Thursday, 25 May 2017

Meet the VHF Linear Amplifiers and general update

In reverse order (as is so often the case here).

Why reversed? Because I am "contrary".

By now (25 May) the Sporadic E ("Es") season is well underway, and every good VHF enthusiast has been filling their boots.

As an example yesterday the Es opening started at 08:44 and ended at 22:40 when I turned off and went to bed. I am not sure how long it went on after that. If you looked during late morning and late afternoon then you missed the best bits. There was a lull from 13:02 to 15:10. A classic two phase day.

I had 350 WSPR spots on 10m, as follows:-
24 hour map of WSPR spots at GM4FVM starting 09:00 24 May 2017
This usually provides a good guide as to where to point the VHF antennas, as well as telling me when it was the right time to go to Morrisons to buy bread (i.e. during the lull). The Seeded Batch is a good loaf and it will be nice with a boiled egg for lunch today. Just waiting for 10m WSPR to tell me when to put the pan of water on to boil. Wait for the lull to start. Don't want to miss ANYTHING.

There is a danger here that a guy could get obsessed. Not me of course.

I had very few contacts on 6m yesterday, and none at all apart from locals on 4m or 2m.
VHF stations worked at GM4FVM on 24 May 2017
I was somewhat hampered by local 6m QRM which blotted out several DX stations which I could hear in the clear. That tends to make me move on to JT9, which is a less popular mode.

The opening on 24 May was notable more for its length than anything remarkable. For example, I worked F1ABL on 6m at 22:00 and SP6IHE on 10m at 22:30. During the QSO, SP6IHE broke off to work a W station and then returned to finish with me. Some stations worked into the US on 6m but not me.

The few days which preceded this produced more variety, including a couple of German stations on 4m. Their 4m authorisation lasts until the end of August though so far I have not heard many, not even on meteor scatter. I am trying a different map background, just to prove to myself that not everybody speaks English.
VHF contacts at GM4FVM 18 to 23 May 2015.
As the Es season progresses I would expect more double hop and more openings on 4m plus possibly the odd one on 2m.

For most of yesterday, apart from calling CQ on 4m, I sat and watched the whole thing unfold. It is a remarkable aspect of nature. You might expect it to move West with the Sun - it doesn't (other than in a vague general way - it opened here due East last thing before I went QRT). You might expect many stations to seek out DX, whereas they seem very happy just to work the shorter distances.

Yesterday it started early and ended late - today it might do the reverse. In fact it probably will do the reverse just for badness, as the one constant feature seems to be that the same thing never happens two days in a row. These are the things about Es that amaze me and keep me watching for hours.

I guess I am just easily amused.

Better still, I spent some time trying to get the tone burst working on my £8 Baofeng 888 handheld. I never even knew it had a tone burst. I had a conversation with Ian, GM4UPX, who knows about them but so far it shows no sign of wanting to turn the tone burst on. It seems to be set by the software (just as well as that rig has no readout nor many controls). Ian says he has got it to work so more conversation there soon.

Then again it was good to hear from Chris, GM4ZJI. Chris has migrated towards 2m satellite operation which is a great idea but I am not there to hear him. Still, he has put up a 4m vertical and we had a "part text/ part phone call/ part QSO". A vertical is a good way to get involved on the Es as well as for FM contacts. Good to hear him too. I look forward to further chats.

Funny really. This is a hobby about communication, but we often sit alone in stuffy little rooms and ponder to ourselves about things. We set up computers or solder things together, and we often forget that conversation is very helpful. At least I have a few sensible people to chat to, and I am grateful for that. The little things matter - Richard, GI4DOH, must have seen me on 10m via the cluster at 23:06 local time last night and he sent a friendly e-mail.

Speak for yourself Jim, not everybody's shack is stuffy.
My linears are a motley bunch.

There was no strategy behind buying them, and in fact I am not keen on linears much at all.

For Es working, a linear is not that much use. Just like Es, auroral signals are often strong too. Tropo working here is limited by my site and if I cannot hear them there is no point having a linear. It is when it comes to meteor scatter that I felt the need for more power.

Meteor scatter signals can also be quite strong, but only for fractions of a second. They tends to start quite strong and fade away. By using more power you extend the time that the station at the other end can hear your signal. It is this time extension which makes the difference rather than the level of the peak "ping" at the start.

I do not have any 400 watt or larger amplifiers. I simply wanted to raise my power to be in the same order of magnitude as the stations I was working. For meteor scatter this turned out to be 200W on 6m and about 150W on 4m and 2m. I have not found any need to go further.
GM4FVM linear shelf as at April 2017
The photo shows the linears in a previous layout. Since then, as the shelf keeps sagging under the weight, I have moved the 6m linear onto a nearby shelf.

Just about the only thing which they all have in common is that they are all hard wired separately to the PTT line for their various dedicated rigs.

