Monday, 20 January 2020

Japan on 2 metres, in easy steps

 Q. What does a man who likes following his summer sports (cycling, cricket), watch during the Winter?
A. Ski Sunday, of course.
==============================
SPOILER ALERT
All will be revealed ....
==================================
 
Here is a photo of last night's sunset, which has little particular significance to this tale, apart from signalling high barometric pressure and possible tropospheric lift conditions
Sunset at GM4FVM on 19 January 2020.
Last Saturday (11th January) was interesting. Not that I set out to work Japan on 2 metres. It all happened in nine small steps.

Step 1 - The erratic linear amplifier

My 70cms TE Systems 4452G has never quite lived up to the performance of my other two TE Systems amps. Theoretically capable of 175 watts it has never really delivered more than 130, though those 130 have done very well for me. I set it up and left it on the "do something about this later" list, thinking it needed tuned like it's 6m sister.
TE Systems linear at GM4FVM, plus sequencer, fans, fan controller and rat's nest of wires
Over the past few days it had become erratic, cutting out. So something had to be done now. Funny how things get put in the "do something about this later" list and stay there until they appear in the "do something about it now" list becase they have failed entirely. So the "do something about this later" list is really a "do nothing and wait" list.

Wiggling various cables revealed an erratic connection in an "Anderson Powerpole" plug and socket in the lead. Being an inhabitant of the European side of the Atlantic, Anderson Powerpoles came as a surprise to me. I had dabbled in electronics for over 50 years and never seen one before this linear arrived. Of course I had heard of them, and I had read of the idea that they were the perfect solution to every need and they never fail. Try as I might I could not save these ones, and they were consigned to the bin.
Cut-off power poles and their boot.
I cut off the shrunk-on boot and I could not find a way to tighten the crimp on the plugs, so I had to cut them off. Then it dawned on me that the boot had been hot. Was the linear running low output due to power starvation?
=========================
I AM GETTING THERE
Patience ...
=========================

Step 2 - Assuring the 70cms linear full power

As a bit of background I should say that this 70cms linear was bought from eBay second hand. It did seem rather cheap, and looking back in eBay records I discovered that the previous owner had bought it a few weeks earlier. This did not put me off, but it did make me wonder.

It had arrived with a few non-standard alterations. One was that it had an extended DC power lead, linked to the supplied power lead by the offending Anderson Powerpoles. The linear had Anderson Powerpoles fitted too and these were much heavier than the ones at the joint,. I now noticed that the extension cable was a bit thinner than the original. So did the lighter extension cable and lower rated connectors combine to reduce the voltage, limit the current, and hence the power, to the linear?

Once I connected the shorter original power cable direct to the PSU I got 150W output. Not a bad improvement. So I got out the mutlimeter and checked the output of the PSU on its "13.8V" fixed setting. Hmmm, 12 volts. Turning it to adjustable voltage and resetting - 13.8V produced 180W output! Tah dah!

Step 3 - Testing the linear at full power

The TE Systems has four fans on top added by me. I am paranoid you know. Two run during PTT, and two on a temperature controlled switch, allowing me to monitor the temperature. This trends up to about 32C before stabilising. Would it get too hot on 180W and 13.8V, compared to 130W and 12V? Quick test, no sign of that, in fact it seems cooler on 13.8V (the fans run from a different supply so they were not turning faster).

As is so often the case I could find nobody on 70cms to test with. However, I noticed from PSK reporter that Colin GM0HBK was receiving DL7APV on moonbounce. Maybe conditions to the moon would be good and I could get a real test of the amplifier there.

Up on moonbounce DL7APV was POUNDING in. I did not wish to bother him as he was working a station in China and I worked him before ...

Step 4 - Turn 2m to moonbounce while I am busy on 70cms.

No point being in the shack and not having both parts of the dual band antenna working. If I am pointing at the moon I usually turn both bands on and lsiten. Why not? You never know. While I am on 432, I tend to set the 2m radio to 144.120. Theoretically, 120 is a sort of "calling frequency" but it is little used for that.

Step 5 - If I hear somebody on 2m, I should work them.

Whilst fiddling around between three stations on 70cms who were supposed to be operating (though I could only hear APV) I noticed that S51ZO was really strong on 144.120. I checked and I had never worked him, so why not give that a try?

Really strong in this context means -20dB, and I was something similar with him. I only have 7 elements and no elevation, so any contact is a good one. Mind you, the story goes that if you can get to the moon and back you can work anywhere in the world, as the distance is much the same. That never works for me, as on 2m I had only worked Europe. I did wonder a bit, because I have worked USA on 70cms EME.

Step 6 - Let stations know you will QSL.

It is customary to exchange confirmation of moonbounce contacts on the WSJT EME website
 https://www.chris.org/cgi-bin/jt65emeA
Well, I do anyway, and it seems to be expected. Joze, S51ZO was there and keen to confirm that I would QSL direct. I would, after all he was a new contact for me.
===================================
 I AM NOT STRINGING THIS OUT
Nearly there
===================================

Step 7 - If you post, you will be pounced on

I mean this in the nicest possible way - if you let people know you are on EME, they will ask you for skeds. And this time Juu, JH0BBE asked me to try to work him on 144.131.

Now I have had JUU ask me for a sked before and it did not work. Me? Work Asia on 2m?

Being a polite and civilised person, and a model radio amateur (as you all know), I would not refuse his request. Of course I will try,

Step 8 - If it can happen, someday it will.

On the face of it, given the lower power most Japanese stations run, there should be a chance of me working them on EME. When I see a US station I have a pretty good idea that they will be running 1000 or 1500W, and they need to be very strong for me to try my 300-ish watts. That is running my amplifier absolutely flat out, something I rarely do. But with Juu running 500W there was a chance.

Then he posted that he was hearing me. Eh? So I persisted. And then I decoded his call. Could this be happening? I sat there and watched, yes watched, the tell-tale double lines of the shorthand message RRR as it trailed down my waterfall. No need to decode it, I saw and heard it. Wow!
2m EME at GM4FVM 11 January 2020.
Step 9 - the QSL card

Juu asked for a direct card, which was off at the Post Office the next working day. And Juu's card arrived with me in just over a week. Three cards in fact.

It might be my first JA in EME, in fact my first station outside Europe on EME, but it is first contact number 910 for him. He has 2m DXCC, and he has helped me to continent number 3.

