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Re: Newbie Question



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Ed,

Its interesting what can happen when a plasma is created. A secondary strike to the primary can make the secondary more lethal.

Gerry R.


Original poster: Ed Phillips <evp@xxxxxxxxxxx>

Dennis,
I was running  my coil in the garage and was getting a few strikes to the
ceiling. Evidently it entered a wire and went inside the house and traveling
many feet burned a 12 gauge insulated wire in two at a wall socket. Also
fried the answering machine hooked to the socket with an AC to DC wall
transformer.

Brad McPeak"

Very small correction. It wasn't the current from the strike itself which burned the wire, but the line current supplied when the wire arced over at that point. Lot more current and melting power than in the streamer. This was apparently a very common problem in the days when hams used high-power spark transmitters (most guys ran at least a kilowatt line power) and they reported all kinds of such problems which were called "kick back". One of the commonest ones for some reason was melting down of light sockets. The stories report molten brass dripping out of the socket and onto the floor, but I suspect that's a bit of an exaggeration. One of the partial fixes was known as "kick back preventer" and put capacitors across the power lines. In the case of the ham problems there weren't streamers striking the lines but there was inductive and capacitive coupling from the antennas, which tended to be quite large. Turns out that the peak powers transmitted were in the megawatts, as with TC's. A typical "high power" station used an 0.01 mfd storage capacitor charged to 25 kV and discharged through a synchronous rotary gap. At the operating frequency of 1500 kHz the primary tuning coil was a single turn of heavy copper strap or bar, less than a foot in diameter, and inductively coupled to the antenna loading coil. The resulting antenna current was of the order of 7 to 10 amps, as read with a thermocouple or hot-wire ammeter.

Ed