THIS GIANT CAPACITOR, a 200,000-volt air condenser with a capacity of 2,500 mmfd., is used as a phantom antenna for testing high-power transmitters. It has 12 hollow plates made of 16-gauge sheet steel and plated first with copper and then with nickel to improve conduction. Shields at the ends of each plate prevent dissipation of electricity. The supporting insulators were designed for a 400,000-volt dry flashover. Despite its 10′ height and 2,000-lb. weight, the unit can be moved easily on its casters or can be taken down completely or assembled in a single day. It was built by the Federal Telephone and Radio Corporation, and is used to test large transmitters at full load without radiating any signals.