Monday, 21 September 2015

Farewell to the Flex 1500

I cannot fault the Flex 1500, it did exactly what it was supposed to do. After almost 4 years use, I have changed the way I do things here, so we have parted company. However, not because of any fault on its part.

For the first three years I used it as a transverter driver. Once it had sorted itself out it did that job very well. It can produce 0dBm, (1mW), and it has all the necessary sockets needed to drive a transverter with separate tx/rx feeds, which is the best way to do it. Then about a year ago I stopped using the transverter and at that point the Flex became less useful.

I used it later on HF as  5 watt rig, and via a linear, but once I did not need the low power outputs it no longer formed an essential part of the shack.

To start with it caused almost total confusion. The early versions of the PowerSDR software simply did not work well. After about six months ownership, Flex got together a series of updates, and then bundled firmware updates along with them. This eventually sorted it out, and after that it worked perfectly.

There were some surprises at the start. I had thought that my Pentium computer would drive it - not a chance. So I had dodgy software and a computer which was too slow, so almost nothing worked. I upgraded the PC by building one with an i5 core and it was perfectly happy with that, and then later used a 4 core AMD chip based PC. Nae bother. After that, few surprises. The display on computer is fabulous, offering band scope, outgoing modulation, phase, ... pretty well everything is adjustable, ... power output of 5 watts is achievable and the thing is stable.

So it is a 5W output HF rig covering all amateur bands from 160 to 6m, or at least all the bands in its "turfed" area. So mine was turfed for the UK. After the UK got 60m, I had it re-turfed to "UKplus", which covered 60m, all of 40m etc. Unless you had a very early one (I did), they all came with UKplus anyway. Then you have the transverter output for QRP - and I did run 1mW from there and worked 4X that way. It connects to the PC via USB, which is a little bit of a snag. The USB connection is a bit low speed and I did have a bit of latency on CW - but I do not use CW much! I am told that you just turn off the break in and use an outboard buzzer to listen to your CW. Or I sent CW from the keyboard.

It worked very well on WSPR and other data modes. As is often the case with SDR radios, you have to set up virtual data and audio cables to run data, and I have explained this on other postings. It was nice to hear from several amateurs who followed my approach and got their Flex rigs to work on data.

Here is an example of me using the Flex panoramic display to show something I could not even hear. My Wouxun 699 handheld seemed to be transmitting for a period after I let go of the PTT. I listened on other receivers but could hear nothing. Using the Flex and the trasnverter I could actually see the sub-audible modulation on the display ...

The rogue transmission is the very narrow trace before the wide click of the transmission ending. Eventually I found a way of turning this off (it was some sort of signalling pulse for commercial use) and check with the Flex that it had stopped. And I have used it for dozens of similar tasks like monitoring my signal, looking for frequency standards, checking frequency stability etc.

So as you might guess, I am sorry to let it go. However, that is the way the FVM shack works. Several cheaper rigs, regularly updated. I do not wish to be tied to a modern day boat anchor.

I hope whoever ends up with my old Flex 1500 enjoys using it. After those first few months, I certainly enjoyed it.

Now, what is next?


Tuesday, 15 September 2015

Anytone AT-588 - new 70MHz FM rig and antenna

I have not managed to work any 70MHz (4 metre band) FM DX this year.

This is disappointing. The plan was that my 4m vertical, a Sirio J-pole, would go on top of my 6m HB9CV. But when I stood up there trying to locate the pole with the beam and the hefty 4m antenna, I decided that it was just too heavy and bulky to fit. I was using a 1.5 inch pole and a TV rotator, and it just seemed to much weight for both of them. So I tried the 2m Watson X30 on that pole and it was far lighter and easier to fit, and it will catch less wind than that long Sirio. So the Sirio antenna was left to site somewhere else.

Deleting five paragraphs of explanation, let me skip several months to the point where I found that the Sirio was not working properly, and neither was the coax which fed it. So I have put up a Sandpiper 5/8th with a ring base on top of my main mast, until such times as it can go up above the 6m beam. This is at the risk of blowing up the GaAsFET front end on my SSB set-up, or perhaps the 100W from the SSB set-up killing off the 4m FM rig. Putting two antennas on the same mast, feeding two sensitive rigs on the same band is a risk, but so far so good.