I ended up with this strange line-up mostly by chance. Back when I used transverters for 4m I could produce about 25W output. This was useful on meteor scatter, but not quite enough. I needed something a bit more muckle. So about 5 years ago I bought a TE Systems 0610G 70MHz linear rated at 130W, which happily ran at 100W if I added a pair of cooling fans.
My TE Systems 0610G for 70MHz now sadly sold.
This linear did great service for five years. I had no particular reason to change it, but it was replaced rather by chance.

My previous 6m linear was a Bremi valve CB linear converted for 50MHz. When I finally got fed up with the instability and unreliability of this vintage monster I decided to buy a Linear Amp Gemini 4 to replace it.

The Gemini claims to produce 270W on 6m, with me hoping to use about 200W for meteor scatter. While I was waiting for it to arrive I contacted a GM operator who had one, just to ask about it. He mentioned that he had a 375W 50MHz TE Systems 0552G which he was not using. I quickly arranged to buy that amplifier and it is the one on the left on the shelf. The Gemini then took up its place on the right as the 4m amplifier. So the Gemini replaced the 70MHz TE and its 300W theoretical maximum output allows me to raise my 4m power to 150W. In between is a Microset SR200 2m amplifier which I use at about 150W.

The Gemini comes complete with integral mains power supply and (noisy) fans. The TE linear, on the other hand, comes with a 12V input and no fans. The TE handbook states that with a high duty cycle mode you should fit fans controlled by a 12V TX output available from the socket on the back. It recommends using a timing circuit to keep the fans running for longer than just the TX periods. Being a good amateur who does what he is told, I tried to fit a timed relay only to find that the 12V output from the linear could not provide enough current to lift the relay I had.  At this point it seemed simpler to follow GM4JJJs suggestion and make the fans temperature controlled.

Cheap temperature controlled relays are available from eBay for about £4. These allow you to set a desired maximum temperature as measured by a remote wired sensor which I placed at the bottom of the linear heat sink near the output device fixings. The LED readout on the chip allows you to set your desired temperature and it then switches the fans to maintain the range to within 2 degrees C of the desired level. In my case I set it to 25C. At that temperature setting the fans come on within a minute of my first transmission and stay on continuously until after I have finished.
Cheap temperature control relay from eBay being fitted into an ABS box

It is a simple matter to fit the temperature board into a box, which you can equip with all the sockets you need. In my case, probably unwisely, I use phono plugs for DC supply leads, the fan leads and the TX 12V output from the linear. It might be best to use different plugs to avoid some wiring mix-up catastrophe but that seems to be my standard now. I make clear labels and hope that I read them! There are several sockets on the box for my fans and one which I use to illuminate the backlight on my 6m power meter. I cannot hear the fans so it is useful to have a visual indication that they are likely to be working.

When I comes to fans I really dislike the standard 80mm PC fans. I find them noisy and ineffective. For the TE Systems linear I use four 120mm fans. At 200W output this finds an equilibrium temperature of around 30C. At the quoted maximum for the TE 0552 is 375W, at which point it is drawing well over 50 amps from the power supply, it is running at about 33C thanks to the fans. Whilst the linear would be happy at 375W on SSB, on modes with 1 minute TX times it gets rather too warm internally.

I suppose if I went for screaming small diameter fans moving the air more quickly I could use more than 200W, but I prefer to under-run the linear at 200W. That way it stays nice and cool, (hopefully) linear and the power supply remains happy providing about 36 amps. The over-temperature switch fitted as standard inside the linear trips at 65C.

So that is the TE Systems 0552G. It runs happily and fairly cool at 200W. Apart from the switch panel supply failing as soon as I got it (the repair for which was described earlier in this blog) it seems to do well. Whatever caused the supply to fail to the switching circuit, I think that is also the cause of the lack of current available to switch the fans.  My bet is that despite what they say in the handbook, it is not capable of powering fans via the socket at the back for long before something fuses. Still, that is solved now.

It couldn't be that you put in too thin wire when you fixed the problem Jim? Aw no, that would be impossible.

TE might have used a socket type in more general use for PTT than the RJ45 socket they now use as standard. I built a break-out box for the PTT and fan supply. It might also have had "N-type" RF sockets. It might even have had the necessary fans already fitted (though a continuous duty rack version with fans is available). It had none of these things. I bought it second hand and so far to does the job nicely.

Moving on to the Linear Amp Gemini 4, it was bought initially for 50MHz use. As the TE linear turned up, I moved it to 70MHz. There it runs happily at 150W. It is self-contained, causes no heartache and runs away needing very little attention.

Drawbacks, well it is noisy, with the transformer, fans and the changeover relay all contributing. On SSB it is possible to trip the overdrive cut-out on speech peaks early in the transmission. I am pretty sure that this problem stems from an initial spike in the IC-7300 output. Reducing the power setting on the 7300 seems to function via the ALC. This arrangement can allow instantaneous spikes at the start of a tx period. This is a common issue with many rigs. If I set up the 7300 carefully enough it is not a snag, and it only affects SSB. I know another amateur who has the same issue with the Gemini, and others who do not. To my mind, this is a rig issue rather than a linear amplifier problem. That does not explain why two stations with the same rig and amplifier have different experiences, but then, am I am expected to explain all the mysteries of the Universe?

