English: 8-12 GHz tunnel diode amplifier manufactured by Aertech, used in aerospace applications. This is a two-stage amplifier. Each stage consists of a reflection amplifier made of a biased negative resistance tunnel diode and a circulator, a three-port ferrite device that separates the output signal from the input, and matching networks. The input signal to each device is applied to port 1 at bottom of its heat sink, and is transferred to port 2 at right, connected to the tunnel diode mounted in the heat sink. The output from the tunnel diode emerges from port 3 at the top of the device. The circulator provides about 20dB isolation of the output from the input, so the gain of each stage must be limited below this value to prevent feedback, requiring 2 or more stages to achieve significant amplification. More information on these amplifiers is on Brooke Clarks Aertech website