On a very late season's noctilucent cloud observing session overnight, it was noticeable that a number of very fast Perseid meteors are already coming in, almost two weeks before the shower's peak.
Over the summer, I've been thinking about and exchanging e-mails with various people about 'metallic bursts' of signals at 50MHz. Superficially similar to meteor reflections, there are a few potential problems with this explanation.
Reflectors of radio, natural and man-made.
Firstly, some people definitely hear these bursts from European signals. Whilst I hear occasional meteors pings from Europe, I never hear the quality of bursts that I hear when listening transatlantic.
It may well be that this is a geometric effect, in that when I listen across the long distance of the Atlantic, I am 'looking' through a much larger volume of space, and thus have a greater chance of hearing meteor bursts.
But then, if this is the explanation, why do I not always hear such bursts when listening transatlantic? Why do I not hear these bursts, if they are meteor-induced, at all times of the year? Even without a discrete meteor shower, there are plenty of sporadic meteors to create paths if the 'longer path length' idea was correct.
I'm not trying to say that there is something spectacularly new to discover here. But there are parts of the story that make no sense at the moment. There are alternative explanations to meteor reflections as to why long distance signals might undergo the kind this kind of 'burst' propagation.
So, if you have any 50MHz capability over the coming three weeks or so, please do record any unusual periods of these 'metallic bursts'. If you do, please record the audio using your digimodes software, and not something like HRD; this is to provide time synchronisation so that the signals can be decoded later.
Well, tropo conditions were looking good this morning and, sure enough, D4VHF appeared at lunchtime, coming in with very strong signals.
Remarkably, this is the third 2-way QSO with D4 this year for me. Not bad going, considering the very modest equipment in operation - and the fact that the antenna was pointing a good 30 degrees west of D4!
Well, my endless question is: where do I go to spend an hour or two whilst my son goes skateboarding?
At least, when it's good weather for skateboarding, it's also good for radio!
IO73te, operating from dyke at extreme left.
So, off to IO73te, for some 10m work from a large bay. Even the tide was in today!
My antenna is, as usual, an elevated 1/4 wave vertical, this time made with some wire I haven't tried before - heavy duty stuff (but not with any core reinforcement) from SOTABEAMS.
At just £11 for 50m, this is much more acceptable for non-permanent antennas than the £50+ cost for the same amount of kevlar-reinforced wire, for example. It's actually good stuff, specially made to SOTABEAMS' specification, with a very strong PVC sheath and heavy stranded wire. Also good tangle resistance - an almost universally-overlooked feature of antenna wire.
Having set up on a windy sea defence dyke, built in the early 19th century by legendary engineer, Thomas Telford, I suddenly found that my DC supply wire from the battery to the banana plugs of the rig had started to melt badly!
Meltdown! Only use the best heavy duty DC supply wire, even at modest powers!
The wire is quite heavy duty stranded copper, but it is specified only for speaker wire duty. As well as being slightly too thin for the rig, even at powers never above ~40W, the insulation is probably also not of adequate specification for heavy duty DC use. Using only 10W for FT8, I split the twin wire to separate the conductors, in case it had melted through completely. This saw me through the next 90 minutes' operating.
This is really something to look out for if you are wiring from your car battery and hiding the wires under plastic covers inside the vehicle. There, you will never notice any melting until it's too late.
Anyway, I managed only one QSO on 10m, even though I was getting across to the US quite well. When I ran a short burst of WSPR at 1W, as well as being one of only about three UK stations being heard by N2HQI, I was stronger than the others two by a median +11.5dB.
A strong NW wind brings a taste of autumn to 28MHz WSPR listening at IO73tk.
UPDATE: Another visit to the north coast of Anglesey at IO73tk, yielded very good enhancements over my home delta loop, just ~2km inland, at 28MHz. The median difference was +12dB, with a maximum of +18dB enhancement over the home delta, and a minimum of +7dB.
It's been nice weather of the past few days, so an hour or two has been spent down at the coast. With virus restrictions much reduced in Wales now, we are all having to get used to the sudden influx of huge numbers of tourists, all of whom seem to believe that the virus has vanished.
I've had a chance to operate some FT8 using my 'go box', with an output not more than 15W and more typically about 8-10W into simple elevated quarter wave verticals. Previously, all of my truly portable work has been with tiny WSPR outputs, or SSB.
