WSPRLite Test - Magloop on 40m

Having run very successful week-long transmissions on 20 and 30m using 200mW WSPR recently, I turned by attention earlier this week to the final test for now - on 40m.

The approach of a particularly severe storm - 'Doris,' meant the 40m test had to be curtailed after only two and a half days.

The results are extremely favourable in comparison with an OCFD atop a clear hill:

Magloop (blue) vs. OCFD (red)

The advantage of the magloop is that, for the most part, it keeps up with the OCFD most of the time, and is somewhat superior to it during the night time.

Now, a comparison with a doublet, which returns an even better result:

Magloop (blue) vs. Doublet (red)

And finally, the magloop loses out significantly to a 'skywire' type horizontal loop, which has much better night time performance:

Magloop (blue) vs. Skywire loop (red)

As always, take the results in context.  Overall, and considering the antenna is just 1.2m across and covers down to 5MHz, the achievement of the loop is really quite outstanding.  Certainly, those people who keep bleating on that a small loop is nothing more than a dummy load are once again definitively proven wrong, even on 40m, where a small loop of this size is starting to lose efficiency.

New Laptop, New RFI.

After six trusty years of heavy daily use, my Samsung netbook has finally given up the ghost.

Enter a brand-new HP14-AN001NA E2 laptop, a pretty good bargain offering from Tesco here in the UK, selling for just £239.

Having hooked everything from the station up to the HP, there was no immediately-evident RFI.  I was quite pleased.  Pleased, that is, until I switched to 24MHz, a band that remains surprisingly active, despite the lack of solar excitement and the belief amongst many ops that it is a dead band.

Whilst the RFI was narrow, rather than broad band, it was quite strong at 24.917 - slap-bang in the middle of the JT65A window. 

Rather despairing of the sheer number of RFI-generating consumer goods now overwhelming the hobby, I took to adding a wire of about 2m length to the chassis of the laptop, via the shell of the HDMI socket, using a small crocodile clip.

Voila!  The chassis is detuned such that the RFI vanishes at ham frequenices.  No further action necessary!

More WSPRlite Testing: Single vs. Triple Magnetic Loop

G3JKF runs probably the definitive magnetic loop on WSPR across many bands.  He and I have exchanged thoughts many times, and continue to do so.

I encouraged Ken to buy a WSPRlite last week, and we had a brief meeting on 30m where his triple loop array could run against my single loop.  Ken's construction is very careful and considered, as he has a long career in electronics enginnering.

This is how the loops, running 200mW, compared.  My single turn, 28mm copper pipe loop is in blue, Ken's triple, 15mm pipe loop in red:

In terms of the average distance achieved, the two loops were identical, coming in on that day at 6.6% of the maximum possible (antipodan) distance.  Ken's loop managed a greater distance periodically.

Overall, there isn't an awful lot to choose between the two loops, but it's clearly worth adding a bit more metal if you can manage it.

The question of whether a loop is any good and can keep up with full-sized antennas is one that is dominated by each antenna's environment.

For example, here's the week-long loop run against a doublet end fed wire run by the WSPRlite maker:

Clearly, the loop does better than this particular doublet by all measures during the whole run.  Notably, the loop keeps going through the night, whereas the doublet EF wire drops out for long periods.

Here's a comparison with an inverted-L, tuned at the base:

The loop is not quite as good as the inverted-L, but it does very well, nevertheless, especially when one considers the difference in physical size and the simplicity with which a loop can be installed.

And, finally, few people have anything bad to say about a loft dipole.  Yet, many criticise magnetic loops as just 'dummy loads'.  Here's why that view is utterly misguided:

Again, and whilst the loft dipole wasn't running some of the time, the magnetic loop does better at all points.

So the message is always the same: a well-made magnetic loop in a good, clear environment can do as well as or better than full-sized wire antennas in many cases.

Homebrew Magloop vs. Butternut Vertical, and Others.

Thanks to a rare spell of cold, fairly calm and, above all, dry winter weather this week, I've had a chance to stick my magloop out in the garden attached to my WSPRlite unit at 200mW out.

I'm amazed that the WSPRlite is able to handle the sub-zero temperatures, all without a hint of drift.  That said, someone from Norway is running his at -17 degrees Celsius, so it's clearly a very robust unit!

On initial assessment, it looked as though my magloop wasn't doing terribly well, because the reach of the signal was only really as far as the Canary Islands.  But I then started comparing my results against other stations, using the very useful DXplorer webware.  This showed that it wasn't the antenna, but poor propagation conditions that was the cause of the short reach.

This comparison revealed, again and again, a magloop that was doing almost as well as, and sometimes better than, full-sized antennas like the Butternut vertical operated by G0MJW, a plot for which is given below.  The only time it does poorly is during the later evening, apparently a result of having a low elevation pattern (not detecting high angle, short skip signals).

The only thing to do now is build-up the data and see how things pan out over time.

For sure, those who say that magloops are of no use are definitely wrong!  Also nice to remember that my magloop,even with new 28mm copper tube, cost only about £40, when the Butternut is several hundred pounds!

UPDATE.

Encouraged by the surprisingly good performance of my loop, I set things up for 30m the following day, where propagation was considerably better.

I compared my loop with known antennas - G3CWI running a doublet, and G7TSX running an inverted-L.

Again, the results were excellent.  Indeed, over the 1-day run, which I accept needs lengthening (the run is still ongoing), the magloop in this environment beats the socks off the doublet in its environment on both mean and maximum distances spotted.  For the inverted-L, my loop is essentially the same on the mean distance, and very slightly behind on maximum distance.  Remember my loop is just 1.5m off the ground, and only 1.2m per side!

