WSPRlite Becomes Even Better

An awful lot of people are now using WSPRlite, if the number of 200mW stations evident on the bands is anything to go by.

Recently, SOTABEAMS has added some very nice and very easy-to-use analysis tools that make DXPlorer, the associated webware, even more useful and powerful than it was at its launch.

Over the past few days, I ran my vertical delta loop at 200mW, comparing with a very efficient station - a 52 foot dipole at 25 feet up - in Northern Ireland.

My delta, basking in the glorious late May sunshine

Here, firstly, is the plot of distances reached:

Now, the excellent performance of these two systems shouldn't be underestimated.  Here's a comparison with a station in England, who has until recently been my reference station for being one of the top performers (a horizontal loop).  All other stations I've compared with are either much the same as this plot, or the other stations are much worse:

Now, the GI station comes in on distances at what we can say is an identical performance to my station.  However, the recent addition of simultaneous spot analysis on DXPlorer reveals a wealth of new information.

In particular, it shows that, whilst the GI station is reaching the same distances, he does so, for the most part, with a significantly worse signal than mine.  All spots to the right of 0dB (positive numbers) were stronger from my delta than the GI's 52 foot dipole.  That's very useful information.

The outliers are largely irrelevant, being transient effects of QRM that suppressed the reception of one signal over another.

So, this little tool, costing merely £60, plus an annual premium mode fee of £20 after the first year, really does pay for itself in the sheer amount of valuable data analysis it performs with ease.  It shouldn't be underestimated, because this is the first time in amateur radio's history that an entirely objective, human-free comparison of antenna systems has become available to all of us.

I just wish the absolute power output of each WSPRlite could be as readily confirmed as accurate.  One former electronics industry expert told me his 200mW was closer to 180mW.  I think, somehow, that unknown power output has to be addressed by some means or another.

RFI - And how your station may be suffering.

Some months ago, I came to understand how my rural, very low noise level is the explanation for why, over all the time I've been operating, I almost always give out a signal report that's better than mine.  This, despite having a very efficient station that uses no ATU on most days, and an almost unique QTH setting on a copper mine.

I'm not the sort to be in some form of competition on signal reports, but I do like to understand how things work.

I also figured out last year that a small 60W testbed solar PV system here produces a reasonable amount of broadband hash (RFI).  To the ear, on most bands from 12m and up, the hash is certainly detectable, but doesn't sound that bad.  The S-meter, meanwhile, doesn't show anything on my FT-450.

Now, 50% of the world's population, and probably a lot more of its ham population, lives in highly urbanised settings.  Most of that population will be suffering RFI to some degree or another.

The effect of even modest RFI is quite remarkable.  Here is a JT65 trace (24MHz) that ran with the solar PV system on (lower half), and then with it turned off (upper half.)  The signal-to-noise ratio clearly collapses catastrophically with the solar PV on, because the signal strength remains unchanged, whilst the noise has increased markedly.

I think you can tell where the PV system was turned off...

So, even if your S-meter shows nothing much, and your ears aren't buzzing with RFI, your station may nevertheless be suffering quite severely from the cumulative effects of urban hash.

What you can do about it is, of course, rather limited.  My approach has always been to invest as little as practicable in a home-based station, and always keep practised in the art of rapid-deployment portable operation.  That way, when your neighbour installs LED lights or a full PV system, you can just shrug your shoulders, not get too upset, and continue working, unaffected, out in the great outdoors. 

Reflections on a Radio Club

A few weeks ago, I decided I really should support one of my local ham radio clubs, and attend a meeting.

Partly, this was guilt-induced over the fact one of the club's members helped one of my children learn the Foundation syllabus.  It was also the feeling that, if we all didn't make an effort to attend, there wouldn't be a club, and the hobby would suffer.

I have to be straightforward and say that I didn't like many of the people that attended.  A more-than-typical proportion of the club were super-morbidly obese, and one wondered whether they ever got up from behind their radios of a day. 

JT65 you say?  Pah!  We never had any use for that in my day.  Bla, bla, bla...

But for the most part, the club was made up of those who had not only retired but were well into their sunset years.  The whole thing felt superficially like an evening event at an old people's care home.

Inevitably, there was more than a hint of stubbornness amongst some of the members.  The kind of stubbornness that comes with having been part of the furniture for decades, finding comfort in the unchanging, and the gradual loss of one's ability to cope with the real world. 