T-shirt weather at the coast (IO73vh)
It quickly became apparent that a choke is needed on a vertical used with a computer, especially when relatively close to the antenna, where coax lengths are similar to resonant radial lengths at higher HF (I was testing out 12 and 10m). Transmitting within about 2 metres of the antenna almost always led to the Raspberry Pi crashing, which it never does when no transmissions have taken place.
Moving to about 4 metres or so from the antenna base usually but not always eliminates the problem, but for future use, I will have to install a few turns of coax, or just a few wraps of coax around a split ferrite.
It's a moot point as to whether the Pi crashes due to common mode current along the coax, or the intensity of the field strength when next to the antenna, or both. Given that the crashing ceases with a fairly small increase in spacing, I suspect the main cause is simply the field strength at the antenna base.
A little more attractive. New interior, too!
Meanwhile, general aviation returns as a permitted activity this week, so radio takes a back seat for a while, whilst I throw a (newly refurbished) aircraft around the wet and windy skies of North Wales a bit!
A month or so ago, the shack's MyDel MP304 MKII linear PSU gave up in rather spectacular fashion, producing a brief humming noise, some smoke, and then - nothing. It's the first equipment failure of any kind I've ever had in many years' operating.
Buy with confidence.
I bought the unit from Radioworld, which I'm rather glad about, because they asked for the PSU - which was only about three months old, to be sent back to them (just £8, despite the unit's mass).
Back in action, thanks to the zero-fuss approach of Radioworld.
A couple of weeks later, and UPS delivered the PSU back to me in full working order! I'm not sure whether the unit will now last as long as my very well time-served SMPSUs, which have each seen thousands of hours' operation, but we'll see.
So, dear fellow operators, when you want the security of knowing you won't be fobbed-off if your equipment develops a fault, remember Radioworld!
I enjoyed reading the latest missive by Julian, OH8STN, about 'standard' power pole connectors and their potential problems.
I've never adopted the use of Anderson Power Poles. For one thing, they are very American in their nature. Americans seem to love anything that has a name attached to it, even if it's a dumb DC connector system.
Not just a connector, it's an Anderson Power Pole. Oooh!
The key thing that Julian gets to the heart of is the lack of any protection from accidental wrong connections being made. Power Poles offer no such protection, which really is a huge problem when out in the field - lack of time, cold, poor light, etc. Mistakes are then very easy to make.
Of course, when Julian speaks of 'standards', the reality is that Power Poles are no accepted standard at all. They are just something someone came up with, marketed, and were somehow adopted quite widely. There is no global industrial standard that everybody was consulted on and then agreed. Which is a good thing, because I don't think Power Poles are very good, or particularly affordable. Neither are they necessary.
The way I've got round these pitfalls is, for rig DC connections, simply to use heavy duty vehicle 'spade' connectors. Male is always one polarity, female the other. Try as you might, you can't connect them the wrong way, even in complete darkness. They are also perfectly happy in the rain for years on end - should you find yourself on portable operations a little longer than expected!
Pretty difficult to connect these up the wrong way. But they are easy and cheap to replace.
For solar panel connections, simply use a completely different type of connector. There are very many available - and that is the important point. By choosing your own foolproof connections system and sticking to it, you can pick and choose your own connector types from the plethora available, without being tied to one system like the Power Poles. You will also likely save money, not least because you won't be forced to buy things like battery packs that are only fitted with Power Pole sockets.
The amazing journey of the latest VE3KCL balloon continues!
The balloon, with its tiny 10mW transmitter, is currently only being received by KL7L. Yesterday, the balloon went silent for such a long period that it appeared to have fallen from the sky. This may have been due to entering into a longer period of true darkness at the balloon's current position.
But today, it's back on the WSPR screen, slowly making its way towards the Pacific coast of Russia.
Z81B. Do you know where that is? Well, I certainly didn't when it appeared on 12m, yesterday tea time!
Even when I looked it up in the RSGB prefix book, there was no apparent mention of it.
Eventually, having found it was from nowhere less remarkable than South Sudan, I knew which direction to point the 3-ele LFA.
About time we saw more activity from Africa.
Nice good signals both ways, and a new, rare country for the logbook. South Sudan is, of course, a war-ravaged country, and it's a real surprise to see any amateur radio activity from there. Small steps are, however, being made to bring peace to the country.
Conditions on the upper HF bands have been very good recently. So good, in fact, that I decided to throw together a 12m 1/4 vertical for coastal deployment.
