5 that he was going to 23cm. I followed up to 23cm and I could see strong traces of Mark's signal via aircraft scatter but the Doppler shift was too strong to decode the signal on FT8. I contacted Mark via KST Chat and said that I would like to try Q65 but at that stage I did not have the time to try. I did say though that I would like to try when we had time.  

And so it was on 21 August that I saw Mark again on the Microwave section of KST Chat and I asked him if we could try Q65. I think I blundered slightly by suggesting Q65-30C as the whole thing  might have gone better on a 15 second period. Anyway, off we went and within 30 seconds of calling EI3KD I decoded Mark calling me.

I was pretty sure that we could complete because of the path as shown on Airscout. There are plenty of planes passing over the Irish Sea along the path of our contact. The problem is that not many are at the right point along the path, shown by the short pink section in Airscout.

Screenshot of Airscout along the GM4FVM/EI3KD path on 24 August 2025

Only the mid section of the path west of the Isle on Man can be useful for reflections. On the screenshot above (taken today) I can easily 19 planes have just crossed or will cross the path, but only one is heading for the pink section and likely to provide us with the reflections we need. So this might take some time and need a few planes.

As Aircraft Scatter paths get longer, the pink part of the path gets shorter, plus other obstructions such as hills get in the way.

Screenshot of Airscout along the GM4FVM/EI3KD path on 24 August 2025

Airscout also shows this, and the vertical diagram above shows the small pink area which planes will have to be in to help. The vertical scale is the altitude of the plane. Anything landing in Ronaldsway airport in the Isle of Man is not going to be high enough! The bottom diagram above shows obstructions on the ground along the path (on a different vertical scale!), with the Irish Sea a long gap in the middle, but the Wicklow Hills and the Pennines at each end.

Another problem is going to be Doppler shift created by the movement of the aircraft across the signal path. Doppler effects rise as the frequency goes up. Quite a few 2m and 70cm contacts on FT8 are put down to Tropo propagation when in fact they are assisted by aircraft scatter. However, the Doppler is often too strong to allow FT8 to work at 23cm. Q65 is ideal in these circumstances as it compensates well for Doppler. I did increase "Max Drift"to 30. Exactly what the "Max Drift" setting does I have no idea as the WSJT-X Guide has not yet been updated to cover it. Suffice to say that in a previous aircraft scatter test it seemed to help so I increased it again this time.

Net result of all this - only a few planes at the right height would complete the contact and Q65 will need to cope with the Doppler.

Long pause after the first decode

Airscout produced hope with small planes and possibles which altered course. Lots of hope but no results. But then, after 19 minutes two planes in opposite directions were due to pass over the right area almost together. Result:-

Aircraft scatter QSO complete - even to the 73s.

The best decode at my end was -13dB which did look rather faint and Doppler shifted. The 73 afterwards was very difficult to see, but Q65 decoded it OK:-

Final decodes in Q65

So although nearly 600km is almost right at the end of the radius of aircraft scatter QSOs, it did prove practical even with a less that brilliant set-up. I now have 41 squares worked on 23cm. Who would have thought it?

Even if you find all this daunting I would still urge anyone to try 23cm aircraft scatter. There are lots of IC-9700s out that which, like mine initially, have never strayed on to 23cm DX. All you need is a decent antenna and coax. Or, in my case, a simple antenna and some coax I used to use on 432MHz. It is perfectly possible to make good aircraft scatter SSB QSOs during the contests using simple equipment. At other times many QSOs are arranged using KST microwave chat. Airscout helps, but you can just rely on the DX stations to tell you when a plane is approaching the path. Let them use Airscout!

Nothing here implies any greatness from GM4FVM or his equipment, which was largely donated by others. GM4JJJ (sadly SK), G4DBN, and G8SFA each helped me no end. Most local amateurs will help if you ask. 

There is still more for me to do on 23cm. It is not the weird place I used to think it was.

Perhaps later I will explain a bit more about Airscout. 

73 Jim

GM4FVM 

FT8 etc, weak audio, try unticking audio enhancements in Windows

A fellow ham was having problems with the audio stream on data modes after he switched to a new Windows 11 laptop. It emerged eventually that a box marked "Enable audio enhancements" was checked and this was altering (mostly reducing) his audio level. He uses WSJT-X but I expect that the same thing would apply to MSHV and all the rest of digital radio software.