My report from him was -26dB, effectively RST 0. He could not hear me, but the software could decode me. For me he was officially  -27dB, but I both saw and heard his RRR, so that must be RST 551. My noise level is very low.

Summary
I never set out to do that. I set out that day to fix the dodgy connection on the 70cms linear. I ended up working Japan on 2m.

There is a program on UK TV called "24 Hours in Police Custody". In it, real-life ne-er do wells, rapscallions and perps get questioned by the police while we all look on agog at the shocking nature of their crimes. The thing is --- it is real. They often say "I never meant it to happen. It started simple and then it all changed and go complicated. I was swept along on the tide of events.". Well, that is what happened to me.

Finale
The next day, peering again at 2m moon bounce, I saw this:-

200112_183900   144.120 Rx JT65   -25  2.5 1579 CQ S51ZO JN86                         f
200112_184000   144.120 Rx JT65   -27  2.7 1499 S51ZO ZL1HD RF82                      f
200112_184100   144.120 Rx JT65   -21  2.5 1580 ZL1HD S51ZO JN86 OOO                  f
200112_184200   144.120 Rx JT65   -21 -0.5 1501 RO
200112_184300   144.120 Rx JT65   -22  3.3 1582 RRR
200112_184400   144.120 Rx JT65   -22  3.6 1501 73
200112_184500   144.120 Rx JT65   -21  4.7 1583 73

That was both sides of an entire QSO between S71ZO and ZL1HD.

I have never heard a ZL before during my entire amateur radio career. And now I hear one via 2m moonbounce. What a square RF82 would be for me.

Sadly, I had left the rig running and it recorded that event. I could not try a QSO with ZL because I was not in the shack. I had gone to watch .... Ski Sunday.

73
Jim
GM4FVM

Friday, 10 January 2020

Lift conditions - at last

Dear all

After complaining about the superb tropo openings of 29 December missing me entirely, things got a bit better over the next ten days.

I should not feel hard-done-by any more, but of course I still do. Perhaps now I have less justification for feeling like that, but it won't stop me. I was born and raised in a section of society that felt that the world was against them, and I cannot shake that off just because it was never true. 

High pressure conditions brought some tropo on 1 January.
Contacts at GM4FVM on 144MHZ on 1 and 2 January2020.
I was pretty pleased with this, having missed out on the better opening a few days before. UT1FG/MM is an interesting contact as he chuggs around the North Sea. I can only work out his position when he gives a locator square while calling CQ on FT8. Sometimes he does and sometimes he doesn't. This time it was JO36, a square I do not often contact, it being entirely in the North Sea

I was even more pleased with the 70cms outcome
Contacts at GM4FVM on 432MHz on 1 and 2 January 2020.
Great to work Charly DF5VAE again, this time on 70cms for our fourth band. In fact I worked him twice on successive days. I am impressed by this performance given that I do not run high power on 70cms, have only a modest antenna, and I often go without contacts for days on that band.

Even more surprising was to work UT1FG/MM on 70cms. At first I was not clear what his locator square was - he might have moved since the 2m contact. As it turned out it was still the wet square JO36: I knew because he called CQ straight afterwards. It was a difficult QSO to complete - I am not sure what power or antennas he uses. But anyway I got it on the log book eventually.

Nice also to work DL7APV in JO62 again, and he provided the ODX for this event on 70cms, 1027km. By comparison on 2m, ODX was to SO3Z in JO82. At 1297km that hardly seems as much further than I might have expected. Mind you, on 70cms DL7APV has very large antennas.

For the two days, 70cm yielded 13 QSOs, 11 squares and 4 DXCC, while 2m accounted for 19 QSOs, 16 squares and 7 DXCC.

Quite possibly I was doing less well on 2m than I might have hoped because my LinearAmp Gemini 2 amplifier has been giving trouble. It was back with the makers for attention so for a while I was spending more time on 70cms than 2m. The resistors in the SWR protection circuit have been replaced. It is working again fine now, and I guess that is the problem solved. I have been pondering the possibility of upgrading the 2m linear but basically there is nothing wrong with this one.

After the 2m opening on 1 and 2 January, I turned my attention to the Quadrantid meteor shower and 6m. On 3 and 4 January I worked quite a few on 6m using MSK144 ...
Contacts at GM4FVM on 3 and 4 January 2020 on 50MHz meteor scatter.
A very nice set of contacts which proves how easy 6m meteor scatter really is. The stats bear this out, just 7 QSOs brought 7 squares and 5 DXCC. ODX was OH6WD in KP23 at 1756km.

By 5 January though the meteor scatter activity was declining, I could see those tell-tale signs that Winter Sporadic E (i.e. apparently "Es", but in the Winter) was back on the scene. You can tell when stations on meteor scatter have much longer reception periods than the usual ping on meteor scatter. This was the start of several days of Es, and when I eventually produced the map the data was so dense there was no room to add the callsigns.
Contacts at GM4FVM on 5 to 9 January 2020 on 6m Sporadic E.
On 5 January made just one Es contact, OZ5NJ, but on 6 January I made 14, reaching onto Italy, Sardinia, Spain, Switzerland, France and Romania. On 7 January I worked one station again (DL5WP), but on 8 January I worked 21, adding Slovenia, Poland, Croatia, Belgium and Austria. 9 January brought 8 QSOs adding Sweden, Estonia and Finland.

With the addition of a couple of tropo contacts that amounted to 45 QSOs with 35 squares and 18 DXCC. ODX was YO2LEA in KN06 at 1960km.

That was quite a spell. In my last posting I said that Winter Es keeps you on your toes because you never know when it will happen. Well here is the proof. There was no particular new ground broken, just a fascinating spell of operating over four days.

I heard nothing of Winter Es on 70MHz or 144MHz during these openings.

I suspect that is the end of Winter Es for this season for this season. Nobody really knows what causes it, though I do wonder about the fact that it occurs at the same time as peak Es conditions in the Southern Hemisphere. However, there is no known mechanism for that to work in the Northern Hemisphere, and the whole thing is a bit of a mystery. Still, all good fun.

From now until April I expect things to be a lot quieter. There may be a tropo opening. There may even be an aurora, the first in years. There may be more developments on HF as the sunspot cycle gradually starts to lift off. I doubt it though. I have plenty of projects to be getting on with. It was good though to have a good week's operating to fill my memory banks with material to keep me working.