Anyway, the 5/8th works 100% brilliantly on the same pole as the yagi.
Hopefully it will last there until the other mast is ready to take it. It has a ring base, so it is quite difficult to see the "ground plane", and hopefully the 4m yagi will not "see" such a small horizontal metallic ring right above it.

Having got all this underway, I heard that the 4m Anytone AT-588 was available again. The small low band rig can run up to 50W and gets great reviews. So I bought one, and the supplier was excellent. He is based in Ballymena in GI, and he sells them on eBay for the princely sum of £118, and offers a personal service. Not only does he test each rig, he sends it by next day delivery, and he checks to make sure you are happy that they work. He only imports small batches from time to time, and they sell out very quickly.
The AT-588 may be more familiar to many as a 2m or 70cm rig, and it has appeared in those versions from time to time. This low band version has all the features of the others, including tone burst, repeater shift, DCS, CTCSS ......

So why do I need a new 4m FM rig? Good question. My existing Anytone AT-5189 has given many years of troublefree service, but it is not the easiest thing to use. For example, to alter the volume you have to push the channel control and then adjust that knob, which is not easy when you are trying to work someone (I kept changing the channel by mistake and losing them). The AT-5189  is clearly built with PMR use in mind (taxis and commercial vehicles). Selecting scan required four button presses and selecting a menu item, but then not many taxis scan the band.

On the other hand, the AT-588 user's manual starts with an explanation of how to use it for amateur stations. The 588 has a proper volume control, a better display, and a wider selection of useful options on the microphone keypad. And unlike most PMR rigs, the 588 has the S meter which the 5189 lacks. Well, S meter is not the right name, but four LED blocks, which is as good as most FM rigs these days.

I am not sure how useful 50W will turn out to be. The rig gets quite hot on the highest power. I have positioned it to get some benefit form the fan I have on the FT-817. Until I move the antenna onto a separate mast, I will stick to 25W to spare the FET in the pre-amp on the SSB rig.

The size comparison between the two Anytones is quite striking. No doubt moving the loudspeaker to the top rather than being forward facing makes a big difference to the layout. The newer rig is on the top:-
The new AT-588 is deeper, but that is not a snag in any application I am likely to use:-

Initial contacts suggest that the AT-588 maintains Anytone's reputation for sensitive receivers. Both of them are maybe a bit TOO sensitive, as both rig can be overwhelmed by HF WSPR transmissions in my shack, but then plenty of rigs have problems with that. I do insist on transmitting on three bands at once.

Most 4m FM rigs have an ancestry which can be traced back to commercial rigs rather than amateur roots. And so the otherwise excellent AKD/Garex/Spectrum rig started out as a marine transceiver, and both of these Anytones are clearly derived from PMRs. My Wouxun handhelds are the sort of thing you see on construction sites. However, all these modern rigs seems to perform much better than the old converted PMRs we used to use. From Pye Cambridges to Philips FM1000s, they were discarded after years of use and were old technology when we got our hands on them. At least these ones are modern and well equipped.

I am not sure whether to let the AT-5189 go in a sale or locate it in my car. It would certainly perform better than the handheld in the car, but permanent fixings are not easy to find on modern dashboards.

And finally a word of warning. Don't make the silly mistake I made.

Don't change the coax, the antenna and the rig all at once. Then if you cannot hear someone (because he has turned his power down and forgotten to put it back up, but I didn't know that) you won't know what to fix. And you might end up changing everything, only to find that the main problem was at the other end.



Monday, 14 September 2015

Should I keep my Flex 1500 and what about the IC-7300?

Edit - see later IC-7300 review for my views on that rig  ...

Well the solar storm seems to have quietened down after 5 days of raging and weakening, then raging again. However, tomorrow looks interesting ...

There has been a storm raging in my head about my Flex 1500.

Now let us get this straight. The Flex 1500 is a great rig. It has done everything I asked of it, and I have no problems with its operation.

The problem is that I bought it to act as a transverter driver, and now I find myself not using the transverter. So the Flex has become an HF rig, and I do not need another HF rig. I am finding that it is not switched on for days on end.

When it comes to HF performance, it out-performs my FT-817, but as I already set out in this blog, the FT-817 is a definite keeper. Although the 817 cannot match the Flex for either receive performance or transmit power, it has other benefits, such VHF and an internal battery.

