VLF news 2021

Experiments continue at very low frequencies by radio amateurs. This is an area where all can take part on RX as the antennas can be very small indeed, yet highly effective. This is one of the frontiers in our hobby.

It is honest that to radiate a sub-10kHz signal does need a big antenna and dedication. Nonetheless, we need far more monitoring stations on RX only.

In the past I have tried to keep abreast of happenings at extreme VLF with my website on sub-9kHz operation. If I fail to update quickly, there are links to very up-to-date information. In 2021, I shall do my best.

See https://sites.google.com/site/sub9khz/news21 .

See also https://sites.google.com/site/sub9khz/home .

See also https://sites.google.com/site/g3xbmqrp3/vlf .

VLF earth-mode

It is many years now since my health allowed me to carry out VLF earth-mode experiments. Results obtained with 5W and simple kit amazed me. I got a range of 6km and far further would have been possible. I kept a blog of my results which can be accessed via my website and old website at https://sites.google.com/site/g3xbmqrp/Home/earthmode (do not follow the links on the left of this old website as these are very very old and may not work).

As I understand it, OFCOM is not interested in licencing earth-mode kit as long as no "harmful interference to wireless telegraphy" is caused. To be honest,  I think conduction modes are a total puzzle to them! Without (free) software ranges would be much shorter.

See https://sites.google.com/site/g3xbmqrp3/vlf/8-97khz-earth-mode-transmitter .

SAQ (17.2kHz CW) reminder

On October 24th there will be a transmission from the historic SAQ in Sweden. Quite a few test their VLF systems with this. I have a QSL card from them from a transmission several years ago. It is on my shack wall.

See https://alexander.n.se/category/news/?lang=en

VLF earth-mode

Some years ago G6ALB did some earth-mode tests with me. He was running 40W and was a very strong signal with me 3km away in the next village as the photo shows. He is the QRSS signal, not the wobbly line! This was at the old QTH. This was at 8.7kHz.

Amateur VLF

There is a myth that VLF antennas are big. For RX they can be very very small!! So, for RX only, amateur VLF is remarkably accessible.

For TX high power and big antennas certainly help.   DK7FC has had some excellent results with long distances using earth probe antennas. These don't require very huge loading coils.

VLF amateur work requires dedication, although VLF earth-mode can give good results with quite simple kit. This is certainly one of the frontiers ripe for experiments.

See https://sites.google.com/site/g3xbmqrp3/vlf

VLF tests in Devon

A couple of stations in South Devon, G3WCB and G4IUG are doing some tests with sub-10kHz transmissions with earth-electrodes. They can use high power and GPS lock. So far they have covered 1km with Hellschreiber. They can cover far further. It would not surprise me if they were spotted by Paul Nicholson in Yorkshire as long as they can send a long stable signal that can be integrated. This may need days of integration.

See https://sites.google.com/site/sub9khz/news20 for more information.

Amateur VLF experiments

One of the great things about our hobby is that it can be enjoyed in so many ways. Some get excited by amateur TV, some just enjoy a good chat, others like DXing, others EME and so on.

When I was fitter, I enjoyed experimenting with VLF. Several European amateurs were detected around 8kHz. My own thing was "earth-mode" VLF which involved injecting a signal at home (5W) then going out in the car to see where it could be detected. 6km was possible and far further was probably possible, but my stroke got in the way sadly.

To this day, I still host the Sub-9kHz Amateur Radio page and you may get some useful pointers from my old blogs. It would be great if someone carried this forwards as it is an area ripe for simple experiments.

See https://sites.google.com/site/g3xbmqrp3/vlf/8-97khz-earth-mode-transmitter

See https://sites.google.com/site/g3xbmqrp3/vlf

See https://sites.google.com/site/g3xbmqrp/Home/earthmode. This is on my old website which is not maintained, so do not follow the links on the left that may not work!

VLF earth-mode blog.

Years ago one of my favourite activities was experimenting with VLF earth-mode communications through the ground.

I would put a beacon on at home and go out to see where it could be copied.  Ranges surprised me and far further would be possible. Sadly, I can no longer do these experiments, but this is a rich seam ripe for others to carry on. Certainly higher power and bigger baselines would help. At some point signals that are radiated would be detectable at great range. Very stable (GPS locked?) signals would allow very long integration times.

My blog is still there on my original website. Hopefully, this will give you some ideas.  This old website is not maintained, so please do not follow the links on the left as they may not work!

See https://sites.google.com/site/g3xbmqrp/Home/earthmode

Sub 9kHz amateur radio

These days a dedicated bunch of amateurs continue to "push the envelope" by experimenting below 9kHz. At one time though getting outside the garden would be seen as amazing with the small antennas and low powers possible by amateurs. In actual fact amateurs have crossed the Atlantic! Although I don't claim to be always up to date, I try to be on my sub-9kHz website. If you are interested, take a look.