There is a simple reason why the spikes were never a problem with the TE Systems linears. TE Systems have no protection circuits apart from an over-temperature cut-out. You can never trip the overdrive limit by transmitting a spike into the TE Systems Linear because it has no overdrive limiter. Nor does it have a high SWR cut-out like the Gemini. You take a risk using linears with no protection, and I read that the TE Systems amplifiers have been prone to problems for this reason.

Dealing lastly with the linear in the middle, we turn to the Microset SR200. This is a 200W rated 2m linear. It has overdrive and high SWR protection. To produce the rated 200W output it needs about 50W drive. Like the TE Systems linears it has a built in GaAsFET preamplifier, but in both cases you can switch them out of circuit independently of the PA TX stage.

I bought the SR200 direct from Italy, and at the time I saved about 20% of the UK list price. In the four years or so since then it has worked without drawing any attention to itself. It never failed like the TE, nor tripped like the Gemini. It has always just worked away to itself.

The drawbacks for the Microset include that it needs to have fans fitted for high duty cycle operation. It never gets very hot, but then I never draw full rated power. It does not have a fan control output, so I will be installing another temperature control to its fans. For once I am going to try a variable speed control and we will see how that goes. You can buy fans with integral temperature control and remote sensors which I will try, though these have preset temperature ranges. I will be changing over to 120mm diameter fans at the same time. In the past I used the Microset with 2 small and 1 large fans with nothing more complex than a switch.

Strangely for a high-VHF item, the Mircoset is fitted with SO239 RF sockets rather than "N-type". These are easily changed.

I use the same 12V power supply for the Microset linear as  I use for the 6m one. This could be a problem if I accidentally transmitted on both at once, but that has never happened yet.

So back to the start. Why do I have linears? Because nobody can use a commercial rig at full output on meteor scatter QSOs and expect it to survive at full rated power. I drive the 6m linear with 8 W for 200W output, meaning that the rig only needs to run at less than 10% of its rated out (and the linear at just over 50% with added fans). On 4m it is 8W for 150W output, using just 16% of the rig's output (and again using only 50% of the linear's rated power). On 2m the rig provides about 25W. To try to get a lot of power from a rig on a regular basis is risking a very expensive item for little benefit.

Also, none of the linears is working near its full rated power. If, say, you took the manufacturers advice and drove the Gemini and TE with 25W and the Microset with 50W, you might get away without overheating them on SSB. However, you risk pushing them into non-linearity. Personally I set them up using a power meter, checking full power output and then backing the power off to well below the maximum possible, and ideally to 50 to 75% of the maximum.

To me anyway, linearity is very important. I do not wish to get a bad name for over-driving a linear amplifier. The drive levels quoted by a manufacturer will be maximum figures, and my meters are not sufficiently accurate to ensure that I do not overdrive the amplifier. So I tend to back everything off - and it saves the rig too.

There was a magazine article recently which tried to suggest that everyone should have a linear and run full legal power. It suggested that this was our duty as amateurs as otherwise our legal power limits would be cut. Well, if that is the case I am failing in my duty.

There is a school of thought that says that more power is just better in every situation. Sorry, but at 200W I have gone as far as I ever need or want to go.

I suppose therefore there is no logic in my choice of amplifier or the use I put them to. For now though I am fairly satisfied with them, and the results they deliver.



Thursday, 18 May 2017

Some more thoughts on JT65 as Es gets under way

1) The two phase theory
Someone asked me what time of the day he should look for Es.

It is often said that Es features two peaks during the day. I have already said that my examination of my logs shows no distinct pattern, though despite this I do think that the two phase theory has some usefulness.

So what am I on about? Well, of course Es is sporadic, and some days there is none (no phase at all), some days there is Es only in the morning or afternoon, or even the evening or night (one phase). And sometimes there are two distinct phases with a lull in between.

Recently we had an example where Es first appeared around 08:00. It carried on until about 13:00, then faded to return at about 17:00. So two phases could be noted, on that one day. The difficulty in trying to interpret this is that on one day the first phase might start at 12:00 and finish at 14:30, whereas on a different day the second phase might begin at 15:00.

How is the possibility of this two phase characteristic useful? Consider a day when I am working Es and at, say 13:00 it fades out. My 28MHz WSPR station goes quiet. All the Es clouds fade from the Es MUF on DX Maps. I can then do some of the more important things in life, such as perhaps writing my will, or changing the wheel on a wheelbarrow. I can be fairly sure that there will be no Es for about 2 hours. Maybe three hours, or it might not come back, you never know, but there is a definite gap.

The Es may have faded that day at 12:00 and I will be looking for a return later, maybe after 15:00. But on another day it might only fade at 15:00, in which case the clock starts from there.

So the concept is useful in knowing when there will probably not be an Es opening, rather than when there will be. There generally will not be another phase right after the current one fades out.

It seems to be impossible to predict (reliably) when the Es will start or finish. However, when it fades it does not come back for a couple of hours. Or so it seems to me. There might be  no second phase that day, but I know I have some time to do other things before I need to worry about listening again.

