@mw1cfn_radio

 

Yes folks, it's high time I was on Twitter!  

So, for short updates on what I'm up to from day to day, do please follow:

@mw1cfn_radio

See you there! (I will continue on here with posts that merit a longer treatment)

Not quite what was expected

A forecast for a fairly major, G3 disturbance became reality last night, although the peak was fairly short lived:

It's always interesting to note what happens on the north-south circuit during these events.  DP0GVN in Antarctica vanished at 10MHz with the onset of the disturbance, but at peak field deviation, yielded a single spot, only to vanish again until the advancing morning propagation.

Reception of DP0GVN (5W) at 10MHz at MW1CFN.

The effect of the disturbance is also very clear when we plot all received distances of spots against time - a big gap develops for around three hours from around the midnight point.  Indeed, it was only spots from TA4/G8SCU that kept things going at all in this gap, with a couple from SV1DAR, too, both running 5W:

40m Beach test.

A nice starry evening after loads of rain tonight.  Ideal to try 40m at the beach with the new Ampro!

Just me and the lights of the ships going to Liverpool.

 

I couldn't lower the SWR below about 1.5:1 just by adjusting the stainless steel whip.  Whilst I could use the TS480's ATU, I don't really like to use that unless it's for a much smaller correction to the matching.

Night-time shunt coil test, which worked nicely to bring the matching under control.

 

By now, I have a real mobile shack - everything, including a ready-made shunt coil and connectors - is sitting somewhere on the back seat, in the glove compartments, or in the boot!  I added this at the base and: voila!  A 1:1 match out of the box, without any adjusting of the coil!  The whole thing is quite narrow banded, but that's fine with almost fixed-frequency digimodes.

It's really nice working /P at night.  Nobody around, owls and seabirds making their respective noises, stars in the sky, and that warm glow from the radio display that pulls the mind into all those far-away places from which the signals are arriving - just like the good old days of SW valve sets!

Back to the modern world, the FT8 signals at 15W looked pretty good:

I then went to WSPR at 1W.  This worked exceptionally well from the beach.  Here's VK3KHZ's receptions either side of my being heard, where, as you can see, no other UK station was making it across to him at all.  Taking a detection limit of -34dB for WSPR, this result suggests I'm getting at least a 10-14dB enhancement over any other UK station:

Next, VK5ATN/B, where I was again the only UK station getting across.  This suggests at least an 8dB gain over other UK stations:

And finally,VK2OB, where only G4NEY and I were getting across.  I think he uses a dipole.  I'm getting only 3dB over him, but his set up must be very good to be the only other G station making it, and we must be at least 11dB better than other stations in the country for them not to be heard:

Any ideas?

Whilst playing around on 7MHz last night, I could hear this fairly weak, descending tone CW, which is evident on the waterfall, initially starting off at 800Hz, but going down to 450Hz.  Is it old equipment (seems extreme), a propagation effect, or what? 

Of course, it vanished before I could get a video of it!

 

New stick (yes, another one!)

An exceptionally rainy 72 hours brought quite serious flooding to North Wales yesterday.  Although I've seen significantly worse floods, I also saw severe floods in places I've never seen flood before.  Some of this is due to 'improved' agricultural land drainage, which keeps fields drier, but rivers much fuller.  

Mobile post office van didn't make it!  Never seen flooding of this scale here before.

During the rain, the postman delivered a 40m Ampro antenna here. The idea with this is so that I can spend some of the long winter nights at the coast playing radio.

Incidentally, beware imitations of the Ampro sticks.  I recently bought a 15m stick that turned out not to be an Ampro, which works perfectly well, but has fragile shrinking plastic covering, which has cracked at several places where the wire runs underneath; it looks like a pattern that would form if the plastic melted under too much power, but it's just broken. 

RX reports for my ~15W from the 40m stick.  Terminator is about 30 minutes after these reports.

Inevitably, a 40m band antenna that's roughly 2 and a half metres long is a bit of a compromise.  That said, even in wet weather, which always adversely affects magmounted antennas a little, I managed to quickly match it down to around 1.5:1 at the side of the road as I waited for my son to finish work.  I expect in dry weather and over a beach, it will come down to around 1.2:1.

WSPR RX (red) and TX (1W, green) over 64 minutes, including whilst moving /P

 

Not many G stations were getting across to KD2OM at the time on WSPR, so I was happy to be one of them.  Being in Scotland seems to give an advantage on 7MHz!

