spark gap transmitter in action

This breathtaking replica project — I’m too Youtube-primitive to figure out its creator’s name, or I’d give him well-deserved credit — shows what a ham station sounded like to its operator in about 1910.  This is ‘spark gap’ transmission.  Don’t confuse it with rotary spark transmission.  That was an innovation on this, a mechanical way to manufacture RF (‘radio frequency’) energy.  This is nothing more than a Tesla coil, whose arc causes radio noise, exactly the way lightning does.  Because their signals splattered across huge sections of the radio band, they were regulated out of existence quickly.

‘MESCO’ was an early supplier of amateur radio equipment, principally coils.  The condenser stack is small here.  Marconi’s transoceanic ones were the size of a small building.  There is a picture of this, in a superb paper, here, by Jack Belrose, VE2CV, explaining the physics that made spark work.  Marconi wasn’t sure what frequency (well, frequencies) he was transmitting on.  Nobody was very sure about their frequency, but it didn’t matter much.  The antennas were so out-of-tune, and often so overpowered, that they buzzed.  Kids could sit on your lawn of a quiet evening and copy your code from the arcing overhead.

Oh, the code here translates like this:


This is around 15 words per minute, slightly faster than average speed in 1910.

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Filed under the 19-teens

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