This was in Windows 11 but it may apply to earlier versions of Windows too. 

In the end what we needed to do was untick the box, but finding it was a long operation.

Untick this box in the Advanced section of the Microphone Properties tab

What are Audio Enhancements? 

Audio enhancements depend on the hardware installed or connected to your PC. Therefore, on my basic gaming computers and laptop they were absent. I found this on a Windows help site :- 

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

Audio enhancement packages are designed to enhance your specific audio hardware performance and quality.

Available audio enhancements will vary depending on the manufacturer.

Sometimes these audio enhancements can cause problems with audio and sound. If you encounter an audio or sound problem, you can try disabling audio enhancements to see if it may solve the problem. 

================================== 

So the basic answer is that these enhancements could be anything, and they could alter the audio between your rig and your WSJT-X software in any way you can think of, and probably in some ways you cannot imagine.

The solution is to find the rig's entry in the Microphone Properties tab and turn them off. 

The problem here was variable and often very low level audio stream. Solving it turned out to be tricky as I had no idea what I was looking for. My laptop does not have this box so I was at a loss. I took my IC-7300 and my laptop over and compared it with the other setup. His rig worked perfectly with my computer, my rig worked perfectly with his old computer, my rig showed the same problem as his with his new computer. Clearly the problem was in his laptop.

After a lot of pondering, we went through the Sound settings (you find them in Control Panel). Mysteriously, Windows calls the audio input section "Recording" so click that (the output is called "Playback"). Then you click the tab for your rig input, probably "Audio Codec" or "Audio Device". Microphone Properties appears and you click "Advanced".

Untick the "Enable audio enhancements" box

If you are wondering why my example says "Headset Properties" at the top, I just used this illustration to show where the culprit lies. My PCs do not normally show this box and therefore I was totally unaware of its existence. However, I found that by linking my JBL headset, which has a microphone, to the computer via Bluetooth, I could make the box appear. That is why the audio stream is only tape recorder quality; for radio purposes I use DVD quality at 48000 Hz.

So if your existing PC does not have this box you can ignore all this completely. But if you buy a new machine or something is updated or added, you might find that it suddenly appears. And your audio stream level could suddenly take a huge dive.

In any case, I do not like pre-ticked boxes in any circumstances. Windows updates have a habit of including new pre-ticked boxes for features I never requested and don't want. This is just another one. 

If a pre-ticked box suddenly signs me up to a credit agreement I never asked for I could probably live with the annoyance. But when pre-ticked boxes affect the audio stream for FT8, well that is just outrageous.

This should be made illegal and the perpetrators locked up.

Or something. 

73 Jim

GM4FVM

What to do at the end of the current solar cycle - 432MHz?

What, is it over? Well, no, but I have been thinking about what to do when it is. The answer appears to be that I should "do more of the things that I like doing". Such as ... working a ton of stuff on 432MHz.

I suspect that an HF operator might go lower in frequency bands, and I will probably go higher. No great breakthrough involved in that idea, but it would involve readjusting the direction of my efforts and maybe some equipment.

For a couple of weeks I have been dithering about what to do when (if?) the intercontinental DX fades away. Should I switch my emphasis away from 6m and 4m? To what ends? Go back to more EME (moonbounce)? What result am I striving for? What will I end up enjoying most?

And then, without bidding, up popped a tropo opening on 70cm. Wow! I was aware of a high pressure system approaching, but it did not look as if the timing was right for the two 70cm contests in August. The first contest is the RSGB UKAC on 12 August using SSB and CW and I do not often participate in that one. Usually I turn my beam East on the same evening and give away points in the Nordic contest going on at the same time. I usually do quite well across the North Sea, and I work a few stations quite easily. The second contest on 13 August is the 70cm FT8 UKAC.

On 12 August I managed to work PA3CWS at 08:36 but nothing further until DK6JU at 16:02 and DR0X at 17:25. DR0X was a huge signal calling CQ for quite a time but he got very few contacts, which indicated a duct forming over the North Sea. Once the contest started could only I allocate it about 45 minutes due to domestic duties. Between 19:15 and  19:57 I contacted 4 x PA, 4 x OZ and GM8JBJ. Total for the day was 12, not bad for a 70cm operating session.