73

Jim
GM4FVM

Tuesday, 31 December 2019

The closing days of 2019 and what a year it was???

Before reviewing the year in general, it is worth considering the last few days of it in more detail.

That strange phenomenon "Winter Es" made an appearance on 28 December. I first noticed that S52OR was coming in consistently on the 4m meteor scatter frequency. Unlike the usual pings, he was there for the full 15 seconds. I quickly went onto FT8 on 4m and 6m. There seemed to be some action on 2m, but not here at GM4FVM.
VHF contacts at GM4FVM on 28 December 2019
This is my activity map for 28 December (click to enlarge the images if you need to, as usual). The two UK stations were on 2m, the others on 4m and 6m. 15 QSOs in 7 DXCC, bringing a total of 12 squares. ODX was SP8ALT in KO11GG at 1697km. The Winter Es opening lasted 61 minutes here. I suppose in the great scheme of things that is not much of an opening, but it brought a bit of hope to a very quiet scene.

The thing about Winter Es is that you never know if it will happen on any specific day. It keeps you on your toes. I missed out on the 2m part. Grrr.

Another dramatic opening was the tropo event on 29 and 30 December, affecting 4m, 2m and 70cms. Except that from a GM4FVM point of view it hardly happened at all.
15 minutes of 70cms FT8 activity on PSK Reporter on the evening of 29 December.
You may notice from this chart that the event missed my part of Scotland entirely. The lonely pin over GM4FVM is just my alter ego, GM8JWG's short wave listener's posting. GM8JWG hearing GM4FVM does not really count as DX as they are both located in the same building.

The other remarkable thing about that slice of activity is that it is on 70cms. I thrash away on 70cms FT8 all year, and mostly it is a pointless exercise. There are contacts to be made, but nobody there to make them with. This clearly shows that many people have the ability to work on 70cms, but most don't do it.
The Hepburn tropo predictor shows the centre of the tropo over the Atlantic with sideshoots over Southern England and France. Although predicted to make a glancing blow over Southern Scotland we saw next to none of it.

All was not lost though, and in a brief opening I did work some DX on 29th.
Stations worked at GM4FVM on 144 and 432 MHz on 29 December 2019
PA7MM and G8SEI were on 70cms, the others on 2m. As things go, that would be a good haul for me, but this was a day when stations on Central England were working Poland and the Canary Islands on 2m. A lucky few in the Southern parts of Ireland and England were hearing Capo Verde.

Still I cannot complain, in just 11 hours and 22 minutes I worked 6 stations in 5 squares and 4 DXCC. ODX was the ever reliable Charly DF5VAE on 2m, JO46RK at 1001km.

I spent quite some time trying to reach Fidel from Castro, EA1HRR, to see if I could reach a new DXCC on 70cms. Fidel has given me 6m, 4m and my first EA on 2m, so it would have been fitting for him to be my first EA on 70cms. No sir. He could work stations in G-land but not me, sadly. 

The conditions continued on 30 December with G stations reaching all over Europe and I was on duty all day to work GW6TEO and GM4VVX. Both of those contacts were a real struggle but at 505km, GW6TEO probably had the choice of many more exotic stations to work than me.

I have been in touch by email with an amateur in the thick of it in IO82 square. He described to me the excitement of being in the middle of a huge opening. I am genuinely pleased for him. There is learning in this for me too. I have never been just beyond the edge of an opening before. Or, I probably have, but before PSK Reporter and DX Maps I never really knew what I was missing.

In the past I have described the odd feeling that during a DX tropo opening the "normal" tropo stations disappear. When I can work Poland or France the G stations in between seem to vanish. Well now I know what that feels like to disappear like that. While the G stations were working EA8 and SP, they vanished for me. The net result was that I could not hear the EA8s or SPs, nor could I hear anyone else. For hours on end I could hear nobody at all, on 2m or 70cms. Even if their beams are turned away from me, I can usually hear G stations off the back of their antennas. Not this time.

Enough whingeing. Sometimes you win some, sometimes you lose some. This time I lost. I will feel sorry for those just outside the tropo bubble next time I find myself inside it working tons of DX.

I will so.

I will share their pain even as I am living The High Life, and Living It Well (sorry, 1994 Scottish TV comedy series reference).

Honestly. I will share their agony.

I will.

Because they will be doing that for me right now.
=========================
It has been a busy year OK.

Apart entirely from the radio, the three cycling Grand Tours were all brilliant, and the even the cricket World Cup was interesting. No, maybe interesting is the wrong word for cricket, people usually say "absorbing" instead.

Plus by train I made it to Wuppertal with its strange upside-down wobbly monorail, and even to the 2000 year-old Roman amphitheatre in Nimes
Nimes: an ancient monument (and an old Roman building on the right too)
On the radio front there was the arrival of quite a lot of gear left to me by David GM4JJJ. Possessions are just that, and I would rather have had David still with us, but that was not to be. Excellent equipment it has proved to be too.

As for operations, the picture is of some things at FVM being the same, and some very different. The DXCC table of countries worked shows this:-
GM4FVM DXCC table extracted from Clublog
10m varies depending on whether I am using WSPR as normal, or sometimes FT8 which count as QSOs. The big drop in 6m DXCCx worked in 2019 is due to me only having a half wave vertical up, and trouble with my linear. When did I not have linear trouble? In 2018 it seems, but I must have been having trouble with a different linear then.

4m, 2m and 70cms are much as before, but 23cms is a new entry. I do not expect 23cms to provide much action in the next year but I am willing to be surprised. There is something to get sorted for 2020 - some more power on 23cms.

Also on the way is the return of a 6m beam. The new beam is past the design stage and it is now in the cutting metal phase. We shall see how that works in due course.

So an interesting year. Meteor scatter has not been very good. The Geminids in December seemed to be pretty poor. I am placing my hopes on the Quadrantids (or Bootids), this time due to peak on 3 to 4 January 2020. That leaves the meteor scatter diary free until April, but I shall strive for random contacts during the lull in showers.