So basically, now that I am not using the transverter, I have two similar rigs. One of them, the one which was bought for the transverter, is surplus to requirements. It is a pity in a way, as the Flex is a very good radio. I like the idea of keeping an SDR in operation and being able to benefit from that excellent panoramic display, but not if it is just sitting here turned off most of the time.

Looking further ahead, the concept of putting a dedicated SDR into a rig case seems to be gathering pace. When we first saw SDRs, they were do-anything rigs which you attached to your computer. That is a logical way to go as it allows you to configure the radio in many different ways, and use the computer display for panoramic monitors, control, and so forth. But there are situations where a rig contained in a box which works without a computer is what you want. The development which makes this work better is the touch screen display.

Touch screen displays have been developed for the tablet computer market. They were troublesome to start with, but are much more reliable now. My IC-7100 has a black and white touch screen display. I find it easy to use.

A lot of the cost of making a rig is the cost of putting buttons and knobs on them - causing manufacturers to try to reduce the number of buttons - and hence Yaesu's infamous function table. So rigs with lots of functions cost a lot of money because they have so many buttons and knobs, rather than the functions costing a lot in the first place. With the touch screen you can reduce the number of buttons to a minimum.

Also, with a touch screen display you can provide access to a lot of functions, and thanks to the ever-falling cost of processing power, include a lot of the features which otherwise you would control on a computer with an SDR. OK, you are duplicating the display in the rig which you already have on your computer, but maybe that is what you want.

Latest rig to develop these ideas is the Icom IC-7300. This has just been announced in Japan and there are not many details. It looks like it will be at least six months before it reaches the UK and the cost is predicted as about £1000. It looks more like a £1200 rig to me, so we shall see what the exchange rate means for the price when it arrives.

It looks like a pretty standard HF transceiver but it has an SDR at its heart and a panoramic display as part of the colour touch screen. This panoramic display is small and no doubt restricted in what it can do, but it is still a step forward in a rig at this price. The SDR construction should allow updates and improvements to the firmware over the Internet.

The display may not look terribly advanced but the point is that either such displays were only available on rigs at twice the price, or were even more limited by requiring "sweeps" of the band. This one claims to offer full real-time panoramic display. Which means a display like the Flex and other SDRs, but without the computer being needed to show it.

Apparently, Icom are saying that you can touch the screen and using your finger, pull the rig frequency across to reach some signal you have seen on the display. I can do that with the Flex, but of course needing a PC and a mouse to do it. That is a very useful feature. However, is the screen so small that it might be difficult for amateurs with 60 year old eyes and stubby fingers to make it work?

Personally, I would like an option to do both approaches - allow the display to be output to a computer screen and allow control from there. And I still want it to work without a PC as well, if using it portable! It is not clear if that can be done or not, but I suspect not. Still, never mind about that, it looks a good prospect.

In my mind I have been comparing the IC-7300 with my FT-450. It would solve the 450s odd filter quirks, I bet it has a better receiver than the 450. It is twice the price of the 450, offers a panoramic display and covers the 4m band too. I am comparing a previous generation rig here (FT-450) with the latest technology (IC-7300). Newer looks better, but it is more expensive.

Maybe one day I would rather have an IC-7300 in place of my FT-450. But, my IC-7100 has various "issues". Would that put me off the IC-7300? No. I need to see that screen in action. But the general idea of an SDR style-rig in a stand-alone box with a display on the front rather than using a computer as well, strikes me as a good approach.

Fortunately, I do not  need to think about it for a while and my present set-up is fine for now. Too good, as I have a Flex 1500 which I do not really l need. Still, it is something to think about, which always whiles away the winter evenings.



Saturday, 12 September 2015

Solar Storm continues, CW and my paper logbook

Celtic people have a  bit of a reputation for being dour. Miserable would be another way to put it. Now, I am not saying that national stereotypes really work, but I do seem to have a thrifty, make do, determined streak.

Back in 1974, when I was an SWL just about to become G8JWG,  I trudged round to the RSGB HQ which was then in Doughty Street and bought two log books.

I am shocked to have to report that there are only two pages left blank. I have had to resort to buying two more. These two had better last 40 years too.

There was another logbook at some time, but I have lost it. And these days you do not HAVE to complete a log for every contact. I am selective and leave out every WSPR transmission and all those VHF FM ones with people down the street. Just as well, as I can clock up 1000 spots on WSPR overnight.

