Hi XLF
Great stuff Stefan. I save it to show to a neighbour, just in case they say I’m crazy ;-)
I assume you are not using a resonant antenna at 80Hz, right ?
So, no coil. Just the inverted L element and ground at the HV transformer secondary ?
Mmmm. I have a similar device around which was the spark generator of an oil heating boiler
Wait for you at DC
73 de Luis
EA5DOM
Dear SLF friends,
A new step forward towards DC: Since yesterday 22:30 UTC i'm TXing a carrier at
80.005 Hz. That's the 3750 km band, where the far field begins at a distance of 598 km.
The antenna voltage is just 5 kV and i'm getting 1.2 mA antenna current, giving an
ERP of 20 fW (2E-14 W).
The voltage is even higher than in my recent experiment on 270 Hz, anyway the S/N is lower, indicating that my RX lacks of sensitivity. Indeed this experiment helps to estimate the lack of sensitivity. Looks like i'm missing about 10 dB on that frequency. Anyway
the signal is making the path of 3.5 km to my tree grabber, as usual shown at
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html. Not a big distance but still well beyond most garden fences!
The signal leaves a barely visible trace in the ZEVS window which is running at 3.8 mHz FFT bin witdh. Unfortunately ZEVS is off the air since a week or so. actually i wanted to transmit side by side with ZEVS, of course a bit deeper even.
>From a quiet period at night, i calculated the SNR of a 1 hour carrier period using vlfrx-tools: carrier
S/N: 16.83 dB in 277.8 uHz, -18.73 dB in 1Hz
For the crazy homebrewers i'd like to share that website where i ordered the HV-transformer,
http://www.hosin.de/Specials/HV-Trafo/hv-trafo.html A nightmare for all safety-fetishists! For the completeness it must be mentioned together with that page:
http://kurts-werkstatt.de/hv-trafo.htm
73, Stefan
