An inductor used in the output stage of a high power radio transmitter in a radio station in 1945. This is probably an antenna tuning inductance used to match the antenna to the transmitter. It shows high Q construction to prevent losses at radio frequencies:the conductor is made of large diameter tubing to reduce losses from skin effect, the turns are spaced apart to minimize losses due to proximity effect, and the coil is supported by narrow dielectric strips to minimize dielectric losses.