My loop (blue) vs. a doublet (red)

My loop vs. an inverted-L.

I've no doubt that, if I were to run a doublet and/or inverted-L in the same location as my loop, it would be a little behind in comparison.  But there's the rub - from the right location, a magloop can indeed be as good as and even better than a full-sized wire antenna in a somewhat less ideal location.

So, the main message is: don't take what others say about any particular antenna as Gospel, because they know nothing about your environment, and are probably ignoring or underestimating the effect of theirs!

WSPRlite 200mW - The Results

This is more a diary entry for my records than anything of interest to readers, but it might be of use, nonetheless.

For just under a week, I've run WSPRlite at 200mW output into a vertical delta loop antenna, fed by 300 Ohm twin via a 6:1 balun.

The comparison station - G7CKX - has been chosen as one of the best-heard by others, and running the same power as me.  I've carefully gone through many stations and contacted operators about antenna details.  It's clear that the overall pattern shown by the comparison station is entirely representative of what all other stations running the same power with simple antennas showed.  In some cases, my antenna matched the distances achieved by others running up to 5W (a 14dB greater output.)

The first obvious difference is that, in this case and for all others consulted, there is a considerable difference, in my favour, in both average (+6.4% of possible) and maximum (+10.3% of maximum) distances reached.

Secondly, it's clear that my vertical loop acts in an extremely consistent way from day to day.  There's a sharp rise as the ionosphere is lit, a small step in the morning, and then a steep climb to a very steady peak distance for some hours prior to the band closing even more sharply in the mid-evening (February 2017).

The other antenna, which seems characteristic of a dipole, shows distinct peaks and troughs which are not present in my vertical antenna.  This probably reflects the directionality of a dipole, and may also highlight some elevation pattern changes, evident as the day progresses.

What is clear is that my delta loop performs very well indeed and, at last, I have some objective data with which to back this claim up.  The overwhelmingly important factors are a superb ground (an old copper mine) and an undeveloped, elevated position overlooking the sea. 

The real lesson for others reading this is: don't necessarily accept what others tell you about how and why antennas perform.  Exactly what you will get out of any given antenna depends very critically on the environment - something that the majority of urban-prone operators simply fail - and often refuse - to accept.

For interest, this is the plot of people hearing both stations mentioned above:

MW1CFN (blue), G7CKX (red), both (green)  Apologies to the colour 'blind'!

VHF Contest Rules - A Petition.

Please sign this petition, set up by G8LZE (David Dix) in support of a review of VHF contesting rules set by the RSGB, as soon as you can.

RSGB VHF Contest Rules, Contested.

This is a response from David Dix, who is leading a campaign to challenge recent RSGB changes to VHF contest rules:

Picking up trouble. Image: KB5WIA.

"Until this year the scoring system for RSGB UKAC contests was based on a “multiplier” system where each new main QRA square, ie. IO82, gave a multiplier of 2 to the points per kilometre, PPK, score. So a station making 20 complete QSO with a sum total distance of 3600km with stations in 5 different QRA squares gave a total contest score of 3600 x 5 x 2 = 36000 points.

Some stations on the periphery of the UK, felt they were disadvantaged under this system, so the RSGB VHF contest committee tried to originate a scoring system that would "level the playing field" this despite the 2015 RSGB Presidential Review of contesting final document concluding:-

"It is difficult to achieve fairness across the UK and there is a danger of adding to the complexity of the scoring system. A practical approach is to do the right thing for the bulk of the population at the same time as taking all reasonable steps to eliminate bias."

The proposed revised scoring system, B2, is based on the same PPK but different QRA squares attract a one off bonus for the first station worked in that square. Colour coding of QRA squares gave red squares a bonus of 2000 points, green squares 1000 points and blue squares 500. Generally speaking red squares are Scottish, green squares cover northern England while blue squares cover southern England and east anglia.

VHFCC did much computer modelling and declared the new B2 system fairer however many regular contesters did not agree and warned that the system would skew results as the data used was averaged and hid a number of anomalies.

Despite these representations and more people in a consultation not voting for the introduction of B2 it was introduced in January 2017 and already the skew of results is clear. Just as an example:- in the 23cms contest on 17^th January a Scottish station made just 5 QSO's with a total distance of 353 km but accrued 6000 bonus points giving a total of 6353 points. He beat the next station in the results table who was in England made 26 QSO's with a total distance of 2444 km but only 3000 bonus points giving a total of 5444 points.

This clearly demonstrates that rather than “levelling the playing field” the reverse has, in fact, occurred.

Much analysis is available at http://vhfgroup.co.uk/ which compares the different scoring systems derived from actual contest open logs.

What became clear when looking into the process is that no VHFCC meeting minutes had been published in breach of the RSGB's own bye-laws (now published) retrospectively but their accuracy is questionable as the March 2016 minutes carry the footer from the November 2016 minutes.

The whole operation of VHFCC and it's “consultation” was far from transparent or responsive, as required by the RSGB's own code of conduct, and some key questions still remain unanswered despite representations to the main RSGB Board whose governance during this period is also open to question.

This lack of transparency and active communication with members has resulted in bad feeling that a set of rules has been foisted on the VHF/UHF contesting community, despite a majority having voted against them, and has bred an atmosphere of distrust and the circulation of many conspiracy theories.

A possible light at the end of the tunnel is that the current RSGB President, Nick Henwood G3RWF, has announced a review of the 2015 review which may provide an opportunity to rectify some of the irregularities.

The aim of the petition https://www.change.org/p/david-g8lze-help-improve-vhf-uhf-contesting-in-the-uk is to try and get 300 signatures by 24^th February which may well open the door for a discussion at the forthcoming AGM in April."