I find the CSG Network site gives perfect results for wire lengths every time, but the matching is also assisted by downward-sloping radials from the elevated feedpoint. SWR in the deployed state is 1:1.
Radio with the family doesn't really work out, but when all you want to do is sit and drift off into the horizon at the coast, then it's fine. When I did take everything out, I forgot the coax in the process of transferring items from my RX bag to my transceiver box!
Take 2!
Last evening 12m was quite strong again, and the weather, though cloudy, very warm. I took an hour to deploy everything on the north coast, only a couple of minutes by car from home.
24MHz activity at IO73tk last evening, looking NNE.
With a new Raspberry Pi 4B installed recently, I found I hadn't set up all the variables in the software, so that took up a couple of minutes. But I soon settled down to some FT8, using 10-15W from the TS480SAT, powered by a small disabled person's scooter 12V gel battery that is good for maybe a couple of hours' work at typical FT8 transmission rates.
The 'go box', with in-built Raspberry Pi 4B.
Signals across the sea were, as expected, very strong and of the same kind of level I would expect using the 3-ele LFA from home (perhaps better, as I have high ground to the NE). The open vista to Sweden and Finland was particularly good for the signals, and Russia out to 4000km was also very good, with SNRs in solid, positive territory. I managed 11 QSOs altogether, just very casually operating.
And, so as not to break the tradition, a couple walking their dogs asked if I had caught anything. Arrrgghh! When they understood it was radio, they were concerned (jokingly) that "I might be talking to the Russians". Very funny. I replied that I am of Russian descent, and that if the couple wasn't careful, a Russian submarine would surface behind me. They left, feeling a little bit embarrassed at having shown their all-too-typical British prejudice...
After a spell circling the North Pole last week, the latest VE3KCL balloon and 14MHz WSPR transmitter is now floating around the extreme northern part of China and extreme east of Mongolia.
Receivers of VE3KCL overnight.
I managed to receive four spots overnight, three of which were -30dB SNR from the tiny 10mW transmitter, and one reaching -27dB at 03:08UT. Propagation predictions show this was a short path reception, whilst the UK was in the middle of the grey line period.
A nice late evening opening to the west coast US at 24MHz today - the first in quite a while from this QTH.
Early in the opening
I worked a few stations, which must have led to a cluster spot, prompting a number of other stations to appear on the PSKreporter map. Sadly, they were rather too late to catch the fading propagation; even at peak signals, I was using an ERP of over 1kW to make the QSOs.
A little later, localised Es enhancements gave extremely good signals in positive S/N territory to the midwest US, and -3dB to the west coast.
As is usually the case with 12m, point at the sun and make QSOs! Evening at home.
After five weeks without clear skies, I was finally allowed a window to the mesosphere early this morning.
I later found out that a man also lurking amongst the vegetation and mine spoil heaps of Parys Mountain was in fact a neighbouring radio (VHF specialist) operator, GW8IZR, who had helped me put my tower up back in 2013.
The intrepid VE3KCL balloon is still in the polar region, caught in a broadly clockwise circulation.
At the moment, the balloon is east of Franz Josef Land:
It looks like, at roughly the altitude of the balloon, that the circulation will either see it escape towards western Russia later today, or else get caught in westerly flow again that should see it get even closer to the North Pole than it did yesterday.
Even if it does escape the the south today, it seems it is likely, a day or so later, to get caught in a northerly flow that might take it straight back to the pole again!
Time will tell. Nice also to use this opportunity to check the performance of 14MHz reception, where I ended up at number 5 in the global rankings, but actually a joint 4th, just that WA2TP had no errlog:
Another VE3KCL balloon is floating around today, last heard from JR55 grid (see update), which is so far north, at slightly over 85 degrees, that it is a very narrow rectangle, not a square (as projected).
Update: A little later, the balloon was received here from IR07, which is only between 335km and 225km from the geographic pole -a comfortable beating of my previous record. Assuming a height for the balloon of 30,000 feet (9.144km), the north pole itself is in fact visible from even the most southerly limit of IR07 (the horizon being 374km distant from this height).
Happy to be one of a small number hearing the balloon at 10-10:30UT.
I was curious to see how much more strongly the balloon would be received at the coast, so my son and I went off to the north coast of Anglesey and set up the trusty 1/4 wave vertical, just ahead of some heavy rain.
Listening 14MHz WSPR at IO73rj, looking north.