So I am still writing things out by hand. No automatic logging here. I have Software Defined Radios, 8 core processors and the like, but the log remains longhand.

I will try to scan this notable event in, but I am not sure how well it will show up here:-
YES, a CW contact! Just below what is a routine tropo SSB contact with GM0HTT in Orkney on 2m (IO89 367km), is a 4m aurora contact with G3LVP in far-away IO81 (440km). He gave me 57A and I gave him 59A.

CW! Every six months or so it happens. Old fashioned CW and a hand written log. The only thing I have never tried from that era is a spark transmitter.

I cannot knock CW for working well during an aurora. There is no tone, just a swooshing noise. Normal phone is often unreadable. So CW still has its uses.

I do not use CW often enough to get good at it, and honestly I cannot really be bothered. So it will no doubt remain a sort of twice-yearly surprise.

Believe me, if there was a data mode which worked in an aurora I would use it. But sadly for me, CW is the best bet. It would not matter except that I am not very good at CW.

The solar storming has continued and with the arrival of a new sunspot as well, the flux index has climbed to 96. With the aurora pulling HF conditions down, and the higher flux index pushing them back up, we are in the classic tussle with active solar activity being both good and bad at the same time. Showing the good side of it on 10 metres was a four hour opening this morning after 05:00, taking in Spain and Germany, down to about 200km distant. On 10 September this must be pure F layer DX, associated with the higher flux index:-

2015-09-10 06:58  GM4FVM  28.126112  -24  -3  IO85wu  +33  1.995  FR1GZ  LG79rc  10097  6274 
 2015-09-10 06:52  FR1GZ  28.126077  -24  -4  LG79rc  +37  5.012  GM4FVM  IO85wu  10097  6274 

10097km to the Indian Ocean in 10m in the middle of a geomagnetic storm. Interesting, as it is pretty well South of me, and no other DX was heard North, East or particularly West where the slightest opening brings in scores of Stateside stations.

It seems as if the auroral type conditions which create HF blackouts, affect Northern DX first. I guess the same thing would happen in reverse in the Southern Hemisphere, but there most land masses are further away from the pole.

So if I was only interested in working FR1GZ then I could almost think that a geomagnetic storm was not underway at all. But try to work anybody further North of the equator and it all goes quiet. Or so it seems.

As I write, the Solar Flux Index is 93. The solar wind speed is 587 which is pretty high. Unlike yesterday when the Bz was very minus but the wind speed was low, this time the wind speed is high and the Bz is -0.3. So now if the Bz (the magnetic polarity of the solar wind) turns a bit more negative, then I am in business.

So let us see what another day brings. More CW? I doubt it. But if I get the chance then you never know.



Friday, 11 September 2015

Aurora Watch continues - does Solar Wind clear its own path?

SolarHam says "a geomagnetic storm watch is in effect for the next 24 hours".

Gee whizz.

We have had three days of blasts and bursts from the sun, and now we face some more.

Apparently (and I only have a partial understanding of the process at work here) a prolonged blast of high windspeed can "clear away" a lot of matter in the background solar wind between the Earth and the Sun. Therefore what would otherwise be less significant, later, bursts of increased windspeed can present themselves on Earth with fairly nearly all the energy they left the Sun with. This means that the later blasts might have more effect when they reach here.

I have this impression that the "space" part of  the expression "outer space" means that there should be nothing between us and the Sun. Pure vacuum. But of course we know that there is the solar wind, and dust, and all sorts of meteorites and bit of left over comets etc. In fact lots of "stuff" in there.

All the same, the area between the Sun and Earth must be pretty empty. It might not be true "outer space". Outer space would have a "hard vacuum", with very little material at all. But the sun is a gas body in the process of nuclear reactions, it is not solid, and so it leaks some material into space all the time. I just think it might be unwise to compare it with the air around us, so we should not expect things to work the same way. But compare it is what I will do.

Just for a moment lets us just think of  this a bit like wind on Earth. So just as the space between me and the Ayton church is full of material (air), so let us think of the space to the Sun as being full of similar stuff (but at very low density). I suppose you could imagine a burst of wind pushing the other material in front of it. While a slow moving burst of wind on Earth might be slowed down by the material in front of it, this could happen in space. And behind a fast moving burst there should be nothing at all really, until the Sun releases some more slow stuff to fill the space. But if the Sun then releases another quite fast burst of material, it will proceed freely towards the Earth.