The tropo opening of 29 and 30 December seems to be rumbling on still. There are suggestions that the barometric systems will continue to circulate nearby for about a week. As usual the Scottish weather is pretty variable and we need to see how this turns out.  It seems it was also affecting UK "Freeview" television signals in the 470 - 700MHz range, something that we do not see too often.
https://www.bbc.co.uk/news/technology-50945421

What does the future hold for this part of the world? Well, I received a parcel by Royal Mail today from Uxbridge near London. On the back was a UK customs declaration. Has Scotland already left the UK and nobody told me? Is this the present or is this for the future? Do I need a new callsign? No comment necessary or welcome on that debate, let us stick to radio here.

Ah well, the future will reveal itself when it is ready.

Have a merry Hogmanay and a great New Year.

Best wishes from GM4FVM

Tuesday, 17 December 2019

Moving forward with a plan... ?

We do not know what is around the next corner. Perhaps it is just as well.

I could worry about everything, or I could make some plans to move forward.

I guess I will do both. Anyway, the overall outcome will be the same - entropy and decay will win the argument in the long term.

When I was a part-time student long ago I went to evening lectures at the university for 8 years. Sometimes after a long day at work I fell asleep in the lectures. I left a long pen mark across my notes when that happened. I still managed to get qualified, but I am not sure how.

I have forgotten most of it. I do remember the economics lecturer telling us that the ideal savings profile across a lifetime is to start at zero and end at zero. We should have savings, in case of problems. But we arrive in this life with nothing, and we will leave with nothing. He could not see much point saving to build up money to leave to future generations. So he reckoned we should organise our lives to have no savings left at the point of death. He said that the issue for the later years of life should be about spending savings, not adding to them.

Maybe he was right. We do not know when our key will fall silent, so why keep a large sum to be left at that time? OK, save some, but spend a little now too, before it is too late.

Well, that is my story anyway. A reason not to sit and worry and a reason to spend a little now to make life more pleasurable.

For some that means changing a perfectly good radio for an £8000 one on which to work the same stations. Not for me. Time to expand the 1296MHz set-up, and time to get the antennas better organised in the hope of working something new.

So it is that I find I need more storage. My linears are perched on top of my shelving - not good. Where can I fit in a new linear?

I have been busy obtaining more shelving. Not your cheap and tatty stuff, but from a high-end supplier called Ikea. All hand made (hand made in the hall outside the shack and carried in). And another free little quad-key screw driver to add to my collection, courtesy of Ikea.

And not just Ikea, but Ikea's kids range. After all, amateur radio is child's play. I already have 4 sets of their children's range "Trofast", an adjustable sets of boxes meant for toys and therefore holding my toys. Or my components, plugs and sockets.  But now Trofast has a fancy option, finished in white rather than plain wood finish. The other wood finished stuff is hidden away in cupboards, but the new white one can go on view in the shack. Wow! Premium quality.
Ikea Children's Trofast storage unit in white at GM4FVM
If this looks a bit odd, there is only one of them. It looks like two, but the cupboard on the left which contains the older Trofasts has mirror sliding doors. The previous owner of this house used this room as her bedroom, and she had one entire wall covered in MirrorRobes. It has never been clear to me why she wanted to cover an entire bedroom wall in mirrors, but there you go (Jim, really). When we made the room smaller it made sense to keep the cupboard doors, so one side of my shack is mirrors. Now I can watch myself operate. How strange. Why would I want to do that?

But enough of all this. Also left over by the previous owner of this house is the television shelf above the new unit. This was screwed to the wall, and I left it. Now it has my 70cm TE Systems linear amplifier on it. Also there is the temperature controlled fan unit for the linear, the 70cms sequencer and a bias-tee. The Trofast fits below and the 23cms linear will go in there, along with another sequencer and bias-tee. Then there will be the power supplies lower down.

There is also a box in the Trofast for all those cables I never quite know where to store. The ones I need at short notice, but not very often. Patch leads, for example. I discovered that if I put the box at the top of the unit I could save a shelf. I am getting very organised.

This is the point here. I have actually given some thought to where to put something, before the something arrived. It helps that my economics lecturer from 40 years ago gave me authority to spend my savings on this unit. But it is necessary, and is a good way to spend not very much money. The basic frame is £30, and the shelves and boxes are extra.

Come to think of it, he would have called this investment, so it is even more easily justifiable.

The 23cms linear is under construction but I am not sure when it will be ready.

Another investment of my savings is in an experimental antenna for 4m and 6m. I have two perfectly good PowAbeams for 4m and 6m, but that is the problem. There are two of them. For the winter I have put up my old Vine 4m/6m dual bander which is better then as it is only a single antenna, but not very good as it has a single feed. Single feed does not suit my multi-band operating method. And anyway, I like my antennas to be connected to my rigs by co-ax.

The Vine uses the sleeve method of driving the 4m beam. Call me old fashioned, but I prefer a bit of wire to my antennas. Erm, well the sleeve method is old fashioned too, but ... right, ... when I think about it, I have no good reason for not liking the sleeve method, but I just don't like it.

To get round my issues with single feed in the past I built a diplexer for the Vine, which meant that I could use 4m and 6m simultaneously. I was never happy with that either. At this point in my life I reckon it is time to be a bit happier.

Rig - coax - antenna, that is my preferred route.

So I am also gambling a bit of my savings on having an experimental calculation done for a 3/4 element dual band antenna for 6 and 4 metres. This would have two separate feeds and work as separate beams on a single boom. All the commercial ones of my size  (3m boom max) are single feed and have all the same issues as the Vine. My idea is being modelled now so we will see if it works without sacrificing too much.

So there is actually a bit of planning going on here. Life planning, to free up some savings. Room planning, to make some space. And antenna planning, to model something a wee bit different and hopefully more efficient.

Funny, I am not noted for planning.

73
Jim
GM4FVM

Wednesday, 4 December 2019

Just a bit of fun

I think this hobby should be fun. It should not be all about understanding Faraday Rotation or precision frequency measurement. Sometimes we should just leave the work to one side and do something for ourselves.

The thing I left aside is a posting on this blog about how to tell the difference between the various VHF propagation methods. Stirring stuff. Like many of my postings it is far too long, too wordy, too ... too much like hard work really. They must be a right pain to read.

For a few days the barometric pressure has been rising as an anticyclone passes across Britain roughly from North West to South East.
There was a weather system across Scotland which was likely to spoil things a bit, but for about 5 days the Hepburn Tropo Predictions (see link on sidebar) have been suggesting that yesterday, Tuesday 3 December 2019, would be the day when VHF and UHF conditions might improve.

