21 May 2020

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!

1 comment:

Anonymous said...

Hi Roger,
as you probably remember I built a copy of your earth mode Tx some time ago and got very limited range results. I turns out there was a reason for this....
My next door neighbour recently had a new garden fence fitted and the guys employed to fit it had extreme trouble digging down to fit the posts. Apparently, about 30cm down they met concrete and had to jack-hammer into it to fit the posts. It turns out my neighbours' and my house were built on concrete 'islands' as the foundations because the original land would have been to unstable. It seems these 'islands' extended way beyond the footprint of the house including the garden areas.
I now realise I had hammered my copper earth rods into these concrete 'islands' and not normal soil, apart from the shallow topsoil. No wonder earth mode never worked for me!!! I also don't have a long wire wire feeding the rods as you have done, so no NVS mode antenna for me either.
One longstanding problem explained at last...Now all I need to do is find out why I have S9 noise level across all HF bands for the last 35 years....

73 Ken
Stay safe and well.