I (accidentally!) had the misfortune of torturing the cat in the apartment directly above mine, many moons ago. I had built myself a simple modem for packet ra

I (accidentally!) had the misfortune of torturing the cat in the apartment directly above mine, many moons ago. I had built myself a simple modem for packet radio (ham radio; very slow modem for use on shortwave bands), and wanted to test it. However, I was at home, and at the time I used either the HF station I had installed at my office in the university or the one at the radio club down the hill. Heck, I'd only try some local comms, anyway. I got an old transmitter out of a cabinet and strung up a dipole antenna under the ceiling in the living room. I tied one end to the curtain rack either end of the room, called the radio club, agreed on a frequency, and off I went. When I keyed the transmitter, I could hear a commotion starting upstairs. It died down, and I didn't think more of it. After a while, new commotion. Next day, I met the occupant of the apartment above at the mailboxes; she said her cat had acted up last night - running around the living room like it had the devil on its back. Turned out it had a metal collar, and loved to snooze on the floor right under the window, as the radiator on the wall below the window made it real warm and cozy there. When I keyed the transmitter, I basically had a very high RF voltage at the end of the antenna - and the cat, whose collar was a mere few centimeters away, got enough of a current induced in it for the cat to go ballistic. Poor thing.