13 August dawned bright with haze over the North Sea. The air was still and with high pressure it all looked great. Sadly I was to be out of the house for most of the day. Between 06:26 and 08:48 I worked 6 x PA, 4 x DL plus OZ1DGN,  F5APQ and G4RQI - a good two hour spell. I was then QRT until 17:56. After that I was busy and could just look in for five minutes at a time. In a series of five separate five minutes spells, 6 x PA, 3 x GM, 5 x OZ, plus DL5EBS, EI3KD and LA6P 

This contest work plus a few worked later produced this result:-

432MHz contacts at GM4FVM on 12 and 13 August 2025

Total operating time was probably around 4 hours but this is hard to judge given that I was in and out of the shack. It brought a total of 38 QSOs in 8 DXCC including 16 squares. Best DX was to DG0KW in JO64 at 978km, there were nine QSOs over 700km, and nearly all the rest were between 600 and 700km. 

After this I went on to 50MHz and worked PY5EW in GG46 at 9940km.

Now this made things very plain to me. I was much happier reaching 38 stations on 70cm than I was working the the far more distant one on 6m. Whether this PY contact will be possible outside this sunspot peak I am not sure because I worked PYs at the bottom of the cycle too (but not that far away). But if 6m DX declines I can still enjoy a blast on 70cm.

I also get some pleasure by doing things like this without a kilowatt linear and a vast stacked array of antennas. Just 150W and 16 elements - modest by 70cm standards. 

Everybody will have their own place to go when the DX declines. Top band? Construction projects? Building ships in bottles? Anyway, for me, a good blast on the higher bands when conditions are good is hard to beat.

Conclusion: do what you enjoy and don't fret over what the sunspot cycle has given and then taken away. 

I will now reflect on the fact that outside a contest I often struggle to work anyone on 70cm. Lack of activity is a big problem, and also the narrow antenna beamwidths can make life difficult. But being very busy during a contest brings its own joy so I think I will migrate back up the spectrum when there are poorer harvests on the lower bands. 

 73 Jim 

 GM4FVM

VHF propagation changes like the weather

I think of the Solar Cycle as being like the annual climate chart, changing over a longer period of 11 years, but vaguely predictable in the long term. VHF propagation is more like the weather, seemingly changing at random week by week and day by day. Here in IO85, also like weather, VHF propagation can change minute by minute. (I will avoid the Doobie Brothers reference which would have been Minute by Minute - I keep holding on).

The 11 years Solar Cycle may bring F-layer propagation, increase TEP, or decrease aurora as it passes along, but its influence over Sporadic E is debatable. In fact, what causes Es to vary like the weather is a mystery. Take the last two weeks. Two weeks ago on 70MHz I managed eight QSOs, not much to report for a seven day period in late July. Of course I blamed everything from my station to some of the more kooky theories about Es. Eight QSOs to seven squares in five DXCC in a week. Best DX was not bad at 1859km to EA6SX but for this time of year those were slim pickings.

I was comforted by the old saying "what goes around comes around". According to this, things balance out in the end. A more scientific approach might be the statistical concept of "reversion to the mean" which states that if things are unusual then they usually go back to normal soon. So maybe next week would produce a bumper catch of stations to compensate for a thin netting the week before. What are the chances of that happening?

"Patience dear boy" as someone might have said. Me? Patience?

Last week the next seven days duly delivered. It reverted to the mean. I had 59 QSOs to 15 DXCC in 43 squares. Even the DX was better - EA4L at 2122km. 

WEEK ONE - 70MHz contacts at GM4FVM - 22 to 28 July 2025

WEEK TWO - 70MHz contacts at GM4FVM - 29 July to 4 August 2025

As usual, click on the images to enlarge them if necessary

So one week's Es is different from another. What does this prove? Well, whatever the figures say for me it is mostly about things which are all in the mind. as well as the propagation. There are lots of random factors at play with things like this. For example, was I at home, in the shack, waiting for a contact when an opening occurred. Was there anybody else at the other end in a similar state of readiness. Were we both likely to use the same mode? What about the time difference (like me doing my post-22:00 round up when it is after midnight in Finland)? Was there an opening to the West where only the cold grey Atlantic lies to swallow up my radio signal?

The thing is, after the first poor week I might be tempted to give up. I might think that 14MHz or digital voice could certainly be easier (perish those thoughts). Perhaps it is all in the mind, but that first week could have put me right off trying again.

