Tesla Coil Transmitter for the 40m Amateur Band

[@luisharaldo]

Great experiments.

[@andrewandrosow4797]

I had done several experiments. I used a coil with 2meter wire , connected to 50Ohm transmitter with 1W power.I installed this wire with a coil on a balcony outside. I am living on the 4 floor in a flat in a big city. I tested it on 7.2MHz, 2.457MHz, 27MHz. The distance was not more that 1Km. I tested it with online SDR receivers, but I had not had any success.As a ground plane I used a metal visor outside and a big piece of foil. I isolated a transmitter with ferrite toroid with supply cable (like a EMI filter in SMPS).But in my flat I measured RF voltage in power sockets (AC 220V) . There was 0.5V... So, all the metallic construction in a building are receiving RF signal.

[@DavidSkelhon]

Thanks for the comment. If you are in a city, surrounded by high levels of RFI, I am not surprised that you couldn’t hear the signal above the noise 1 km away. In my latest video, I am operating outside the city, away from conducting structures that potentially absorb the signal. One Watt is a very small amount of power when using an inefficient antenna but even so, under the right propagation conditions, a distant receiver in a quiet location may detect it. Unfortunately, in your high noise location it would be difficult to hear a response unless the other station was using an efficient setup and more power.

[@MasterIvo]

Still EM waves, but Tesla was very clear he used changing electrostatic potentials. I wonder if it is the same with the LMD resonant mode. I really advice everyone to read the 1891 lecture of Tesla (again) where he decribes the powerfull electrostatic effects which he later called Radiant energy. it behaves differently then the EM resonant mode (TEM)😊

[@DavidSkelhon]

Mainly TEM waves for sure, but there maybe a small LMD component too. Confirming it might be a subject for a for a future video.

[@MasterIvo]

@@DavidSkelhon I agree, both TEM- AND LMD resonant modes can be present.

[@till7253]

interesting video

[@SuperheroArmorychannel]

Amazing results for such a low watt low tech solution. Couldn’t the same concept be used with a large tesla coil?

[@DavidSkelhon]

I’m sure it could. The question is, how efficient is it compared, say, to a conventional dipole antenna? I suspect it will fall short but under some circumstances I could live with reduced efficiency if it is easier to deploy compared with 20m of wire strung between masts and trees. I will test it in the field and report back in the next video.

[@DavidSkelhon]

Absolutely, though I suspect this coil could handle several hundred Watts anyway.

[@DavidSkelhon]

Thanks!

[@PosthumanKindergarten]

nice! i had the same idea but (also looking at the comments here) i'm not the first (duh!), actually i was thinking of making a tesla coil that is tuned slightly above the frequency i want to use, and add a fairly long wire on top of it, reducing the tuning, this to transmit in medium waves, and with a wire long like 10 meters max... according to what other people did this will not cut it, but it will output some bits of electromagnetic, probably making a 10-20% of efficiency if lucky

[@DavidSkelhon]

It will definitely radiate power but efficiency would be low and difficult to measure accurately. If it isn't driven by a pure sine wave it will radiate a lot of RFI.