12 years ago

Earth-mode experiments in 2011

 
This was my earth-mode signal 4.5km away from home in 2011 at 1.095 kHz using Spectran software on the PC. Strictly speaking, I suppose this is ULF!

It is a long time since I have done any earth-mode experiments, but my health has got in the way. It would be good to do some more experiments.

Sunspots - Wednesday April 12th 2023

Solar flux is 143 and the SSN 103. A=6 and K=1.

70cm activity contest

After copying no stations at all (!) I gave up. I expect the next 70cm FT8 activity contest will be much better!

80m FT8 (Tuesday)

As 6m was so poor, I QSYed to 80m FT8 using the earth-electrode "antenna" in the ground. Although I am receiving spots of my signal from right across Europe, it says I am receiving none. This is rubbish as I can see loads of stations locally. Either there is a delay with uploads from me or, more probably, my spots are not getting to PSKreporter. Shortly I shall do reset to see if this cures it.

UPDATE 1922z:  The reset did the trick with lots of spots on RX. On TX 36 unique station spots of me so far.

UPDATE 2119z:  112 stations have spotted my 10W 80m FT8 TX this evening. Now QRT on all bands.

6m FT8 (Tuesday)

In a word, hopeless. I have been on 6m FT8 for about a hour and have been spotted very strongly by just one station not too far away (50km). On RX absolutely nobody copied.

UPDATE 1708z: Still useless!  Just 2 stations have spotted me and I have spotted nobody! Soon be time to try another band. I might give 80m FT8 a go with the earth-electrode "antenna" in the ground - probably after tea.

Windmill next door - NOT amateur radio

This stunning photo of the windmill next door was taken by a neighbour K. Tingey. 

E-field probes (EFPs)

These are tiny receive only antennas that can work extremely effectively at VLF, LF and MF where external noise is usually the dominant factor. I guess as local external noise is increasingly the dominating factor, these will be as effective as a "big" antenna at even higher frequencies. At LF they can be only a few centimetres long, but be as effective as antennas hundreds of metre long. 

EFP on a mag mount
for 2200m RX

As the signal decreases, so does the external noise! Overall, nothing is lost. There is no advantage by using a large antenna at low frequencies for receive only. For TX efficiency, a large antenna and good earth help! A popular EFP design is that PA0RDT (Google it). I have made versions for LF and VLF with a tuned peak as shown in the circuit.

See https://sites.google.com/view/g3xbm4/home/antennas/137khz-efp-rx-antenna .

Tuesday plans

 Probably 6m FT8 later. Shopping first! 

Double rainbow - NOT amateur radio

April in the UK is a strange month. Some days can be warm and sunny, whereas others can be cold. Yesterday was a mix of sunshine and showers. The photo of the double rainbow was taken in haste from the lounge window. A few minutes later it had gone.

Sunspots - Tuesday April 11th 2023

Solar flux is 140 and the SSN 92. A=14 and K=0.

630m WSPR RX

At about 1940z, I switched to 630m WSPR RX with the earth-electrode "antenna" in the ground. So far, no spots.

UPDATE 2126z:  Several WSPR spots of DC0DX (467km) at up to -9dB S/N.

Earth-mode paper

 Someone asked for access to this file. It is now open so if you have this link you should be able to read it. It was sent to me some years ago.

See https://drive.google.com/file/d/16vtYNznORclXJTfpaT-RC7Z3IV8RKqyi/view?usp=sharing .

6m FT8 (Monday)

For about an hour, I have been on 6m FT8. So far, 13 stations have spotted me and 1 have had 1 QSO. I noticed the BNC plug was intermittent. Mending it took about an hour. In years gone by this would have taken me 5 minutes.

80m FT8 (Monday)

 At 1255z, I moved from 160m FT8 (no spots) to 80m FT8 using the earth-electrode "antenna" in the ground. The FT8 frequency on 80m seems to be 3.573 MHz.

160m FT8 (Monday)

 As my earth-electrode "antenna" is now matched, I am currently using it on 160m FT8 with 10W from the FT-710. No spots, although I am not surprised in daylight. I must double check on the 160m FT8 frequency in Europe. I have never tried FT8 on topband. I have used WSPR in the past. Currently I am on 1840 kHz FT8, which seems right.

UPDATE 1120z: This looks a useful resource for digital modes in Europe. See https://www.pa8s.nl/knowledge-base/frequencies-for-digital-modes/ 

Spots of me at 1814z

UPDATE 1814z:  Back on 160m FT8 with the earth electrode "antenna" in the ground. Running about 10W from the FT-710. 7 spots of me with the furthermost SM3PXO (1485km). Still daylight here for another hour. Oh yes, it works!!

UPDATE 1856z: 15 stations in 7 countries have so far spotted my 10W FT8 on 160m this evening in the daylight. And the antenna is invisible to my XYL!

UPDATE 2005z: My first FT8 QSO on topband with GM8IEM (753km). Although I was in beacon mode and not answering calls earlier, I see I was called by several stations including one in Denmark. 21 stations have spotted me tonight Now QRT on 160m FT8.

Museum open again - NOT amateur radio

Yesterday, after what has seemed a long winter, our local museum and windmill next door reopened. The weather was sunny and pleasant. Parking near our house is not usually an issue. It was yesterday!!

Monday plans

My main aim today is to match my earth-electrode "antenna" on MF. I I can do this, I can try it on FT8 or WSPR TX on 160m or 80m.

Later, I may try 10m QRP FT8 again with the QDX, although it does not teach me much - I know less than 5W of FT8 can get spotted across the planet. All these stations could be worked, but I do not have the energy to chase these!

UPDATE 1021z: After adding more turns to the primary of my 3C90 transformer I can get a perfect match on 160m and 80m with my earth electrode "antenna" with the auto-ATU in the FT-710. I shall try 160m WSPR or FT8 tonight!

2m activty contest (UKAC) last week

 Last Tuesday was the activity contest organised by the RSGB. My incredible score (I am joking!!) has just been submitted as I almost forgot. Tomorrow evening is the 70cm activity contest.

The impression I am getting is interest in this contest is waning with the FT8 contest on the following evening doing better. This is pity as it is a very "un"contest contest with people happy to see the activity levels up. I have been taking part for several years.

The stations contacted are shown on the map.

Earth-electrode "antenna"

My earth-electrode "antenna" has been reinstalled. 

Much to my surprise I am unable to tune it using the internal auto-ATU suggesting the impedance is greater than 150 ohms. 

I shall have to try a new matching transformer to bring it in range of my auto-ATU. This make take a few goes. I want a good match at MF.

Sunspots - Monday April 10th th 2023

Solar flux is 140 and the SSN 52. A=6 and K=3.