In other words, I could hear the Ayton Church bell more clearly if an earlier high speed wind had cleared away all the air between me and it. Which would be good (apart from me having died because of the temporary lack of air).

All that sounds a bit homespun and unreal to me. The effects of the solar wind are not like bell sounds. It is not modulated in that way. The whole air supply does not come from Ayton church and you cannot "clear it away". This comparison has gone too far. All the same, I have seen the idea written down and comments recorded like the first blast "cleared the way" for the second blast. The density of the solar wind is so low, how can anything effectively clear it away? On the other hand, the Solar Wind is made up of particles of matter, with momentum, which would be subject to being accelerated by something coming up from behind.

So let us see over the next 48 hours.

Certainly there has been plenty of blasting for the past few days to clear the way (if that happens). Whilst it has gone up and down, two days ago I was hearing the 70MHz beacon on the Faroe Islands (OY6BEC) and the Carrickfergus beacon in northern Ireland (GB3CFG) by aurora. I also heard a Faroes station on 2m aurora and Norwegians on 6m. AND NO CONTACT RESULTED. Grrr. Beacons everywhere, or CW too fast for me to answer, nobody to actually exchange 2-way messages. Good stations heard, nothing worked.

Another classic auroral effect is Sporadic E where you would not expect it, such as to the North of me at night. This image is my WSPR map on 10m at 22:28 on 9 Spetember 2015 :---
Sporadic E contacts at a clock time of almost 11:30pm. No doubt somebody will now tell me it was triggered by the Jet Stream (tee hee, old joke, let it go, Jim), but this is a good sign of geomagnetic disturbance. This solar activity produces both auroral scatter signals and Sporadic E. And as WSPR can be used to indicate Sporadic E, that is where you find me after an aurora.

In between the blackouts there was some good Sporadic E to be heard after dark too:-
2015-09-10 19:34  GM4FVM  28.126069  -29  0  IO85wu  +33  1.995  EA8BVP  IL28fd  3261  2026 
 2015-09-10 19:26  GM4FVM  28.126069  -18  0  IO85wu  +33  1.995  EA8BVP  IL28fd  3261  2026 

Was that "Auroral Es" or was that just general Es triggered by the geomagnetic conditions? Is such a distinction useful? Well, usually only northern Es at Aurora time is called "Auroral Es" of "Polar Es", but this type of thing looks to be related as well. EA8 (Canary Islands off the coast of Africa) could hardly be called "Polar".

By 10 September it seemed to have quietened down:-

Appearances can be deceptive. One element in the mix seems to be not just the strength of the wind and the magnetic orientation, but the variability. It is the "disturbance" rather than the "absolute" levels which often produces good radio results. Those seemingly flat magnetometer readings were actually during a period of high wind speed, it was just stable. Maybe it will change. SolarHam's warning of an aurora watch on 11 September for 48 hours looks interesting.

So, the show goes on. Let us just hope that something turns up which means I can actually WORK someone on the radio.


GM4FVM of the interplanetary magnetic field (IMF) has shifted south this evening. The solar wind speed also increased to near 500 km/s. A geomagnetic storm watch is in effect for the next 48 hours.Bz component of the interplanetary magnetic field (IMF) has shifted south this evening. The solar wind speed also increased to near 500 km/s. A geomagnetic storm watch is in effect for the next 48 ho

Wednesday, 9 September 2015

Solar influences on radio and the latest weak aurora continues

There was another mini-blackout on 40m last night, but it had cleared in time for me to hear ZL3PX at 06:18.

The apparent contact due South is a false spot. These happen occasionally.

It has take me quite a while to get to grips with what happens at the Sun when auroras occur.

I look at it as three separate things:-
1) The Solar cycle
2) Sun Spots, mass ejections and coronal holes
3) The Solar Wind
... and this is the simplified version (!!!)

1)The solar cycle.
We all know about the 11 year cycle, which is really a 22 year cycle which switches polarity every 11 years. Right now the last peak, which was about 2 years ago, has passed. The solar activity, measured by the number of sun spots visible or the Solar Flux Level which measures roughly the same thing, is on the decline.

