Rough conditions return.

The geomagnetic field was very disturbed overnight, with Kp = 7 for a time.  Aurora was forecast to be visible as far south as central UK (none was noticed, thought the weather was slightly hazy due to high pressure):

Image: IRF, Kiruna.

Image: NOAA.

As is usually the case, disturbances of this magnitude generate very energetic electrons, preventing rather than assisting winter night-time propagation at 14MHz.  At 23:48UT, all propagation on that band ceased, the last station being TF3HZ (inside the auroral oval).

It's interesting to note the signal from LU7AA:

On this occasion, the peaks in signal correspond to the commencement of sharp southerly dips in the vertical magnetic component, and the early recovery phases from the same events. 

Simple pleasures.

Not bad for a £80 SDR receiver (SDRPlay RSP1a) - the only WSPR station hearing the 5W from VE7PGB at 14MHz on the dark side this evening (one hour slot back from 20:11UT):

Strange spots from 2E0XLG

Very unusual step changes in the 14MHZ WSPR signal (0.2W) from 2E0XLG, who is only 150km or so from me.

The geomagnetic field was dead, with only a very minor disturbance from about 02UT onwards.  The atmospheric pressure is very high at present (1035hPa), and one is tempted to wonder whether tropospheric conditions might play a part.  One might expect this to be unlikely, but there is in fact published, peer-reviewed research on this, the full text of which I am hunting down.

Plots of my WSPR reception (only) are now generally without complete labels, as I simply don't have the time to make everything perfect on a daily basis. 

Compare the above plot with that of the same station on the following day (25-26/02/2019, to a longer time scale):

Anomalous spots from the Canadian west.

An interesting few DX spots came in from the far west of Canada around midnight on 14MHz WSPR receive here.

The geomagnetic field was very quiet, never above Kp = 1, but undergoing a northwards Z deviation at very high latitudes, but was a southerly deviation at slightly lower latitudes:

Image: Tromso Geophysical Laboratory.

The timing is clearer in the Kiruna plot:

Auroral model at time of first spot from VE7PGB.  Image: NOAA/SWPC.

The spots, which at -25dB SNR/2500HZ or so are robust, are highlighted against the backdrop of otherwise very local 2E signals.  Once again, the anomalous spots seem to broadly coincide with a recovery to quieter conditions.  Note also the single spot of KA5UMD.

As is fairly usual, other than a couple of TF stations (interestingly, within the auroral oval), nobody else on the European dark side (or much of anywhere outside the US) heard VE7PGB, VA7PP or KA5UMD.

The geographic and geometric conditions at 23:56UT are depicted thus:

Image: DX Atlas, with permission.

Delta loop gives me early warning!

The HF bands have been quite lively today, so I tried a couple of CQs at 28MHz using my 20m vertical delta loop on its first harmonic.  This normally yields a low SWR of about 1.2:1.

But on sending the FT8, I could see the SWR was fluctuating, indicating an intermittent break in the wire.

At 14MHz, because the current reaches zero at the apex, where there is a lot of physical stress due to high winds, a break there has no effect on the normal, efficient operation of the antenna as the pair of closely-spaced verticals that it effectively is, as the model in MMANA-GAL shows:

At 28MHz, the current isn't zero, and is in fact fairly large at the apex, which is why the break, which is almost certainly there, is evident at this frequency but not 14MHz:

So, there's a little job for me over the weekend.  Luckily, it's a very easy and quick job.

The break was indeed at the apex. 

Job done in about 45 minutes.  Total wire length = 22.0m.  Length from feedpoint to apex = 5.43m (feed to apex measured before strain relief loops are formed, which results in the length becoming a little shorter later.  Similarly, total wire length is that from which the strain relief loops are later made, i.e. no need to add a bit extra for strain relief loops).  SWR at 14MHz and 28MHz is very good, and low across both bands:

Strain relief at apex now uses the antenna wire looped over a simple insulator, then taped with self-amalgamating tape, and a single cable tie to keep it together.  This affords slightly less stress on the wire, but the previous, cable-tie and loop only arrangement lasted in fierce winds for over 4 years anyway.

Overnight WSPR Report, 2019 February 21-22

Things hotted up a little bit overnight, with the geomagnetic field showing a significant, sudden southerly swing in the Z component, and the Kp reaching 6 for a while:

This led to a very nice recovery of the 14MHz, 0.2W WSPR signal from 4Z1DZ for a couple of hours as the field reached its later stages of recovering to quieter conditions.  Even more interesting is the increase in the signal before the onset of the disturbance:

4Z1DZ 14MHz WSPR received by MW1CFN 21-22/02/2019

In other news, a nice warm southerly breeze has developed over Wales, the source being in north Africa.  This morning's dust-laden air led to a beautiful orange, Saharan sunrise.  Yesterday saw Scotland's highest ever February temperature of 18.3 degrees Celsius!

A tale of two, 2 echoes.

Some moderate geomagnetic disturbances last night, with the Kp briefly climbing to 3 around midnight.

No DX spots at all on 14MHz WSPR overnight, but a nice long series of local 2E spots, which warrant some analysis.

First, the very well-sited 2E0XLG, about 480m up in the Yorkshire Dales, 159km from me:

Then, the not very well-sited, indoor dipole of 2E0WVY, 100km away in Liverpool (both graphs to same X and Y scales):

It's interesting to see that the variations in signal strength are clearly greater for the open, hilltop site of 2E0XLG than for the enclosed dipole of 2E0WVY.  But both systems respond to geomagnetic variations in more-or-less similar ways. 

For example, both stations show a reduction in signal strength around 01:00UT, when the Z field was undergoing a northwards variation, and the X field undergoing a much greater reduction in strength.  At around 03:00UT, both stations undergo an increase in signal strength as the field restores to quieter conditions.

It's useful to note that even stations as close as these two, and in very different siting conditions, can still yield useful information about the geomagnetic field conditions.