So I set Tuesday 3 December 2019 aside as a day to work a few stations and see how I got on.

I really enjoyed it. Good fun.

The significance of Tuesday is that it is the "Activity Contest" day in Europe. Well, it was, until we started having 6m and 4m activity days on Thursdays, which is a good idea but does make it all more complex. This was done because, despite the constant nagging from contesters, the national radio societies were unable to fit six Tuesdays into every month. Those national societies - what good are they if they cannot regulate the number of Tuesdays in the month.

First Tuesday in the month is 2m activity contest day. Now, as is well known, I do not enter contests but I do give away points. So the plan for this Tuesday was to operate as much DX as I could if conditions were good during the day, and then help out in the contest for even more DX during contest hours.

The RSGB National Activity contests run from 20:00 to 22:30 UTC for all modes, with earlier contests from 19:00 to 19:55 for FM and data modes. However, as conditions were looking up, I decided to switch to my favourite contest, the Nordic Activity Contest (NAC), which runs from 18:00 to 22:00 UTC on Wintertime Tuesdays (switching by an hour during daylight saving time).

For this contest I decided to stick to FT8. As many of the NAC stations use FT8 in its European contest mode I can get a useful updated conest log on WSJT-X which saves me trouble checking for those stations I have already worked.
Contest log with WSJT-X in the "EU VHF Contest Special Operating Activity" mode
Interestingly the latest entry in the log is at the top numbered one, whereas the serial numbers (which I have not managed to capture in the above screen grab) go the other way.

The signal reports used in the European contest mode are "59" type RS strength reports with a serial number, rather than the conventional FT8 "dB S/N relative to the noise in the SSB filter" type reports. If presented with a Euro contest type report WSJT-X will switch over to that style until you dive into the settings and turn it off. Using two different styles of report in two contests running at the same time causes endless confusion to those in the RSGB data contests which do not use serial numbers or the Euro contest system. It all adds to the fun. 

I like the NAC because of its informality. It also helps that the stations involved are usually at a handy distance if conditions are good. Often I can use meteor scatter, but perhaps this time tropo would be good as the high pressure seemed to be perfectly placed. Tropo openings are often best just as the high pressure is subsiding, which it obligingly did.

As usual, click on the images if you wish to enlarge them.
Stations worked at GM4FVM on 144MHZ on 3 December 2019

As the NAC on the first Tuesday of the month is for 2m I did concentrate on that band, but I did some 70cms too. You don't need a contest to make UHF DX interesting, but sometimes it helps.
Stations worked at GM4FVM on 432MHz on 3 December 2019
Before the NAC began I worked 18 stations. On 144MHz it was 14 stations in 8 DXCC, on 432MHz it was 4 stations in 2 DXCC. I only worked France on 432MHz (twice), the others on 144MHz being G, GM, GW, GI, OZ, PA, DL and ON. ON4POO kicked the whole thing off, as he so often does. The two stations in France were F5APQ and F4HRD both in JO00, which isn't bad on 70cms at about 600km from here. I bet I could have worked more stations on 70cms if there had been more around, and of course during the 2m contest the 70cms activity fell (but did not stop!).

During the NAC I worked 10 stations in OZ, LA, and SM of course, plus PA0O as yet another participant in NAC. I was only on for about 2 hours of the contest as I had to go and watch "Masterchef The Professionals" on the television. We have to keep it fun you know.

After the contest I worked 4 stations on 2m (SM and OZ) and then one on 70cms (OZ).

Grand total
For 2m, 30 QSOs over 13 hours and 18 minutes, 18 squares, 10 DXCC, ODX SM7EGM in JO65 at 988km, and
For 70cm, 5 QSOs over 12 hours and 4 minutes, 3 squares, 3 DXCC, ODX OZ2ND in JO46 at 690km.

I am not sure if 70cms contacts count double the distance but they should. Two other contacts that got away were both GI6ATZ, heard on 70cm and 23cms. Either would have been an interesting QSO, and on 23cms a new country for me. However, as the contest was underway I left him to it.

So, I did not enter another contest. I just did some operating. Including a contest is easy when you do not have the keep any records for your entry and it does not matter much if you slope off to watch the telly for a couple of hours.

There was nothing special about 3 December 2019. It was just a chance to work a bit of tropo with the activity level which comes with the contest.

Along the way I did nip outside and change over my 432MHz masthead preamp. I have done this several times over the past 6 months and I have honed the time down from an hour to just 27 minutes. It is getting like a Formula 1 pit stop. I need to work out what is happening. Perhaps that will not be so much fun as a day's operating.

73

Jim
GM4FVM
  






Friday, 15 November 2019

FT8 and 100hz ripple, a strange one for me

The general idea behind sound-card based data modes is that you transmit some tones from your computer using a transceiver, and then use the computer to decode the tones created by others which you receive in reply.

This makes things pretty easy technically. You need steady tones, stable radios and well adjusted sound levels. Modern equipment available to radio amateurs make the whole process fairly simple and reliable. Having said that, rather than amateur radio gear, the tones come from your computer sound card, and who knows about the purity or fidelity of that?

Neil, G4DBN, gave a useful talk on FT8 at the 2018 RSGB Convention. This was recorded by the RSGB and you can find it on YouTube here. If you use data modes I really do encourage you to take the time to watch Neil's presentation.

Neil suggests that it is a good idea to monitor your signal to make sure there is nothing odd going on.

Now, as it all (i.e. all those modes including FT8) relies on everybody being in the same receive and transmit filter bandwidths, the potential for an unwanted signal getting through are quite high. If you are transmitting a 500hz tone, you might generate a 1500hz harmonic, and as that is within a typical 2.7kHz or so filter, you will transmit that and it will be heard by everyone.

Luckily, that type of harmonic is not so common and you can solve it by raising your transmit frequency to 1500hz, whereupon that harmonic becomes 4500hz and is way outside the filter. It would still be there but it would never get transmitted and never get heard. If we ever go beyond the standard SSB-type filter to using really wideband signals then we will have to find a better solution than that, but then we will probably have such superb modes then that we won't care.