Most of us also know that the peak of the sunspot cycle is when there are lots of sunspots, and this is good for amateur radio. True? Well, partly. Eruptions from the Sun, from Sunspots etc., also cause blackouts on HF, although in general they are a "good thing". Those of us who work on 10 metres and on VHF like the associated Sporadic E and aurora communications which eruptions bring. So they may cause HF blackouts, but they also cause VHF openings.

And then there is the issue that while lots of sunspots are good, we only need one good one for good conditions. If you think about it, the Sun is about 150 million kilometres from the Earth. We are just a dot in one small corner of the 360 degree, 3 dimensional, field around the Sun. So for a lot of the time anything leaving the Sun will fire off into "empty space". It only takes one large sunspot in a "geo-effective" position (i.e. pointing towards Earth), to have a big effect. So while more sunspots are good, more geo-effective ones are even better.

Most graphs of the solar cycle you see are "smoothed". In reality the solar flux varies from day to day, and from a radio point of view, even at low points in the cycle you can get good conditions at times.

So the message is, don't abandon hope as the cycle declines.

2) Sun spots, mass ejections and coronal holes.
Sun spots and coronal holes are features we see on the Sun. The Sun does not have a conventional surface like the Earth, it is made up of highly energetic plasma (gas which can conduct electricity), so material is leaving and heading into space all the time. There is no surface to keep everything inside the Sun, and the plasma is churning about rather like water in a boiling pan. All this is driven by nuclear reactions inside the Sun.

Leaving the Sun all the time is energy, which we see as light and feel as heat. It includes very high energy photons, such as ultra violet light and gamma rays, which luckily for us get absorbed by the upper atmosphere. It is these high energy particles which produce ionisation in the F layer and thus allow HF propagation. This stuff is pure energy, electromagnetic radiation, which travels at the speed of light and arrives here from the sun in about 7 or 8 minutes. So if there is anything which leaves the Sun we can see it very quickly.

Also leaving the Sun is the "solar wind". Unlike the energy, these are particles of matter, so they have significant mass, and they take longer to reach Earth. This can include electrons, protons, and ions of lots of elements, but mostly helium and hydrogen ions.

(At this point I doff my hat to Einstein and his equation e=MCsquared - the energy carried by the photons has some very small mass while it is in motion, but I am sure that my distinction between energy travelling at the speed of light, and particles of matter travelling a slower, variable, speeds, is clear to most people)

So, when there is an eruption at the surface of the Sun, often associated with a Sun spot, we can see it as the burst of electromagnetic energy reaches the Earth. This burst is over and above the normal background level of energy leaving the Sun. That energy burst can disrupt HF communications.

There may, or may not, be a mass ejection associated with this event. The mass ejections are the particles, a sort of Solar Wind gust into space, once again over and above the usual wind level and maybe a lot faster and more powerful.

Depending on the strength of the ejection, the material can either slow down and get sucked back into the Sun by gravity, or pass on into space (technically, if it exceeds the "escape velocity"). Then if it is very energetic it will head away with a lot of momentum and maybe reach the Earth in a day - that would be the sort of thing which will produce auroras and more blackouts. Or it may be less energetic, travel through space more slowly, and take three or four days to reach us, in which case it might or might not have much effect. And of course, it might not be directed towards Earth in the first place. Looking from Earth and working out which one is which is tricky.

3)Solar Wind
So this brings us to the picture with us sitting here on Earth. The Solar Wind brings particles to us all the time. Since the dawn of the satellite era, we have been firing up probes which can give us some sort of a lead on what is happening. We can measure the Solar Wind speed. You will find it listed on SolarHam, and there is a link to that on the bar on the right. If it it is, say, 200, you are seeing background wind. The Solar Wind is more complicated than it looks, with at least two different components, but we do not need to get into that at the moment. The Sun loses about one billion kilograms per second, but there is plenty of Sun there so it is not going to fade away just yet.

As I write the Solar Wind is 409.6, which is elevated. For a nice aurora I like to see it over 500. It also has a magnetic polarity (the one we watch is the "Bz" figure) which needs to be negative for a radio aurora. Right now the Bz is -8.2 which would be great if the wind speed was higher. So today, if the wind speed goes higher, I might be in business on VHF. As it is, this combination of elevated wind speed and -ve Bz is causing blackouts and poor conditions on HF.