Also lurking in the background were those obsessives who make up the contesting brigade.  Everything except marking endless callsigns in a contest log is meaningless to the contester.  So I didn't even bother talking to them (they were, anyway, not interested in talking.)

Someone produced a rig - the kind of rig stubborn old men like to espouse as the 'best thing ever made'.  In this club's case, that was a 30+ year old transceiver that filled a desk - but that nobody could figure out how to get sound into headphones from!  Nobody bothered using it, anyway.

Whilst there were some very capable CW operators amongst the crowd, none of them seemed to have taken up any of the plethora digital modes that now dominate many of the bands. This is another generational thing, because computers hitched to rigs appeal to younger hams.  It's too much like newfangled technology to the elders.

Regrettably, after only two attendances, I found the whole thing highly unattractive.  It's easy to see why youngsters and females wouldn't even contemplate throwing themselves amongst that kind of crowd.

When I say I'm an amateur radio operators to those who have never really come across such a thing before, they invariably look a bit lost and then blurt out something meaningless about 'CB radio'.  They also have a pretty anoraky view of us all, a view that this club only very strongly reinforced.

I've come to thinking that committee-structured clubs, whatever the hobby, are an anachronism and belong to the distant past. Petty committee politics are always playing around in the background somewhere, and people today simply have no interest in it.  They can do their own thing, learning from the web, without those politics and patronising attitudes.  I dare say that is a good thing, actually.

 

Short Antenna for 40m: Reload!

Late last year, I threw up a shortened antenna for 40m using a coil in the lower 1/3 of a 5m-long elevated vertical. This allowed my 7m fishing pole, which is much more manageable in our regular, strong winds than a 10m version, to be used for all bands.

The idea is to make a multiband antenna that is easily carried down the beach and doesn't cost much.  I also would like to use it at home on lower bands, where it can tolerate very high winds.  Being able to get away from any home QTH is always a good idea to keep fresh, because you never know when someone will start spoiling your potentially huge investment with RFI.

The first coil worked pretty well, but I couldn't get the best match.  I think that was because I used short radials, rather than tuned, 1/4 wave units for a given band.  Even so, the match was reasonable, at about 1.7:1.

With better weather of late, I turned again to having a go at making a coil to allow a much better match on 40m, using tuned radials.

Even in summer, our winds can be strong!  Initial coil testing at 40m.

 
Initially, I had started making a copy of the PAC12-type antenna, made of alumimium rods.  I found this very slow going, not least because I had to cut my own threads and make connectors for the various components, made worse by Imperial measurements!

It also became clear, as I put the first bits together, that an aluminium rod antenna with a long telescopic whip on top was simply not going to survive on a North Wales beach, where we regularly suffer some of the strongest winds on the planet.

So, back to good old-fashioned, wind-resistant fishing poles!

I wound a coil of about 20 turns on a 43mm PVC pipe, with a split pipe of the same diameter slipped over the first.  This creates a slightly wider former, with a gap down the length, allowing a crocodile clip or similar to be easily connected at various coil positions.

The split second tube slipped over the first creates a gap for a matching clip. This is the second experimental coil.

The coil, being very light, simply attaches with a re-openable cable tie to the pole. It looks much less neat than a coil incorporated into the body of a PAC12-type antenna, but that's just unimportant!

My loosely wound coil was disappointing at first, as it showed a rather poor match.  I decided to push to turns much closer together, such that each was spaced by only about 4-5mm.  Immediately, this brought a perfect match with the whole length of the coil used.

The next step will be to make a set of tuned radials for more bands.  The photo above shows my new coil drying in the sun.  This has about 8m of wire - at least double the turns of the first, closely-spaced, so that I can hopefully reach at least 60m. Some hard-setting mastic was used to initially keep the coil spacing in place (few adhesives will stick for long to the PVC tube itself, especially if left outdoors).

I'll be running the antenna on 40m with the first coil from tonight onwards on WSPR, using just 200mW.  A few hours last night showed the system to be working very well.

UPDATE:

Here are the initial WSPR results at 200mW.  The following plot is on the first overnight run, where the Kp index was slightly high, at around 4.  The comparison station is my usual reference station, a full wave horizontal loop in England:

Doing will, compared with a full loop.

In particular, I was very pleased to be one of only two or three UK stations being heard in ZS that evening:

On the second evening, with quieter geomagnetic conditions, the results were even better, again showing the benefit of a clear environment and sloping ground to the sea:

 

Second 12h run.  Nothing wrong with this antenna!