Returning to the real world, I thought it best to keep monitoring my digital signals and I still check from time to time. I was thinking that I might find a harmonic of the type I describe above, maybe capable of being resolved by altering the drive at some stage or other.

Oh dear. This latest test was not what I expected to see...
GM4FVM monitoring his own FT8 signal producing multiple decodes (click to enlarge).
In this instance you can see two parallel signals on the wide graph, each 100hz away from the main signal. Both of them are decoding and the worst is showing up as -30dB below the main signal. You can just about make out another pair 100hz further out.

The set-up I was using was transmitting into a dummy load on an IC-7100, receiving on an IC-9700. I could juggle it about, tx on the IC-9700, rx on the IC-7100, or between two IC-7100s, on 70cm, or 2m, and then using an IC-7300 and the 7100s, on 70MHz or 50MHz bands the results were broadly the same.

These are not harmonics of the wanted signals. They have nothing to do with over-modulating using the wanted signal. These are extra modulation products introduced either in the computer sound card or the transmitter.

Something was allowing 100hz into my system. The FT8 signal was then effectively being modulated at 100hz in what I imagine to be an AM-style (unwanted) method. The harmonics of the unwanted 100hz signal are producing mirror images 100hz away. All of this is at far higher levels of RF output than I consider to be acceptable. -30dB is FAR too strong for an in-band unwanted signal for me. In this case it is not just in-band, it is in-filter (if such a compound word exists). I was generating something that others could hear, and those others might be listening for weak signals and not liking what I was doing.

I consulted various people about how important this is and the consensus of opinion was that "it depends". "It isn't good but did anyone complain?" "Is it somehow appearing in the receiver and you am not transmitting it at all?" And several who have heard me say that there is nothing untoward visible or audible on my signal. This last comment is very comforting, but of course it only adds to my knowledge of my signal if they are hearing me 30dB above their threshold - if I am weaker than that they would not hear or see the unwanted signals. However, say during a Sporadic E opening when signals are strong, someone else might hear them loud and (not) clear.

Before going too far I checked to see that this was not an artifact turning up in the receiver. Using four radios, both ways, it was still there. And it was not on most signals received from other amateurs. The theory that this was in my transmitted signal was tested later and it certainly does not seem to be the receivers at fault.

Nevertheless, some received signals do have that effect on them and it was pretty easy to see that it was not introduced at my end. I have been on the receiving end of these hums being transmitted by others, but equally strong signals received at the same time are clean. Here is one from a station in Hungary ...
A certain HA station as decoded on 70MHz by GM4FVM in 2019
Note that as this guy faded out as shown by the trace at 13:15:30, the two unwanted signals faded not long before the main one, meaning that they were strong in relation to it. -18dB according to WSJT that day. This evidence made me more certain that I needed to eliminate my unwanted signals. Although some advice was that "if no locals could hear it then it didn't matter", I know that I can see such things on DX stations who are loud. And anyway, I do not want to radiate unwanted signals.

And these things can get worse. The evidence I produced suggested it changed depending on the radio in use and maybe just over time. Here is the worst I saw me manage, with 6 of my traces which were all decoded..
GM4FVM and his unwated FT8 friends captured at their worst by ... GM4FVM
In this case the strengths recorded for the unwanted signals relative to the wanted one by WSJT were -21, -29, -34, -42 and -43. This translates to the strongest unwanted one showing up as a signal of +01dB. As the wanted signal was +19, that means that during a Sporadic E opening similar to the one I saw the HA station, I would decode 3 of his traces and he would decode 6 of mine.

It just isn't good enough. Something must be done.

It does not really matter to me that other stations are doing it too, nor that no locals are complaining (there are no locals to complain anyway). I just had to clean up my signal.

Lacking any calibrated way to measure this, and recognising that some oddities might remain and pass through my filters, the target for fixing it was no decodable traces here apart from the wanted one. That suggests better than -43dB. Further, I wanted to get to no multiple traces visible at all, decodable or not, which looks like -50dB or more.

"ALARP" they called it during my time working with the railway industry. Any unwanted thing not capable of full control should be "as low as reasonably possible". Maybe I could not reach perfection, but I should try.

Turning back to G4DBN's RSGB lecture he quite correctly states that this type of effect is usually caused by 100hz ripple from switch-mode power supplies (SM-PSUs). It is well known that SM-PSUs can produce ripple on the DC output at twice the input AC frequency. Thus in parts of the world with 60hz mains supply this presumably causes traces with 120hz spacings.

My first line of thinking was that the station SM-PSUs must be generating 100hz ripple and that is getting into the radios. I changed all of the main SM-PSUs for analogue ones. There are two PSUs for the main rigs, one for the ancillaries (SWR meter, network radio,  Hy-Gain rotator controller ...) and one for the 70cms linear amplifier. No change. So they are in the clear. Despite this finding, I changed these around several times because I felt sure the fault lay there. No, it didn't.

Second were SM-PSUs which are not directly connected to the radios and are not what you would call "amateur grade" kit. Shop bought things. An early target was the computer, where any ripple reaching the sound card would explain the multiple traces. I changed the computer, but this made no difference. Then there were the computer displays, the supply for a multi-socket USB 3.0 outboard hub and finally one that produces 20 volts for the SPID rotator and 5V for the GPS standard. Nope, nothing.

By the end of this second phase I was beginning to think that the ripple must be generated somewhere else and be getting back down the mains into the equipment. This seemed highly unlikely. The whole idea of an SM-PSU is that it chops up the mains, generates higher frequency AC, and processes that. How 100hz hum would pass through  that I have no idea. For sure, SM-PSUs can generate their own 100hz hum, but can they allow 100hz hum coming down the mains to pass through?

However unlikely something is, if you have eliminated all the likely options, the unlikely ones have to be checked out. Sherlock would have loved me.

By this stage I had checked all the likely and all the unlikely options and nothing was the culprit. I still thought this must be something wrong with the FT8 signal going into the radio.

I should have realised sooner. The audio input graphical display on the IC-9700 and IC-7300 both showed clean audio coming out of the computer into the radios. This ripple had to be getting into the radios by some other means, but the penny had not dropped with me yet. That was a result I dismissed, and thus overlooked a clue.

Phase three had to be more radical. Even while I ignored a clue that proved it, I was beginning to think that this was getting into the radios by some odd means. If it was possible that this effect was not generated or passing through the computer then just monitoring a plain carrier would show no multiple traces. How could it? A plain carrier is unlikely to be modulated by 100hz hum coming from a computer which is turned off and disconnected.