Let us imagine I have some gardening duty to do. I would routinely look in at the radio in case there is some Es about in the morning. If there is I can put off the gardening until the gap between the two phases. It is very unusual for Es to run for the full day, as otherwise I would never do any gardening. And that would be terrible.

It is said that we should look for Es in "late morning or late afternoon". After I read that I worked into Greece at 09:25. (Nice contact by the way, SV9CVY in KM25, 3091km. I have worked him before, but still a good one). That was not "late morning". Also not "late afternoon" was a contact with SM5CNQ (JO78) the following day at 22:21. You cannot make too much of one or two contacts, but looking earlier than "late morning" and later than "late afternoon" proved worthwhile there. They have a general point, there does seem to be a lull, but trying to pin it down like that is tricky.

If there is supposed to be a lull in early afternoon every day, I have already worked stations on Es at 13:25, 14:42 and 14:50 (F6ECI, OE5OLL, and EB1AO), which suggests otherwise.

So far, 37% of my contacts have been outside the "late morning, late afternoon" slot. I just think that it is not helpful to put labels like that on Es, which might have the effect of limiting the times people operate and thus causing them to miss useful contacts. 37% of useful contacts, indeed.

For this year's Es season, only one day so far has had a "classic" two phase double peak.

As always, I need to say that this is what happens at this QTH, it might be different where you are, especially if you are in tropical regions.

I cannot predict when to listen for Es. I cannot say that if the morning Es has faded out that there will be a second phase. However, if there is a second phase there will often be a long gap in between. The useful thing is that you know that you can go and do something else for a while.

Given that both wheelbarrows now have new wheels, what else can I do?
2) When to send you locator on JT65, and when to send 73?

Especially on VHF, JT65 can be an unwieldy beast. It takes six minutes between sending your CQ and sending it the next after having a QSO. In six minutes the propagation can have come and gone.
There is a shorthand way of doing this. I do not have any from today to show you, but I found this one in the FVM vaults, showing some Winter Es:
It may need to be clicked on to enlarged.

It goes :-
2) GM4FVM OH6WD +14dB (not his callsign and locator)
3) OH6WD GM4FVM R+05

That would save 2 minutes if I left it there. In the short Es openings which we get, 4 minutes is probably long enough.

However, I was still stuck with the idea that I should complete the QSO in the classic way, and I sent OH6WD GM4FVM 73. That was silly. I should have gone on to call CQ again. If I did that, OH6WD would have realised that I had got his RRR, as otherwise I would have repeated my report.

If you reply to a CQ without sending your locator, but go straight to the report, the station at the other end does not know where to point their beam (if they are using a beam). It will also set the QSO off on the opposite segment, so you are giving your report and RRR when otherwise you would just be giving the report, and the whole thing ends 2 segments early if you do not send 73. If you do send73 you find yourself listening to silence for a minute when you could have been doing something more useful.

Coming from HF JT65 you might find all this a bit brutal and dare I say it, impolite. Coming as I do from VHF meteor scatter, it is quite common. When your QSO could last over an hour to confirm six pieces of information you are accustomed to short cuts.

The way I make sense of the example above as follows:-

1) I had worked OH6WD before, so he can feel free not to send his locator.
2) If he can take a shortcut like that, he will assume that me calling CQ at the end is the same as the 73 message - I have your RRR and I am moving on. Otherwise I would have repeated the previous message.

I personally would only skip the locator if I had worked the station before. For example, I have worked OZ1JXY 65 times now, and he knows where I am.

By the same token, I would always accept seeing a CQ as a confirmation that the QSO is finished. I do not need to exchange 73s if it takes 2 minutes to do it, and especially as I already have his report and his R, and I have confirmed this by sending RRR.

However, if the QSO progresses the normal way then the 73 costs nothing in terms of time, so I will send it. It is his frequency and it is up to him to call CQ next, so I fill the empty space with a 73. If I reckon I have the time I always do the whole thing by the book, 73s and all.

Polite, what, what?

What I need for a QSO is

1) his callsign
2) his report
3) "R" to indicate he has my details

The locator is required if it is the first time I have worked him from that QTH, otherwise I can live without it. 73 is nice but not required if the other station goes on to transmit again.

Contests, of course, are different.

If I ever do skip the 73 and the other station fails to hear my CQ, then I send a 73. It is what I do, but I see from several postings "you are wasting your time!". Now where did I hear that before? Buggleskelly, where the Porter told Will Hay all about it n the 1937 film "Oh! Mr Porter". That film was based on an original play by the great Arnold Ridley.

Ah well. You remember things like that if wheelbarrow wheels are the only other things you have to think about.
3) Keep your head when all around are losing theirs.
During a strong opening, JT65 here turns into a bear pit. I have three locals within 5km of here, and when they come on I have little choice but to fall in line with whatever segment they are transmitting on. So long as we all stay together on first or second, and none of the four of us changes, then we are fine.