On the usual 15W or so, I managed plenty of QSOs on FT8, and did a small amount of WSPR.  I'm perfectly happy with what the antenna is doing, and I look forward to starry (OK, mostly cloudy, wet and windy) skies with my radio this winter!

The evening ended with encountering a car crash.  The police officer who told us the road was closed ahead must have wondered what the big antenna on the car was for, but didn't say anything!

10m going great guns!

Past 24 hours,almost all RX on 28MHz.  It's a great time to get into or come back to amateur radio - no complex equipment needed!

14MHz, 50cm tall antenna takes shape.

Following on from a very successful trial of a 50cm tall, 28MHz antenna recently, I moved on to 14MHz, where it may be easier to get a 1W signal further, and more consistently, than on the upper band.

The coil for this, based on a 50mm diameter PVC tube, is about 24cm long, with somewhere around 43 turns needed for resonance.  I guessed it might take slightly fewer turns, but I ended-up slightly short in the end, hitting 14.8MHz.

The early rule suggested by PE4BAS for the '50cm antenna challenge' is that the radiator, including the physical length of the coil (not the wire length in the coil), must be 50cm or less.  Radials were envisaged as being permissible (some might say 'essential'!)

Three questions then arose: 

(1) With such a short antenna, are the radials likely to become part of, or even the main, radiating component?

(3)  Should radials be allowed to be full length, or also limited to a maximum of 50cm?

(2) Should radials be disallowed?

I haven't had time to look at my radials and any radiation that may occur from them yet.  I suspect I may well find radiation when I come to examine them properly.

So, for my 14MHz build, I disposed of the radials, and connected the coax sheath to a copper tube ground connection instead.  Without any attempt to perfect things at all, I was already at a SWR of about 2:1 at 14.8MHz.  

I expect that, with a further few coils added to bring the resonance down to the bottom of the 14MHz band, and perhaps a shunt coil across the feedpoint (if needed), then it will be down to a good match and ready for tests.

Of course, soil conditions will mean adjustment of the antenna will very likely be needed from site to site, and even day to day, according to weather.  Usually, this is adequately achieved by a small adjustment of feedpoint height above ground.

More to come, as soon as I have good weather to do the tests, and I've seen the film 'Dune'!

Small antenna - progress, of sorts (UPDATED)

Had a quick attempt to make an antenna for 28MHz within a length restriction of 50cm this afternoon.

I used online calculators to guesstimate the correct loading for a top coil, which came out as 23 turns - I actually needed only 20 - on a 50mm diameter PVC tube, placed 37cm up from the feedpoint.  I used a random wire radial, which turned out to be roughly 2m long.

 

Ugly as hell.  38cm of wire and a 20-turn coil on top, plus radial.

Placed at about 30cm from the ground, the initial match was quite encouraging - 1.7:1 - and the coil was resonating things nicely, if extremely narrowly, at the bottom end of 28MHz - perfect for FT8, but pretty useless across the rest of the band.  That's the price to pay for a very small antenna, of course!  I later managed to get it down to 1.5:1, by sloping the radial up from the feedpoint. 

On adding a second radial, and adjusting the position of the base relative to ground slightly (the height on any given day will change with ground moisture, rain, etc for such a narrow banded antenna), I managed to significantly improve the matching.  This is where I'm at now, ready for some testing tomorrow (note the vertical scale is now zoomed in):

[UPDATE]

A mostly receive-only test for ~3 hours this morning, from a truly rubbish domestic testing environment, shows good promise with FT8, remembering also that this is less than 1/20th wave tall!  Strongest TX from here was -9dB into UR3QL, and farthest so far R3KDV at 2925km, -14dB.  1W at the beach will be boosted to about 10-15W, so this 15W garden test might be very approximately what I might see there (although I expect the clear environment to mean it will be much better in practice).  Indonesia (YE9CDL) came in at a very healthy -8dB.

50cm Antenna for 28MHz.

My blogging colleague, PE4BAS, recently posted a very interesting piece about his early ideas for a QRP contest.

The sting in the tail is the maximum permitted radiator length: 50cm!  The band can be any (not just 28MHz, as I wrongly indicated earlier).