The Solar Wind can be background wind caused by the general loss of material from the Sun, added to sometimes by these sudden burst of high-speed material released by mass ejections coming from sun spots or coronal holes (or other similar issues too complex to deal with here). The coronal holes are features which tend to recur every time a particular face of the Sun is towards us. The Sun rotates, but at different speeds at the equator and the poles, so the calculation is tricky. Sun spots also circulate round the Sun, but they appear and disappear over time, so not all make it round for more than one rotation. To some extent you can predict the return of auroras based on the rotation of the Sun, particularly those caused by coronal holes, but that is not a very reliable prediction.

The Sun releases energy and particles, and broadly the energy is good for HF and the particles not so good for HF. This happens all the time, but sometimes there are significant eruptions which release extra bursts of energy and particles. The particles take time to arrive, but not so long if they are high-energy and therefore travelling faster. The particles can be good for VHF by causing auroras (and also helping Sporadic E). Slow moving particles can take days to arrive, and cause poor HF conditions and don't do anything for VHF. But high energy particles reach us quickly and can cause auroras.

Lots of effort has been put into measuring and predicting the arrival of mass ejections. It is not just auroras they cause, but they can disrupt satellites. Given enough warning, satellite operators can deflect, turn, or even power down satellites which might otherwise be damaged by the high energy particles. At the same time, we need to be able to predict the arrival of such events because power and IT systems on Earth can be damaged by them.

I always love this bit. Someday, we may have a recurrence of the "Carrington event". A big mass ejection of high energy particles arrived and caused a huge aurora. The telegraph system was disrupted and I missed a great chance to work auroral VHF (this was in the year 1859, so no radio activity then). You can find info on that event here. When I was at college we were told it was a "once in a hundred years event". Now we are told it is a "once in 400 years event". But it will just take the right sun spot(s) to be facing us, and that might happen at the bottom of the sunspot cycle - less likely that at the top, but who knows?

Cheer up. It might never happen ...

... but I bet it does someday.



Tuesday, 8 September 2015

I have returned to an aurora

I am back.

I was away for a while in France (no radio) but now I have returned. No thanks to the French national railway company, SNCF, which kindly replaced the sleeper train I was due to catch from Rodez with an ordinary train, but still, back I am.

It is not fun sitting up at night when you have paid for a couchette.

7 September produced a nice aurora. The event had been likely as the solar wind speed was elevated and it certainly looked for most of that day as if something or other might happen.

First real sign I had of it was hearing the GM8RBR beacon in Skye on 70.100MHz. I also heard the GI 2m (GB3NGI) and 4m (GB3CFG) beacons making an auroral sound.

A CQ on 2m SSB at 15:53 produced a quick QSO with Andy GM4JR, and after that I switched to 4m and worked G4BWP, G8GXP, G4IOQ, GM4JR and GM8RBR. I also heard Henning OZ1JXY, calling Andy GM4JR. By 17:37 it was all over on VHF.

Not on HF though. The classic consequence of an aurora, an HF blackout, quickly followed. Usually on 40m WSPR in a ten minute period I might transmit once and be heard by 10 stations, and listen for 8 minutes and hear ten others. On 7 September, the effects of the aurora meant that by 20:40 I was only hearing two stations in 10 minutes, and by 21:10 I was hearing nothing. 40m is odd without all the whistles and noises. The noise floor fell by 20dB. I did not hear another station until 00:04.

Almost three hours of silence on a 40m evening session is pretty unusual.

It was then a quiet night for US and Canadian stations on 40. Usually they come in after midnight, on 7/8 September I had to wait until 05:00 to hear the first one.

The solar windspeed is still a bit high, but on 9 September I am getting 2 way to and from VK on 40. The map looks pretty well back to normal for 19:00, a bit before the trans Atlantic path opens.
I was speaking to Bob, G3KML, who said that he was reluctant to go on 40m as he did not have enough space to put up a "decent" antenna. well, I do not have a very "decent" antenna either. Just a wire dipole very low down. But I am still enjoying it.

Into every life some rain must fall. If I am to work the aurora on VHF I need to accept the blackouts on 40m. But I try to keep my interests in the hobby widely separated, so when one thing does not work, something else might.