The snag here of course is that the best DX might be on the same segment. There is no rule applying to Es, as there is on meteor scatter, that beaming South and East is second, and beaming North and West is first. In any case, none of the locals has a directional antenna.

If I can work round this, I do. It is tricky though, with strong signals inside the SSB filter. There is not much you can do about it.

I often turn to JT9. There are not so many stations on it, but it is theoretically 2dB better than JT65 and it puts the locals outside my filter. You can often see JT9 signals appearing at the top of the JT65 waterfall. I find that JT9 is a useful mode to have.
4) The last few days
13 to 18 May 2017 50 and 70 MHz Es contacts at GM4FVM
Nothing to complain about there, though I missed openings into the Middle East and across the Atlantic. Not that I am the complaining type. I am a cheery, "get along with things" person. But there has been another major aurora warning and yet again nothing has happened yet. Maybe today. This seems to happen a lot lately, the conditions seem right for an aurora but nothing happens.

Ah well, even though there is a ton of Es out there to be worked, you just have to make the best of things.





Friday, 12 May 2017

JT65 Conundrum continues

In the interest of science, and at some personal cost to my energy levels later, I rose this morning in time to see how I would get on trying to see if DK8NE would hear my signal.
In fact, I had been reported earlier but I missed it.
Careful inspection that image, if you click to enlarge it, shows that I was reported at 04:10 too.

I would expect that at 04:10 there would not be so many aircraft around, and not much Es either.

You do not usually get me in the shack at that time either, and this sacrifice on my part for the benefit of science is something I will not let anyone forget in a hurry.

26 times I have been spotted by DK8NE since 1 May, but I have not worked or been heard by any other German station.

Not that I am paranoid, but I can see why people think that there is someone listening to their phone ...

I was even spotted when I was beaming East (again, today).

I had one decode each from two other stations today and worked no 6m Es at all, but I still managed to be clocked by DK8NE ten times. I cannot work anyone anywhere with a beam, but DK8NE can receive me fine all day on his loop.

To say that I was spotted ten times actually means I called CQ ten times, and I was spotted ten times. The only occasions I was not spotted was when I cut the power or after 15:19.

Some things I seem to have established.

1) No contact so far after 15:19 on any day. Not yet anyway, but I know it works fine at 04:10.

2) I tried WSPR from 21:00 last night until 04:08 this morning. Although G4CPD was hearing me, and DK8NE was hearing local stations (so both stations were working), there was no result after 6 hours. The power level on WSPR was just a bit over 20 watts, the most that I felt I could comfortably run overnight. Probably not enough power for a fair test.

3) I have poured over information on radio horizons for aircraft. From the figures I have seen so far an aircraft at 30,000 feet is too low for a path of 1000km. However, at 39,000 feet it might be possible. The site conditions at each end are hard to factor in, especially with Ayton Hill cutting me off in that direction. This is not my field of expertise (what is?) so I may have got the calculations totally wrong. Let's say that any idea I had of ruling out aircraft scatter on path grounds alone is looking shaky.

4) Multiple modes have been suggested. Yes, I can see how one propagation method can feed into another. However, for this to keep happening 10 times spread over an 11 hour period is a bit of a tricky scenario for me to envisage.

Does any of this matter?
No, not really. It could be aircraft scatter, or it could be ionoscatter, troposcatter, or a combination, or something else. The odd thing is that the path exists for so much of the day, plus it does not coincide with Es or any other opening.

I think, having got this far, I should shut my investigation down for now and see how things go over the next few weeks. Either it will stop, or something will emerge which pins it down once and for all.

I am certainly not trying again at 04:10 tomorrow.




Wednesday, 10 May 2017

Cruel, cruel Es, the DK8NE conundrum, and PSK Reporter

Since I wrote about Es on 4 May, until today, there has been no more Es here. Well, one isolated contact.

Quite a nice contact actually, not a new one, but good all the same, with UR5WCE (KN29 1873km) on 6m on 4 May.

Es is a cruel master. It can turn on and give you access to the world, and then again turn off and leave you fuming. Maybe that is why it is called Sporadic.

It is not just the presence or absence of Es on any one day which frustrates, it is most annoying when it is happening all around you and not involving you.
6m Es on 4 May 2017 - definitely not involving Scotland
The problem is when Es occurs and the cloud is either too close (depends on the level of ionisation, but generally less than 300km away), or too far away (variable, but definitely over 1100km is too far away).

The wonderful service provided by DXMaps then just becomes a goading match whereby Es taunts you by showing other people working 9K2 while you hear nothing. It is infuriating, and a product of living at 56 degrees North where the Es starts later and ends earlier.

Or it is just not coming your way. Lets face it, Es is very selective and can work here and not 50km away. Everything is down to the distances and the angles.

You may wonder if, on the days when Es is favouring me and ignoring you, am I sympathetic to your plight? Of course I am, but I am too busy working stations to mention it.

Be assured, your welfare remains my highest concern.

Then there is the more straight forward annoyance with Es. Some days it just does not happen at all.

I will not post up an empty map, but we have had an empty map for several days in a row now.