So stage three saw one radio transmit a single carrier (CW key down or RTTY with no modulation), into a dummy load which was monitored by an SDR receiver with the trace observed on the waterfall. Both radios were powered from separate linear PSUs and entirely separate on both the DC and RF sides. Everything else was turned off and unplugged at the mains. Sure enough no multiple images. But then as I gradually connected various parts of the shack and powered them at the mains (there are three separate mains circuits), look what I saw ...
Tah-dah! The effect as seen on an otherwise unmodulated carrier.
When I connected the third mains circuit multiple traces appeared. In fact, I could toggle them on and off.

It took a while for this to make sense. Somehow a radio sending plain carrier and a receiver receiving it were producing or detecting 100hz modulation from some device not connected to them. The only obvious point of contact was the mains and that did not seem like a likely route (though possible). This had nothing to do with sound cards or FT8, though that was how I first noticed it. My computer was disconnected the whole time during phase three testing.

On then to determine which item on that circuit could be doing this. Obviously it must be ... nope, nothing obvious was doing it. The only thing left is the shack light, a fluorescent anglepoise which appears in my QRZ shack photo. As early mains powered LED lights were (radio) noisy I used a U-shaped fluorescent when the shack was built, and later replaced it was an identical one when the base broke. Could this be the cause? Surely not ...
Effect of light on and off as seen on the IC-9700 waterfall (click to enlarge if necessary).
Yes, the shack light was doing the damage. I will spare you the rest of the investigation. I tested with a reasonably close station on FT8 showed that with the light turned off they were seeing no sign of multiple traces. No amount of testing on my part showed any effect on received signals, so I am pretty sure (but not absolutely certain) that these multiple traces were generated on transmit  only. On testing on FT8, with any combination of radio (IC-7300, IC-9700 and two IC-7100s), turning the light on and off produced and removed the multiple traces. With the light off there were NO extra traces here, decoded or otherwise, visible or even partly visible, other than the main one.

The culprit
Gradually turning on the other SM-PSUs there were some slight bumps at 100hz intervals visible on the SDR waterfalls. They seemed to be -50dB or lower as I reached full operation. None of these were visible on the FT8 waterfall. I suppose these are the residual products of the switch mode process and I shall probably have to accept that. Some things, like computers and their display screens, would be hard to convert to analogue PSUs. I have to accept these unwanted outputs as ALARP, as low as I can make them. They have not gone away though, and will still be heard if my signal is very strong. I will return to the task of making them weaker later.

So the obvious thing to do is to turn off the shack anglepoise lamp. OK. I bought a cheap (£6) LED light with a flexible mount. This runs on 5 volts which is supplied by my (now tested) auxiliary PSU for the SPID rotator and the GPS receiver. So that is it sorted.

Or is it?

I am a radio amateur. I cannot just turn off the light without some investigation of how four separate radios managed to produce unwanted products without some explanation. How did it happen?

Also, as a radio amateur I am used to chasing round RF interference, clamping ferrites all over the place. And ferrites really do work very well against RF interference. But I am no expert on 100hz. I have read up that "electronic ballasts" on fluorescent lights, which have largely replaced the "electric" ballasts and starters, can indeed generate 100hz ripple. But how does this get into my radios?
The ballast for the lamp was held in a plastic box which broke up when opened to reveal this




Searching the Internet for the ballast using the reference number finds the manufacturer and the product name but anything else comes up as "404 error, page not found". I suspect that the BS EN standard referred to relates to double insulated (non-grounded) power supplies. Anyway I cannot get into the ballast itself and I only have generic circuit diagrams to work out what it is. Whilst it certainly might produce 100hz ripple, the means of transmission remains unclear to me.


The only suggestion I can put forward is that somehow this hum is being transmitted inductively. My set-up has lots of potential for hum loops. The radios are all grounded in multiple ways which are hard to disentangle - via the linears, at the power supplies, via the computer, via the SWR meter. And then the computer and the SWR meter are grounded together via the computer cables anyway ... and so it goes on. There is a rat's nest of DC wiring to provide lots of scope to pick up some low frequency energy and share it around via various routes with different impedances. Then again it might simply be passing through the mains (though I cannot really see how).

Even if that is the case, how can it be getting into the rigs? All four rigs in fact? I cannot test removing the DC supply cable, but I did remove the USB lead and the GPS frequency standard for the IC-9700. It cannot be getting down the coax, surely.

I am left with the impression that the lamp is leaking 100hz ripple down its mains lead (not grounded of course), and then inducing a similar ripple in the radio DC leads, or in the other DC connections and thus linking indirectly to the radio DC leads. In then gets inside the radios where it must be doing some mischief. How that modulation occurs I have no idea.

The inevitable consequence of all this is that there must a be a lot of energy coming out of the lamp down the mains cable, which also seems intuitively wrong. But then, touching the lamp holders of my bedside lamp in the days of coiled fluorsecents allowed me to feel the 100hz ripple via my skin. Those lamp ballasts must be a big inductive load.

Anyway, it has gone now. Banished from the house into the garage where it can do no harm. I did try it on a different circuit in the house but the effect was the same. As I cannot be in the garage and the shack the same time I doubt if it will cause any harm out there.

As for the future, there are lots of "mains conditioner" type multi-socket boards designed to cope with this type of thing. They are mostly aimed at musicians using amplifiers during stage shows. The drawback is that they generally have no technical specifications worth the title. They claim to stop mains hum, but do they? Even then, they will not stop anything generated in the PSU and passed on down the DC line into the radio, though they would stop anything radiating through the mains (if they work at all, that is).

I am left feeling uncomfortable. After 10 days of heaving about power supplies and digging under the bench I have an answer to "what" but no answer to "why". The lamp and the immediate effects are gone, but my equipment has been shown to be susceptible to a form of interference against which I have no real defence.

The inquiring mind is never satisfied.

73

Jim

GM4FVM



Thursday, 7 November 2019

Round the microwave table and more doubts about radio.

I feel like a kid explaining why he has been late for school.

I missed the National Ham Rally as I was away. I was also away for the Fog of the Tyne Rally. I missed the Galashiels Rally because my car was off the road for a week to be fitted with a £900 towbar. A £900 towbar? That is new rig money for something used to haul grass cuttings to the local dump.

