500 W rotary spark gap transmitter

DSC_3954ac by Hal Kennedy on Flickr!

Replica of a 1/2 kW synchronous rotary gap transmitter. The original was designed circa 1910. It is firing at 1800 arcs per minute. Current in the arc is approximately 1,000 A.

This image by Hal Kennedy, N4GG was "Photo of the year" in QST magazine, and used in the 2011 ARRL annual calendar.

High resolution image on Flickr!