As Gianfranco, IU1DZZ, once put it to me, there is often Es about, but not always where you want it. This is very a profound thought. Of course it does what it wants and it does not bend to my will.

DK8NE (JO50, central Germany, east of Frankfurt, near Fulda) has set up a receiver to report several several modes which are relayed to PSK Reporter. More on PSK Reporter below.

The modes involved include CW, MSK144, JT65 and WSPR.

Having used MSK144 for meteor scatter for quite some time, I have become accustomed to seeing DK8NE showing up on PSK Reporter showing that he has heard my signal. No surprise there, as at 1000km he is at a good distance to receive meteor scatter signals from me.

What has surprised me is that since changing over to JT65 at the start (!?) of the Es season, I am still being reported by DK8NE. This cannot be meteor scatter, and although DXMaps is interpreting it as Es, it cannot be that either.
Typical spot from DK8NE, with no Es showing anywhere in Europe.

So let me run through the various propagation possibilities.

1) Tropo - no, not very likely on 6m, and no other reports of tropo at the same time
2) Meteor Scatter - no, JT65 does not support meteor scatter. Might be possible during an intense shower, but there were no showers at the same time.
3) Aurora - no, not with JT65 and anyway there was none.
4) Es - no other Es reported. Plus, Es is sporadic, but I have done this repeatedly on days with no Es.
5) F-layer - are you having a laugh?
6) Ionoscatter or Troposcatter - maybe?

Now Ionoscatter and Troposcatter are both known to be very reliable means of propagation. I may get time to explain the process later, but let us just say that ionoscatter occurs mainly in the D-layer and troposcattter in the troposphere (obviously), so these factors will set the probable distances reached.

With ionoscatter path are usually over 1200km ("not much less" says one source) , and with troposcatter it is 700 to 900km. Ionoscatter has a skip zone, whereas troposcatter does not, and I am not hitting any other station along the way (of what must be admitted to be a largely over-sea path). That might suggest ionoscatter, but so far I am not reaching anyone further away either, or perhaps there simply are no JT65 listeners in these places to hear me.
I am not going to suggest that I can reach DK8NE every time I transmit. Nevertheless, it feels like that. The PSK Reporter reports are automatically relayed to DX Maps, which makes it look as if I am regularly having contacts with DK8NE. Even I get surprised when I turn to DXMaps to see who is working anyone on 6m and I find that it is me and only me!

Looking up the DX Maps database (great tool by the way) I see that DK8NE reported me 9 times since the Es ended here on 4 May. 9 times in 6 days. The reports ranged from -1 to -22dB. Times are from 09:33 to 15:11 (not sure how significant that is). On the face of it, evidence suggests that DK8NE's logger is not on all the time, at least as far as I can judge from PSK Reporter. Nor am I, as I have not been trying for this path and I did notice one report arriving as I pointed to Spain, and another when I was beaming at Sweden.

More experimentation is needed on this. Is it just a stray result? I do not know. These scatter modes, whichever it may be, are usually stable and provide regular, steady, but weak signals. Yet, I am getting reports as high as -1dB, which is a level I might expect from Es. I am using a simple 3 element antenna (not the 5 ele, more on that another time) and he is using a 7 element. Also, I do not have a massive station and I do not run a kilowatt.

If DK8NE is using that beam, which way does he point it? The questions are legion.

So, more than anything, I am puzzled with this result.
PSK Reporter is another voluntary mapping system for data contacts. I already use WSPRnet (compiled from WSPR reception reports sent directly by users) and DXMaps (compiled by cluster postings, plus reports from some other sites including PSK Reporter).

You can find a link to PSK Reporter on the sidebar. It takes a bit of getting used to.

I find that the most useful information comes from the settings shown below:-

Click to enlarge image!

Anyway, you may play about with the settings as you wish.

OK, sometimes it gets a bit clunky. For example, clicking "Go" sometimes produces no result and then you need to click the reload button on your browser. Or sometimes it goes blank. But that type of thing does not take much away from its usefulness, which is considerable.

You can, for example, select a mode, such as PSK or JT65, and search for all the stations working others using that mode. Or click the "active monitors" link to find who is likely to be around - but beware as it seems to default to 12 hours for that one!

I find that it works very well in most situations. If you are using WSJT-X or MSHV you can click the option to report to PSK Reporter (though PLEASE, if you do that on MSHV, please keep your band setting up to date or your posting will turn up on the wrong band. Grrrr.). If you do not report yourself, you may still be reported by receiving stations, in which case you will show up only as a transmitter.

As well as a general propagation measure, you can use it as a "reverse beacon" network. In other words, transmit and see on the map who hears you. Nice as this is, it revealed that on MSK144 I was being heard by seven or eight stations but none were replying to my CQs. Clearly, many operators just leave their software running and leave the shack. Or maybe they just don't want to talk to me. Anyway, off to JT65 I went, where at least no replies really means nobody is listening. True amateur radio for me: loads of silence and time to ponder if the antenna has fallen down.