We managed two spots from the balloon, with large signal enhancements, relative to the delta loop at home. First, here's the signal at the coast (I had no time to change the callsign or locator due to weather):
And, second, the delta loop (12:58UT here really is that time, not an hour incorrectly set; the 13:58UT spot heard at the coast was not detected at home, indicating a ~20dB enhancement if we take the limit of detection as -34dB), remembering that the delta is 2-3dB inherently better than the vertical:
So, the 14:08UT spot at the coast was ~16dB stronger on a like-for-like, vertical-by-vertical basis - a power factor of 40 times, with an indication of maybe a bit more available, had we more time to assess.
Here's the plot of VE3KCL at 14MHz being received at home (not the seaside) in IO73tj (vertical delta loop, SDRPlay RSP1a):
If you are in Wales and are thinking of applying for planning consent for antennas (or anything else), you would appear to have just a few days or weeks to avoid a substantial increase in the fee.
This is from a letter to all local authorities issued by the Welsh Government this morning:
The other way of approaching planning as the moment is that these departments are so poorly resourced in both monetary and staff terms, that now is a good time to not apply for consent and qualify for lawfulness under 'the four year rule' if - and I stress the if - your local conditions mean that a complaint from the neighbourhood is already fairly low.
Remember, though, that four years is a very long time to hope nobody sends you an enforcement notice. But if you make it, your antennas become immune from enforcement. It is not, of itself, unlawful to erect a structure without consent. But, obviously, failing to comply with an enforcement notice as a result of doing so, is.
If, after that point, someone complains, you do not need to apply for a Certificate of Lawfulness, but you can if you want to; it has really very little merit, despite many Council's tendencies to claim you might have trouble selling your house without such a certificate. This is really just pique at being powerless to do anything. If someone buying your house actually wants the antennas (unlikely), then it's much cheaper and less hassle just to buy an indemnity from your solicitor, costing about £50 as a one-off fee.
The other piece of advice always worth keeping in mind is that, if you claim lawfulness by expiry of time limits or by being granted consent, then make sure you apply for the tower and antenna separately, not together. That is advice from a former planning inspector, and ensures that, if you remove an antenna and change it for another one, you do not run the risk of someone saying you need entirely new consent for the new antenna placed on the same tower. It's a subtle difference, but an important one.
No sooner did I think I had seen the last of idiotic people from the 50MHz community than I received a reply from another one.
Noctilucent clouds. Apparently, if you have personally never seen them, they don't actually exist for anyone!
In this email, the dear operator wasn't initially entirely dismissive of 'these clouds of [mine]'. Clouds of mine? Hmmm. Sounds familiar.
He then proceeded to tell me how people got "very excited" on chat rooms about the appearance of NLC, because they believed there may be a link between them and propagation at 50MHz.
"Yet, I have gone out to look and seen nothing?"
That inclusion of an incongruous question mark is very social media-esque. It's a different way of saying "If these clouds really exist, how comeI haven't seen any?" The 'I' is more important than anything else, in other words.
The man later revealed he had higher ground to his, erm, north and north east - precisely the area that NLC are normally seen, typically at low elevations!
I patiently referred the gentleman in question to various databases and scientific papers spanning decades, should he wish to see proper evidence for the existence of NLC, seeing as, he claimed, the weather was always too poor for him to check for himself.
Well, the weather has certainly been poor this year. But I'm not quite sure what this man's been doing in other years. Probably looking up into the sky whilst it was still full daylight, I guess...
A little 14MHz WSPR monitoring overnight shows that VK3QN, fixed on a long path, 130 degree beam heading from Australia, is now peaking roughly 20 minutes earlier than it did around midsummer, just over two weeks ago. Quite a sensitive indicator of the year's progression.
14MHz reception of 5W WSPR signal from VK3QN, 2020 July 07-08.
VK3QN 14MHz fixed long path array. Image (C) VK3MO, with permission.
Sorry if you've just arrived here from the blog of PE4BAS, but his superb recording of 50MHz bursts, which are certainly not aircraft scatter, and possibly not meteor scatter either, is really worth listening to.
So far, I am only hearing these precise type of bursts on long DX paths, in my case, to the US, and in Bas' case, on a path to JA. G4RRA also find these bursts on longer DX paths, and thinks they are meteor scatter. Perhaps the longer path simply gives a greater likelihood of such scatter, perhaps even combining to give multi-hop?