I sent a comment that this was something I would definitely take part in.  As Bas says, the ideas are at an early stage, and there is plenty about the rules to iron-out first.  I completely get that.

I wondered about a magnetic loop, first of all.  These are very efficient, typically in excess of 95% at higher frequencies with 'microbore' copper tubing. 50cm is probably possible as a radiator length, but it's so small that it won't be efficient at all, in all likelihood.

My small 4-loop array which I tested against (and beat) a large delta loop at 28MHz earlier this summer.  It's 45cm across, but each radiator is (pi x d) longer than that.

 

I then wondered if Bas would allow a 50cm diameter loop?  If not, and if I then limited the radiator length to 50cm, how about when I make a parallel array of them?  Is it then a size of no more than 50cm in any dimension?  

I completley accept this goes a little against the spirit of what Bas is trying to do; it's not in any way a criticism, just an interesting reflection of what might be possible - and what might not.  But if the idea gets a lot of support - and I'm sure it will - then people will look for ways to get a good signal whilst exploiting any weaknesses or oversights in the rules.

But then, if we are going to limit ourselves to what Bas originally seems to have had in mind - a 50cm vertical antenna - then we are going to need to use loading. 

The MRW-27L (27-28MHz) 'Super Gainer' (probably not) vertical.  But it seems to include a lot more wire than that, in the form of closely-wound, very fine wire coils, making it longer than 50cm in reality.

 

Adding such a loading coil inevitably means adding quite a decent length of wire, but compressed into a small length.  Do we add the total length of the wire to the calculation, or just the physical space it occupies?  With such a small antenna limit, I think we have to accept that the overall physical size of the radiator has to be kept to within 50cm, where the coil's physical length, rather than the coil wire's length, is the measured value.

As always, coming up with new rules means there are many ways, certainly when it comes to antenna designs, in which things can be overlooked!  I've got a working and fairly efficient model made up at 28MHz, but the lower bands need some thought, too.

Good higher HF day (photo journal)

After some extremely wet weather over the past couple of days - minor flooding of fields is already happening locally - the sun came out today.  But not before some very heavy showers passed through mid-morning, and some snow had been deposited above 900m on the mountains of Eryri (Snowdonia).

View from the shack window (car!) early on.

So, here comes the radio bit first - just the higher bands of 12 and 10m from the beach today.  Best actual QSOs on 10m were 3B9FR at 10,374km from 20W into the stick antenna, followed by E20EHQ at 9,733km.  

On 12m, I was regularly hitting RA/UA9 regions in Russia in terms of QSOs, but also being heard in JA and VK - with a very good -9dB into VK4ABW (which is a monitoring station) at 14,004km - China and India.

12m (red) and 10m (pink) activity this mid-late morning.

The beach site is also a great place to have a good walk, relax, and look at nature.  The tides, whilst naturally defining the passage of time, are in some sense timeless; the future in just over 6 hours' time is certain - the low tide will return to high.  Birds line up, right on time for high water, knowing very well that their food will be uncovered in just a few minutes.  

A flock of Oystercatchers (Haematopus longirostris) heads for early exposed sand - and food!

 

The beach is so shallow here - it slopes maybe about 2m over 2km - that the water goes out quickly.  One can slowly walk out with the tide, only sometimes stopping for a minute or two for occasional hollows to become shallower.  It's possible to walk out and be completely surrounded by water, which is a unique and rather odd experience!

A ~300 degree panorama.  I'm about 1km out, standing in and surrounded by the sea!

 

The area has very rich shellfish beds, but has been closed to cockle pickers for some time, to allow populations to recover.  Unfortunately, gangs often descend from north west England here, stripping the area bare in what can be a very lucrative, and sometimes criminal-linked business.

An empty Razor Shell (Ensis ensis)

Remains of an old boat near the mean low water line.

6 metres, 6 weeks.

Well, after a lot of thought, I've opted for a 3-element Yagi for portable 6m operations.  

Although there are a number of good antenna makers out there, I have a definite preference for Innovantennas, who made my 12m LFA.  That antenna, as I've highlighted many times, is extremely well-built and took one hurricane-force storm after another, for many years.  When I came to move recently, the whole thing dismantled smoothly in minutes.  It will see service again, one day.

Justin, G0KSC, was characteristically helpful in coming up with a modification of a standard 3-ele OWL Yagi, which will allow for easy compactification for car transport.  Due to high demand and, no doubt, difficulties we are all experiencing due to Brexit, this will take 6 weeks to be ready.  