One myth is you need big antennas. On TX this helps with radiated signals, but on VLF RX they can be very small. An E-field probe just a few centimetres long can be very effective.

VLF upconverter

Some years ago I needed a VLF upconverter so I could listen for SAQ on 17.2kHz CW. The converter(s) here might be of use to help you copy some of the commercial VLF stations. It will not help copy most amateur VLF stations where frequency accuracy and long integration times are needed.

If my memory serves me right, this design of mine appeared in GQRP SPRAT, although I cannot remember which one it was.

See https://sites.google.com/site/g3xbmqrp3/vlf/vlfconv

Sub-9kHz transatlantic DX

VO1NA has been successfully decoded on EbNaut in Europe.

See https://groups.io/g/rsgb-lf-group/topic/vlf_vo1na_8270_0075_hz/61873847?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,61873847

VLF amateur radio experiments

8.97kHz earth-mode TX

The conventional wisdom is that VLF requires huge antennas and enormous powers. This not the case and radio amateurs have spanned thousands of kilometres with back garden antennas and modest powers. With utilities assisted earth mode (what I tried) just a few watts is enough to span very useful distances. For RX only, VLF antennas can be very small indeed.

In the past I have copied radiated signals from amateurs below 10kHz from several Western European countries.

Sadly my poor health has put a stop to my earth-mode experiments in recent years.

See https://sites.google.com/site/g3xbmqrp3/vlf/8-97khz-earth-mode-transmitter

VLF amateur radio

For several years I have tried to maintain a website about VLF amateur radio. Experiments are mainly done by a few keen amateurs. To receive VLF amateurs does not require a big antenna. To radiate a VLF signal to some distance does require a big antenna.

A casual listen at VLF will not result in success with amateur VLF signals. Most require highly stable signals (usually locked with GPS or a VLF MSK commercial signal) and integration over many hours or even days.

See https://sites.google.com/site/sub9khz/

LF and VLF ideas

In recent years there has been an increasing interest in amateur VLF work. You may find some ideas on my webpage.

Although big antennas and high power help on TX, this is not so on RX where some very compact antennas can be really effective. E-field probes are very small yet are very effective VLF RX antennas. They are every bit as effective as much larger antennas.

See https://sites.google.com/site/g3xbmqrp3/vlf

SAQ VLF (17.2kHz CW) transmission TODAY

A few times a year, the historic VLF alternator TX is fired up. Today is one of those rare times.

See  https://alexander.n.se/the-radio-station-saq-grimeton/saq-transmissions/?lang=en

Grimeton VLF CW transmission - June 30th

Southgate News reports on an upcoming 17.2kHz CW transmission from the Grimeton TX in Sweden using the callsign SAQ. On my wall I have a QSL card from them for a transmission many years ago. This very old VLF transmitter uses an alternator to generate the signal. It is now a world heritage site.

See http://southgatearc.org/news/2019/june/saq-grimeton-transmission.htm#.XQYyyPZFy00

Was this an April fools joke that ran and ran?

For some weeks now I have seen articles reporting a novel VLF antenna that is extremely tiny. This is meant to be a TX antenna! Now, this may be genuine, but it has the ring of an April fools joke with legs! If you know this is genuine, please let me know.

See https://www6.slac.stanford.edu/news/2019-04-12-slac-develops-novel-compact-antenna-communicating-where-radios-fail.aspx

Very tiny VLF TX antenna?

Just possibly this research could lead to compact (inches only length) VLF transmitting antennae. This link was sent to me by Jay W5OLF, who designed my 10m WSPR beacon, which is still working fine.

See https://phys.org/news/2019-04-slac-compact-antenna-radios.html

Successful amateur VLF TX tests from Poland

Transmissions from Poland at 8.27kHz VLF have been received in the UK. The antenna used was a long baseline earth-electrode "antenna".  From my own experiments with far shorter baselines, I know such structures work.

See https://klubnl.pl/wpr/en/index.php/2019/03/03/nadawcze-proby-z-dipolem-ziemnym-w-zakresie-vlf/

Earth-mode VLF

Yesterday, I mentioned amateur VLF experiments below 9kHz. A very accessible introduction is earth-mode communications, especially utilities assisted earth mode. Using the latter mode, 6km has been spanned,  with just 5W, although much further should be possible. With much higher power and larger baselines at the TX end, I expect the small radiated power will be detectable hundreds of km away, although this is not going to be earth-mode.

An example of a typical earth-mode VLF transmitter is shown at the link.