I'm not sure how we disentangle one thing from the other, except to see if the effect on DX paths increases during the upcoming Perseids (around August 12), by which time PMSE and Es will be far less common as we reach the end of the summer season.
Bas' poetic description of waves lapping at the antenna is very nice:
A diversion today, with construction of a simple hydrophone, to see if we can hear the sounds of our resident pod of Harbour Porpoises.
This is very easy to make, using a cheap and readily-available piezo speaker, which you can buy from Ebay or recycle from those musical greetings cards; both are remarkably sensitive.
All you need to do is glue the piezo sounder to the face of some plastic (I used perspex, 3mm thick), place an 'O' ring seal around it, and bolt the top plastic to this. Don't overtighten. In fact, I recommend you use brass or copper plate, rather than plastic, as plastic is prone to cracking.
Sealing the hydrophone. The gap between the perspex edges was later sealed with silicone as a first-layer barrier. I also added silicone under the bolts. But the O ring probably is enough on its own.
To pass the wire to the outside world, I cut a small 'nick' in the 'O' ring and added plenty of silicone sealant to restore the seal as the bolts clamp the housing shut - you can see this in the photo.
UPDATE: The perspex, somewhat predictably, is a little too fragile, and tends to crack. My second version is two food can end pieces, one from the top, one from the bottom (they will tend to give sizes slightly different, that fit, one inside the other. A small nick to allow the cable out, and sealed between plates with plenty of silicone, makes a much simpler, cheaper and robust microphone housing.
Piezo mic is between the two can lids. You can varnish or paint this (front) side to protect from corrosion.
I further siliconed the mic assembly to an old perforated aluminium backing, onto which I can attach weights and a rope for deployment.
Reverse of the mic assembly, silicone coming through the holes to provide secure attachment (I also soldered copper hanging hook to the mic assembly before I inserted the mic (obviously!))
No interesting recordings beyond the kitchen sink yet (it's raining with a 90km/h wind again), but the hydrophone works well and has very low noise. It's simply connected to a cheap handheld office sound recorder, the input to which can be monitored using some headphones.
Great fun! Costs were: perspex £3, piezo (5 pack) £3.95, bolts, cable, audio jack about £3. A resonable quality commercial version is a minimum of £60.
The past week has been interesting, challenging and, to some degree, despairing.
Interesting, because I've had a lot of fascinating discussions with the top scientists in the field of atmospheric science.
Challenging, because this field of endeavour attempts to study a region that is 85km up, inaccessible to all but sounding rockets.
And despairing, because I have really seen the worst of the amateur radio community. Luckily, I also saw the best.
The discussions were about the potential for PMSE to play some part in 50MHz radio propagation. Being science, one professor was sure PMSE has no role, whilst another said he "would not be surprised" if they did provide long-distance propagation - providing many reasons why that could be.
None of this, of course, is the same as saying that PMSE do, as a fact, assist DX radio propagation. Nothing is settled, but there is reason behind wondering about this. This is a subtlety that escapes some of the 'big gun' 50MHz operators I've had the distinct misfortune to come into contact with this week.
PMSE seen over mid-Wales by 46.5MHz radar.
Some of these 'big guns' behaved very predictably in not responding at all to enquiries about their beam headings during Europe-JA openings at 50MHz. Sadly, one of them is Welsh. I suppose their egos are so big that anybody asking a question is a 'weakling' that doesn't know something - unlike them, who know everything.
Indeed, I was rather amused to read the response of one person, who has a vast collection of VHF antennas stuffed into a small area such that he must never have heard of adverse antenna interaction. I suppose the drive to be the biggest and best is just too much of a draw for some.
This man - I'll spare him the embarrassment of identification - did at least respond. Some of his response could be taken to be rational. But much of it wasn't. Having admitted he had never heard of PMSE before, and that was only "what YOU" call it (?), he then proceeded to very confidently - but very wrongly - decide PMSE was what radio people call "Aurora-Es".
Nope.
And, apparently, only "some researchers" call PMSE, erm, PMSE. He didn't enlighten me as to what the 'other researchers' call 'it'. Again, ?
In a second response, my dear correspondent was "sure" he'd "seen a paper somewhere" (haven't they all?) that showed PMSE only occur due to aurora, and that my information to him about how they actually occur - accepted in broad detail by all scientists - was a load of rubbish.
The underlying physics that leads to PMSE is pretty well understood, and aurora has no primary role in their formation. A very recent study by the South African Antarctic programme showed that aurora (high geomagnetic activity) suppresses PMSE formation. Not very surprising, given that these energetic events will warm things up, not cool them down.