The 4m version of the 3-ele OWL Yagi.  Image: Innovantennas.

Although it was tempting to go for a higher gain model, such an antenna would quickly become difficult to manage when portable.  Because I want to operate the antenna in vertical polarisation, to maximise the potential of the seaside, the rear-mounted 3-ele works out as a very good compromise.

Pattern in vertical polarisation for generic 3-ele Yagi.

 

Deployed at the beach, MMANA-GAL predicts just over 13dBi total gain at the horizon.   This may well prove interesting for summertime DX propagation to Japan, for example.  I typically use 15W when portable, sometimes pushing it to 25W when needed.  So I should see something like 546W effective output at that upper end, and 328W at the lower input end.

OZ7IGY, and other 28MHz fun

Good tide for some 10m and then 12m work this morning.

Conditions not wonderful for DX, but plenty of short-skip Es around:

10m (pink) and 10m (red) activity. 

I also heard this beacon quite nicely, which I think is OZ7IGY:

Higher HF is GO!

Pretty good conditions all the way up to 6m today, with the weekend activity only making matters even better!

When the upper HF bands are open, they are just that.  It doesn't matter so much what antenna or power you are using - you are going to have a good time, regardless.

For example, here's a portable GI working VO1FOG on 12m:

 

To highlight this fact, here's my plot of activity from the beach on 12 (red) and 10m (pink) with stick antennas.  The simplicty of the antenna type is very much more than compensated by the seaside environment:

Now compare this with my 10m-only operation (over a longer period during the day), mostly RX, with my decidely poor home location's antenna, a shallow, sloping multiband delta loop.

So, that saying 'when upper HF is open, a wet string will get you through' is, in fact, rather true - and never more so than now, when we have these sensitive digital modes at hand.

Over on 10m WSPR from the beach, I was pleased to get 1W across with a decent signal to Reunion - a distance of 10,000km (the first spot had an incorrect locator for me for some reason).

Goings on at the beach.

Very nice weather today, so an early morning trip to the beach again, to see what I could find.

Sunrise!

 

Unfortunately, thanks to something that sounds like a OHR somwhere, there was little point in trying any WSPR:

Over on SSB, there wasn't an awful lot happening there, although a couple of VK stations were in QSO with G stations to my east on the long path.  I didn't bother calling them, as they rarely want to be interrupted.  You can hear a two-ship formation of RAF Texans joining the circuit at RAF Valley in the background - a lovely sound!

There was also a JA on long path, with plenty of phase-induced QSB at times, though it may not be evident in this short video:

Low angles

I often write about the benefits of low angles on this blog in relation to getting signals to great distances, delaying the first skip off the ionosphere for as far as possible.

In the other of my lifelong interests, astronomy, one often uses hand dimensions as convenient, if somewhat approximate indicators of angular size.

So, in a quieter moment yesterday, I held out my little finger at arm's length, zoomed the phone camera until a ship on the horizon's image matched its size as seen by the eye, and took a photo. Obviously, the image quality is not spectacular, but it's good enough.

 

This provides a fairly good, visual indication of what one degree looks like on the sky.  The lines I've drawn are: yellow - 1 degree span; orange = 0.5 degrees, blue = 0.25 degrees, red = 0.125 degrees.  The apparent size of the Moon and Sun are much the same - about half a degree - and is represented as a circle to the right of the image.

I think this helps get a mental picture of how antennas over near-perfect ground like the sea can really get signals out at extremely low angles.  Even at 1/8 of a degree, there's still clear access to lower elevations, where the direct and reflected radiation combine with minimal phase difference.

50MHz, twin loop antenna

My curiosity was sparked on discovering the potential of simple wire antennas modelled in MMANA-GAL when using perfect ground settings recently.  Whilst seawater is not perfect ground, it is usually described as 'near-perfect' in radio texts.

I then had a look at other models, notably a centre-fed, two-loop array in vertical polarisation mode.

MMANA-GAL model of a centre-fed, two-loop array, with currents (red= vertical)

 

This model displays very interesting and useful characteristics, inasmuch as it shows multiple, strong lobes from the horizon to quite high angles.  Gain values range from 11.1dBi at the horizon, to ~ 8dBi at 40 degrees.  

