RADAR KILOVOLTER HIGH VOLTAGE METER, 1950's

For measuring high voltages, probably a TV tubes high tension, the probe on the left is held on the voltage output to be tested, after the lead is connected to ground.
By adjusting the knob on the right the distance between the two balls is reduced untill the voltage sparks accross the gap, the voltage is then read from the scale.

Your comments:

• I have one of these. It belonged to my father who is now deceased. He used to mend TV's in the 1960's / 70's
  .......... Susan Ling, Norwich, 3rd of November 2015
  
  
• I used to have one of these and you don't wind it in until you get a spark to measure the voltage, you wind it in to get a spark and then wind it out until the spark just extinguishes and then take that reading it is the voltage at zero load
  .......... John Penna, Epsom Surrey England, 20th of August 2010
  
  

A0274