PMSE plotted on a restricted height scale. Image: MAARSY.
I never did receive the reference he claimed to have seen, nor any explanation of why someone so involved in 50MHz had never heard of PMSE, regardless of whether or not it is involved in radio propagation.
It was clear that this man simply wanted to dismiss absolutely anything that anyone else had to say as nonsense, regardless of how ignorant he was - and admitted to being - and how self-evidently accomplished, yet at the same time careful in their conclusions the atmospheric scientists and their support staff are.
It really is very sad. I had a think about what motivates people like this. In the end, they are idiots who can't accept their very significant limitations but who feel that typing rubbish neatly out on a screen lessens their stupidity. The vast money spent on chasing their dream of being the biggest and best in the 50MHz world makes them omnipotent, apparently. No need to work for a degree, a Ph.D, and a professorship. Just stick an antenna up, buy an amplifier and rule the world! I suppose building up your reality in this way must be very difficult to let go of and, evidently, it is.
And the best side of radio? The responses from Bas, PE4BAS, about his experiences at 50MHz. Others were equally lovely, including Jim Bacon, G3YLA - a professional meteorologist who once graced our TV screens. And Tim Kirby, GW4VXE. Nice, open-minded discussions, with questions, critical and supportive back and forth, and some useful data that helps us all - not just me - wonder about PMSE and any role they may have. A big thanks to all of them. The others? Well...
To relax from all this, why not enjoy some classic Echo and the Bunnymen: 'When You're Strange':
Well, it's been a windy, wet few days, but it started to look a little better this morning.
So, instead of our usual walk around a local lake, we decided to take the 14MHz WSPR receive kit along with us.
Cefni reservoir, central Anglesey, taken when I went up in a helicopter a couple of years ago. Huge cyanobacterial bloom due to a very shallow, highly fertiliser-polluted lake. Operating was from lower right, near the dam.
It took about a minute before someone told me I wasn't supposed to be fishing from the shore at the moment. I get this all the time, coast or lake. I should really have a sign, saying 'I'm not bloody fishing!' on it, to save my effort of explaining!
Anyway, I was interested to see if the freshwater would bring benefits. I thought the much clearer boundary between what is water and what is dry land might give a sharper difference in the signals assisted by water to the west, and those not, from the east.
For comparison, I ran my identical 1/4 wave vertical at home at the same time.
At the lake. Foam in the water is from a decaying cyanobacterial bloom.
I couldn't stay more than about 40 minutes, and there were only four stations coming in from the US at the time, thanks to very strong D layer formation.
But this was enough to show that the signals over the water - it is only a small reservoir - were up to 10dB stronger than those being heard at home. There was one case - AJ8S/1, where the lake signal was -14dB, but was not heard at all from home. That might signify an even stronger enhancement by the water, but we can't quite be sure by how much.
Beautifully, all the signals from the east showed only a median 0.25dB better signal from the lakeside, which is near enough to zero, and shows that the cut-off at the lake is, as I expected, very much sharper than that seen at the seaside, where there are large areas of seawater-saturated sand all around the antenna, giving good enhancements from all directions.
This result also confirms the noise assessment I made a few weeks ago, which was a difference of only about 1dB less noise at the seaside.
So, to summarise, lakeside = +8.5dB to the west, compared with my home antenna, and ~0dB to the east.
A few days ago, I wrote about the very strange-sounding signals heard at 50MHz, which I've never heard before, and only in the direction of the USA.
Superficially, some of the signals seem to be meteor scatter, and one or two people have argued very emphatically - usually based on a peceived 'long career' on 6m, that this is all the signals are.
But the question is: why is this supposed meteor scatter not present at other times? And for that, there is no answer.
I can imagine someone saying that it's meteor scatter plus Es, so that meteor scatter happening very far away is then bouncing off Es clouds. I think that would ridiculous, all things considered.
I heard this strange effect again yesterday (01/07/20). I could again confirm that all the signals affected by the peculiar propagation were from the US. It really does sound a little like meteor scatter, but again, why only when there is Es propagation to the US? 30-37s and 56s onwards are where you can hear the strongest effect:
I'm open to other explanations, but for the moment, I think it has to be very shallow, transient reflections from locally electron-dense regions of the E layer. Moderated 'Comments' is now open again for any ideas you may have...