I had no excuse when it came to the Scottish Microwave Round Table last weekend (apart from being broke after spending £900 on a towbar).






Heather, G0HMO, giving her talk on SDRs for portable microwave operation
I took the train to Burntisland, and the Museum of Communication is a short walk from the station there. There were 55 people there and it was great to meet Roger GM4PMK, Peter GM8GAX, Andy GM7GDE, Gordon GI6ATZ, Gordon G8PNN, Brian G8KPD, Eddie G0EHV, Norman G3ZWR, Jon GM4JTJ, Geoffrey GI0GDP, Barry GM4TOE, and Tom GM8MJV. Sorry if I missed anyone out of that list and I spoke to several more who I cannot recall right now. There was a lot going on.

In fact, despite the list people I did talk to, there were several more I hoped to meet but who escaped me as I circulated around.

It was a pleasure to receive my latest batch of QSL cards. Andy, GM7GDE, who is the RSGB QSL Bureau sub-manager for my callsign, had gone to the trouble of checking who would be at the meeting and bringing along their cards to save postage and time.

Being the sub-manager cannot be an easy job, and adding this personal element to his already excellent service was really appreciated. Thanks Andy.

The first talk was about Microwave EME. I have dabbled with moonbounce on VHF and UHF, but never on microwaves, so that was interesting.

Then we heard from Sam, G4DDK, about the technical aspects of the Icom IC-9700. Sam has written the review for practical wireless. I provided a link to Sam's article in my non-technical review on this blog here. Various things had changed since the review was written.

It was interesting to hear that some 9700 owners have still felt it is worth fitting an internal modification to the 9700 to give even more frequency accuracy than the 10MHz reference method. This involves swamping the 9700 master oscillator with a board soldered over the oscillator's shielding box. So although it does involve delving into the radio, no actual soldering of wires is needed as far as I can see. The replacement board couples inductively to the existing circuit and overrides the on-board master oscillator with a GPS or similar one mounted (presumably) outside the case. So far I find the 10MHz reference input to be fine for my purposes. So far anyway.

When prompted with a question about the single PTT output, Sam said that someone makes a CI-V operated outboard switching device, but he did not say who. I cannot find any reference to this item being on sale. Someone in the audience suggested using the DC pre-amp bias as a switch but I doubt if this will work as they are all on so that you can receive on two bands at once. I should check if they all go off on transmit or just the one in use for transmit at the time. If that did work, I would need to sequence all my preamps together on the PTT line.Also, can my sequencer supply enough current for all three pre-amps? Probably, yes, but I need to check. I would also need 6 bias-tees, two for each band, or do some surgery inside the case to reduce that to three.

The lunch interval provided a good opportunity for networking.

After that GM8IEM talked about constructing a 13cm home station around the Kuhne transverter. This was interesting, though 13cms is a bit far for me to think about when I am only just starting on 23cms.

Finally Heather, M0HMO, rounded things off by talking about SDRs and software for portable microwave operation. The idea was that a movement could emerge to provide a route into microwaves for new operators by utilising the latest SDR technology. This became a bit complex and I got left behind at times as I tried to interpret the jargon and initials in use. However, I got the gist of it and it seems like a good idea. I doubt if I will be mountain-topping soon though.

Neil, G4BDN, was presented with the constructors prize. The quality of his work is astoundingly good.

I also bought something at one of the sales stalls - an RF transfer relay. This is a possible solution to switching a linear amplifier I plan to use on 23cms. I say plan, but I have not decided which way to go on this project. Bert Modderman, PE1RKI, (site here), makes an interesting range of amplifiers, some of which might suit my needs.

Bert specifically states that you should not use transfer relays with his amplifiers. This is because they usually connect the input to the output of the linear on receive, opening the door to all sorts of problems.

Despite Bert's comments I still bought this one.
The diagram shows J1 and J2, plus J3 and J4, normally open as you would expect, but only J2 to J4 normally closed. So J1 and J3 are always open and I can connect my linear there and activating the relay will bring it into circuit. Otherwise that diagram suggests that the linear will be isolated and received signals can pass between J2 and J4 when not energised.

Well, so it says on the box, and checking it out with a multimeter suggests it should work. This was on sale at a good price for a transfer relay, but still rather expensive for me. I didn't have the money on me and I had to post a cheque afterwards to GM8GAX. Thanks Peter. I didn't have the cash due to spending £900 on a towbar, not that I am obsessed or neurotic about that. Oh no, I have forgotten all about that. Forgive and forget, I say.

This particular transfer relay came from a clearance sale of more items from David, the late GM4JJJ, so I guess he had the same idea as I did. I hope so anyway.

VK4GHZ's posting sets this out better than I could: here  http://vk4ghz.com/transfer-relays/

After reading VK4GHZ's posting I had been looking for one of these rather rare variants for some time. As I pondered it at the sale table, some helpful Microwaver pointed out that the next stand had a transfer relay for half the price. When I explained the unusual configuration of this one he looked blankly at me. The other one might be half the price, but it is not suitable for my plan.

But I don't have a proper plan for more power on 23cms. I have the rig, coax, preamp, sequencer, bias tee, antenna  and now the relay, but not the power amplifier. I am not convinced that the Bert Modderman route is the right way for me to go.

Here is the history for me. On every band I now use I have gone in barefoot or with low-ish power. Then after a while I have bought a bigger amplifier and in every case it would have been cheaper and easier to get the larger amplifier at the start.

However, I live in this twilight world of love/hate for radio. Every so often I want to go QRT and take up quilting. Or follow in my Granny's footsteps and try crochet. Making blankets is an Edgar tradition and radio isn't.
======================
I enjoyed the Scottish Microwave Round Table, and it was great to meet so many friendly and helpful people. I should be content but I am not. I cannot just throw money at a big linear for a band I hardly know. It might be a mistake not to buy the biggest boots I can find, but comfort counts in the boot world too.

I might be more comfortable with a small linear and make the same mistake as before. At least that will be simpler for me if I decide in a fit of pique to go QRT and adopt bear stuffing instead.

That is making stuffed toy bears, by the way.

Anyway, even if I do get into sewing and stuffing, I will always have the right transfer relay.

73
Jim
GM4FVM