Note that, when used at the coast, the rear lobe of the dipole-like pattern will diminish in strength due to the land in the opposite direction to the sea.  However, if working within large sandy or muddy flats, this is not so much the case, and the indicated pattern will tend to be what is realised.  There is no way to model this in any software I know of.

 

The higher lobes mean this antenna is less ideal for DX working, as nearby signals on shorter paths may swamp weaker, more distant signals.  It will certainly be a very capable general 6m antenna, with the added bonus of excellent DX capability when propagation favours it.

In practice, I typically put out 25W mean output on SSB, which is as much as is sensible when using a direct-to-car-battery supply, fed with fairly substantial wires.  At 11.12dBi, therefore, this 25W will get boosted to 323W by the antenna/environment system.  

The model in MMANA-GAL is for 435MHz.  It uses a VF of 0.88 for the wire, which is as we might expect and, so the 6m version results in 5.97m x 0.88 = 5.25m wire length per loop, or 1.31m per side.  This means a top and bottom support of timber, fibreglass or conducting pipe of 2.5m or 3m standard length should be adequate to build the antenna, with very slightly longer wire connecting those two elements if the 2.5m lengths are used at the top and bottom.

It looks like I have plenty of antenna building to come over the next weeks!

 

The morning after the night before.

It was a pretty rough night for the geomagentic field, thanks to the arrival of a CME from 9th October.  

Although I left 10m WSPR running overnight, no spots came in, nor did any of mine get out under the wild conditions.  That may change later in the day, as echoes from the mesosphere today may well indicate some Es could come to pass

 

It didn't look very good for HF operations this morning and, indeed, it wasn't!  The bands were open to 15m here, but it was largely one-way propagation, with those further south in Europe enjoying easier conditions.

So, I went for a long walk down to the water, as the tide reached its lowest point.  I left the rig running WSPR on 14MHz.

I was very happy to be the only UK station, and one of only 3 across Europe, reaching ZL2BCI, and with good signal levels, considering the simplicity of the set-up (stick antenna on the car at the beach):

Gem, or Junk?

I've been thinking a lot recently about how best to continue 6m operations.  With plenty of solar activity going on now, and the potential for 6m aurora, this isn't a decision I can put off much longer!

If I want a beam, I will almost certainly have to build one, because the present requirement is for a portable antenna that will dismantle and fit in a car without lots of swearing!

I was then idly looking at MMANA-GAL's models, and came across the 'Sky Door' antenna.  When I turned it on its side, to vertical polarisation, and placed the antenna on a virtual beach in the model, the output was, well, almost unbelievable!  

Pattern of vertically polarised radiation over perfect ground.

The antenna model, with horizontal (blue) and vertical (red) currents shown.

What do you think?  It doesn't look very probable that such a simple loop with a capacitor to match it up could really produce 11dBi gain, even at the coast.  If it's correct, then this is a far preferable option in every respect to a Yagi or other beam. 

But I've never had much cause to doubt the output of this software, so I've already got some 6mm aluminium tube on the way.  Whilst this is possibly not necessary, where it could be an all-wire antenna, both the model and the build on the web site does use tube, so I decided to try that first.

The best reference I could find to a real build of this antenna is found here, in German.  An appeal for any real-world experience on the UK 6 metre Group Facebook page produced no comments.  Even if someone had built it, it's very unlikely they would have taken it to the beach!

G3 disturbance

A large, sharp fluctuation in the geomagnetic field occurred late last evening, as a CME from October 9th arrived at Earth.  Forecasted to reach G2, preliminary results show a somewhat stronger, G3 event actually took place:

The commencement of the main disturbance, at around 21UT, led to a sudden collapse in my 1W, 10MHz signal to TF4X.  There were two, very weak spots of my signal there at around 22:30UT, when the field was rebounding to calmer conditions for a while:

TF4X receiving my 1W, 10MHz signal overnight.

 

TF4X didn't hear my signal again until a couple of closely-spaced spots at around 02:30UT, which appears to be related to the onset of the further field disturbance, which was by then felt more strongly to the west.

Vertical field component disturbances, East-to-West transect.

To confirm the result, my reception of 1W from TF3HZ, also on 10MHz, showed the same effect, and with the same timing, in the reverse direction:

My reception of TF3HZ, 1W, 10MHz.