Modes covered include SIM and OPERA, as well as the JT modes and, of course, PSK.

It is time to appreciate all those who run sites like PSK Reporter and WSPRnet. OK, we get a chance to fund sites like Solarham and DXMaps if we choose to (and they are free even to use if you don't contribute). Others we just take for granted. But either way, these folks put in loads of hard work and the services they provide are really useful.





Thursday, 4 May 2017

Making the best of Es on VHF.

With the coming of May, on this Northern Hemisphere anyway, the annual Summer Sporadic E season ("Es") cannot be far away.

There have been a couple of openings on 10 metres, with Gianfranco IU1DZZ heard here for several hours each day. So I thought it might be time to set out how I manage it. I am not going to talk about the science of the process much, and instead concentrate on the operations.

The Annual Season Starts ...
The exact start of the season varies from place to place. Being located at 56 degrees North it tends to come a bit later here than nearer the Equator. But, broadly, it runs for 8 weeks or so on either side of the Summer Solstice (22 June). I am dealing with the Summer Es season here, though there are openings around Christmas and the odd day at other times, including after auroras.

Although there have been several weak openings, my first VHF Es contact during the 2017 season was today as I write this (4 May 2017). That was a JT65 contact with EA4WO in IN80 square, at 1734km. It was followed by a QSO with CT1FJC in IM57 (2142km). Both EA and CT were showing up on 10m WSPR, which gives me a clue to where to point my 6m beam.

What follows are a series of these clues plus some hints and tips. They work for me, but of course you can just sit back and work VHF Es as it comes. Most of this has appeared in this blog before, but I am pulling it together for this posting.

It all depends which band of frequencies you use ...
The level of ionisation in the E layer will affect the degree in which any particular frequency is refracted back towards the Earth.

When ionisation rises sufficiently to bend your signal back to reach ground the band "opens". This can be quite sudden with loud signals where moments before there was nothing. Hopefully during the day the ionisation will increase and signals will get stronger. And as that happens the ionisation may rise further to allow the next band up in frequency to open. This is a "rising MUF".

As the ionisation and the MUF rise futher, this most distant contact may disappear as other closer stations are heard instead. So the A to B path is present only at a certain level of ionisation, which will vary with the frequency used. Click to enlarge the image below if that would help.
 The same thing happens in reverse, with the higher frequency bands closing in turn as the "maximum usable frequency" (MUF) falls.

At a certain frequency the signal just gets refracted back to the ground and above that frequency the higher frequency bands will be closed. It is therefore the maximum usable frequency at that time.

Since the higher frequencies require stronger ionisation, they tend to open less often. My own experience is that my favourite bands tend to open during the Es season as follows:-

10 metres - almost every day
6 metres - every 2 to 3days
4 metres - every 3 to 4 days
2 metres - two or three days per year

So, if Es occurs more often on the lower bands, why go up in frequency to wait for an opening to arrive? The answer to that question is next.

Es is always better when ionisation is weakest ...
Yes, I know. It depends what you mean by "best". If you want to fill in lots of squares in countries which are well within the longest distance possible, then "best" would mean working loads of stations. On the other hand, "best" in this sense means working the longest distance.

Rather like F-layer propagation, Es gets to the best dx when the signal is radiated as close to horizontal as possible and it is then reflected by the furthest away ionised cloud near the horizon, and reaches a similarly distant station as it completes its travel (in other words, when the transmitted frequency is just on the MUF). This path is favoured when the band has just opened or is about to close as it is then that the bending is least and you can reach maximum DX. Generally there is only one station to work then, whereas if you want loads of stations to work then pick periods when there is stronger ionisation, though paths will generally be shorter.

So longer distance is definitely "best", and shorter distances are also "best". Marvin the Paranoid Andoid would appreciate that statement. As usual, click to enlarge the photos if that would help.
But this diagram is at one frequency, what if we use that information to bad hop?

Doing the treble ...
I use the information I gather on 28MHz WSPR to look for a 50MHz opening, then if things are good there, look for 70MHz and eventually 2m. It certainly beats sitting on 2m for 363 days a year waiting for the rare openings there. It is also possible to gather information from broadcast stations on the 88 to 108MHz band.
Doing the treble for me means following the Es opening up from 50MHz to 70MHz to 144MHz, making contacts as I go. This is usually only possible in the week or so on either side of the Solstice when ionisation is at its strongest.

As, by definition, the ionisation is weaker on the higher band, you often stumble across the "best" conditions as you move up the bands. And as it 2m there are only occasional short openings then they are often "good" if you can follow them - for instance contacts from here to Belarus and Italy. Not bad for 144MHz.

Moving down the bands after the higher ones have closed produces similar effects, usually with more DX around as they have been on the lower band all along (and missing the action).

Splitting the difference ...
DXMaps is an important resource for me. However, it depends on stations reporting contacts made. PSK Reporter is similar. If everybody sits around watching blank maps and nobody calls CQ then the maps stay blank.

