Re: Newbie Question

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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