Things got better later. With such a random set of factors set against a pretty chaotic propagation background, OF COURSE there will be weeks when less happens. There will also be weeks when lots of things happen. I have to take the rough with the smooth.

The sunspot numbers change, the weather changes and tropo propagation comes and goes just as Es does. It helps to have several bands to use.  I worked V51WW on what was probably Es-linked 6m TEP. Also, two PY stations probably on multi-hop Es. 

Things often get better if you keep trying. They would get better anyway whether you try or not, but if you are still trying at least you will be there to witness it.

73 Jim

GM4FVM

Scotland to China opening on 50MHz

Did I get this wrong? In my last post I suggested:-

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

"... maybe not!" And so it proved.

On 30 July I could see that some stations south of me were working into Japan though there was nothing from Japan heard here. I reckoned that something might happen so I beamed at about 30 degrees and started calling CQ. I worked OH5KNL, SM0GNS and OH1EEZ, all in the right direction. It seems to be the case that Es towards the Nordic region is necessary for propagation to opening towards East Asia.

Then I was called by BG3OJZ at 08:48 and completed that contact. This was followed by working three more stations in China, including BA4SI at +01dB. Shortly afterwards BA4SI peaked at +06dB. I topped it off by working JE6WOQ at +00 at 09:16. I also called but did not complete with two more stations in China and two in Japan.

50MHz contacts over 7900km at GM4FVM on 30 July 2025

The distance increased at the start of the opening from 7963 to 8423 and then 8928km. The propagation then shifted slightly to the East at 8382 and finally 9096km. Not bad dx for me.

Someone suggested that I should explain why this happened so late in the year when this type of propagation is usually associated with the end of June equinox. I have no idea about why this happened.

I heard at least six other GM stations take part in this event, plus two GIs. This suggests that there is nothing special about my station or my location.  

Despite several failed attempts I had only contacted one station on 6m in China before, and that was BA4SI on 27 June 2024. The problem with this later opening is that I cannot lower my vigilance as July comes to an end. If this can happen at the end of July, then can any propagation happen at any time?

73 Jim

GM4FVM

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

Nice opening GM to Japan on 6m

Most years around the summer solstice there are unpredictable morning openings to Japan from here on 50MHz. I say "most years" and "around the solstice" but the whole thing is pretty unpredictable. So too are the operations I have to engage in to actually work anybody. Stations rise above the noise and often disappear within 60 seconds, requiring some pretty sharp reactions (which I don't have any more). As for around the solstice - I have worked this path as early as 2 June and as late as 23 July.

50MHz contacts at GM4FVM on 23 June 2025

As usual click to enlarge images if you wish. I am pleased to see that "Project Logview" has appeared to fill the gap left by the Log Analyser by Mario DL4MFM. My data analysis comes from HamStats by VA2NW. I will try to cover all this in a posting soon.

After listening and calling for quite a few days, there was finally just such an opening on 23 June. Between 08:31 and 09:03 I worked seven JAs in five squares. I also answered a call from OH6KXL. It is this contact with OH which shows the path these contacts follow. There has to be a Sporadic E opening to OH or thereabouts for me to link into the path which crosses close to the North Pole. 

Best DX was JR3REX in PM74 at 9158km. I only heard stations in Japan unlike at other openings where stations from Korea and China have sometimes appeared here. I tried and failed to work a station in Asiatic Russia at around the same time. This time signals were quite strong and I completed about 50% of contacts, which is much better than previous openings.

The two new squares I worked bring my all-time total for Japan on 6m to 19 squares. It has taken me six summers to do this via 50 QSOs, though I have only managed to reach Japan in four of those years. Realistically I have about five squares left to target in Japan, leaving out watery squares. I do not view it like that though, working 9000km to Japan on VHF remains great fun for me so new squares are pretty incidental.

When this path was initially discovered it was speculated that it might be a new type of propagation. More recently it has been suggested that it is just a special version of multi-hop Sporadic E. My own opinion is that it is multi-hop Es, however unlikely that seems in terms of the number of hops involved. 

Whatever - when it happens I really enjoy exploiting it. OK, most days it does not happen, and when it does I have to scrabble to make contacts. During one QSO seven JAs called me, none of which resulted in a completed contact. However, working 9000km on VHF? What is not to like? 

73 Jim

GM4FVM

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