21 Apr 2023

VLF earth-mode TX


Looking back over some of my old photos, I came across this photo of my 5W earth-mode VLF transmitter, that was last used over 10 years ago. 

The 3C90 toroid on the left is to match the low impedance output from the TDA2003 to the earth-electrode "antenna" in the ground. In the centre is the TDA2003 audio amplifier. On the right is the keyer IC that can produce QRSS or CW.

It would be good to do some more experiments in the future, if my health allows.

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