Variable Inductor

I have 4 of these removed from Collins 208U linear amplifiers. This is 0.1 - 8.0 uH, and can handle 200 Amps RMS of RF. The weight is about 20 pounds of copper with silver plate. The outboard series trap is to suppress a 19 MHz spur from the transmitter.

This Big-Daddy pancake inductor is $250.00

Variable Inductor

I have 2 of these removed from Collins 208U linear amplifiers. With the full inductor in effect, the inductance is 8 uH. I'm using one of these and one of the vacuum variables in my own HF antenna tuner.

The inductance is 0.3 - 18 uH, and can handle 30 Amps RMS of RF. The material is silver plated copper.

The cost is $200.00

Pair of Air Core Inductors

The long inductor is 108 uH using copper wire.

The short inductor is 3.3 uH of aluminum conductor.

Safety Choke

This inductor from a Collins 208U 10 kW amplifier was the safety inductor used to insure that the antenna output stays at DC ground potential.

The wide spacing top end was connected to the 50 Ohm output of the amplifier, and the tightly wound end was at ground potential. If the 2000 pF coupling capacitor from the plate of the 4CX10000D were to become leaky, this inductor passed the DC to a sensor at the ground end, which shuts down the entire transmitter. The inductance is 40 uH.

Inductor with RF Relay Mounted in End

The inductor is tapped, and selected with the Jennings vacuum relay in the end. Removed from a Collins automatic antenna tuner.

Parallel Tank

The inductor is xxx uH.

The capacitor is yyy pF.