However, if you see an interesting contact on DXMaps, how should you proceed? Well, I try "splitting the difference". Lets us suppose that I see an Es contact reported between an OH station in Finland and an EA station in Spain. Great. I need new squares in both Finland and Spain.
Imaginary contact similar to what might be seen on DX Maps.
If I beam at LA or EA I will almost certainly hear nothing. The signal is being refracted by a cloud of ionisation in the E layer midway between the two stations. So, I need to split the distance between the stations and try to work someone off that patch of E layer.
Likely path available (white line) based on the reported contact (red line)
Maybe I do not need Italian squares so much, but that is the likely path to open.

If you doubt this idea, here is some proof ...
Actual example from 70MHz DX Maps on 3 May 2017.
If you study DX Maps you will see these points where the cloud is located on a regular basis.

You can find the estimated ionised regions during an Es opening, by square, by clicking on DX Maps MUF ES tab.

It all depends of course as to how close to me to Es patch is. In my imaginary case it is nicely positioned for a good contact into Italy. If it was closer, I might hear nothing. Ideal spacing for Es clouds for best DX is about 1000km from me, which is an arc from SE Norway through to NW France.

Do the Es clouds move ...
Who knows?

If you look at DX Maps or PSK Reporter you will see the propagation move around. It is often said that the Es clouds appear to "move" North and West. I have never seen much evidence for this. The Sun is moving relative to the Earth (actually a product of the Earth spinning once a day) and it is the energy from the Sun which causes the ionisation. This would suggest that the patches of ionisation should "move" Westward. Look for yourself, but I find that most clouds tend to be pretty well fixed.

What does move is that the variation in the ionisation causes the path you can work to change, lengthening and shortening (and widening and narrowing in the process) , and that looks pretty much like the clouds moving from our perspective.

Then again, some clouds fade and others are made as the Sun appears to move in the sky, but the new clouds are not always to the west of the earlier ones, and may be to the north or south.

What sets it off? Now there is an issue for further discussion (but not here please). It certainly is not thunderstorms over the Alps, as we once read.

Are there two peaks of propagation during the day ...
Who knows?

A couple of years ago I tried to plot out all my contacts to see if there was a two peak pattern. I found no pattern at all.

For me it is, to use the famous Scottish jury verdict, "not proven" (other countries have just guilty and not guilty, but we place people we don't like but who cannot be found guilty into a nether land of doubt and suspicion for the rest of their lives).

If it exists, I sense a vague effect between the first peak at about 11:00 to 13:00 and the second from 16:00 to 20:00 (an hour later for clock time in the UK for Summer time). I would say that this is less noticeable at the start and end of the season.

The best I could say given my experience is that during most of the season VHF Es occurs after about 10:00 and rarely after 20:00. Near the peak at the Summer Solstice Es can occur almost all day and most of the night. This is especially true towards polar regions (where it does not get dark at that time of year).

I recently saw a suggestion in a magazine that the second peak only occurs at higher ionisation levels, so for example, might occur on 6m but not on 4m when 4m is only slightly open. For a weak event it suggested that only the morning peak would occur. I see the point they are making, I just find that sometimes I only get the later one!

It is very difficult to be certain because on 6m and 4m there are many countries which do not have the bands, and there might be various phases which open into desert or ocean.

What about multi-hop Es ...
A glorious thing if you can find it. With Es being pretty rare and irregular, we all thought that multi-hop Es was more or less incredible when I was first licensed. Then came some terrible dips in the sun-spot cycle and it emerged that what we passed off as F-layer propagation now turns out to be multi-hop Es. Some of the distances can be phenomenal. Some research suggests that up to 5 hops can be involved.

 It is bound to be less prevalent as you go higher in frequency, as Es is less common. However, at 6m I have worked trans-Atlantic paths. On 4m I have been heard in Asia. I am hoping one day to work into central Asia and Japan, but those things have not occurred yet. It depends where your station is situated. You can always hope.

What about the strange openings I can hear ...
10m and 2m are world-wide amateur bands. Generally you do hear only amateur traffic on them. On 6m and 4m things are different. On 6m you can sometimes hear TV timebase signals, mostly from Russia. On 4m there are wideband FM broadcast stations from Russia, and all sorts of sounds and FM signals from countries which do not have amateur allocations there.

These are useful indications that the band is open to somewhere and perhaps the path will shorten or lengthen to bring in an amateur station.

Expect the unexpected ...
The band noise seems to fall when the band is open for Es. This can be a useful sign. Sadly it often signifies that the band is open for a single hop into somewhere with few amateurs (like the North Atlantic).

Thinking about this, and the fact that for 180 degrees round me I am surrounded by sea at the key 2000km distance, I called CQ beaming West and was answered by a station on the Azores Islands. If you look at the huge size of the Atlantic and the tiny relative size of the Azores group, you might be surprised that it was possible at all, never mind that a station would be there, tuned to 70MHz, at the time I was trying. But it happened.

Next stop, Madeira and Capo Verde? Please.

You just never know. Which is the joy of the thing.

And finally ...
Post your result to the cluster, please, so that we can see it all on DX Maps.

Have a happy Es season.