Transponder

A transponder (Wiki) "is a device that, upon receiving a signal, emits a different signal in response."

Secondary surveillance radar (Wiki)

Transponder: Rx: 1030 MHz, Tx: 1090

IFF Identification Friend or Foe (Wiki:IFF) "It uses atransponderthat listens for aninterrogationsignal and then sends aresponsethat identifies the broadcaster."

This key idea is that the interrogation signal needs to be something the enemy can not easily generate. If the enemy found a way to trigger a transponder response then that response could be used to target that vehicle. One way that was done was usingcode wheelsthat might be changed on a daily basis to modulate the interrogation signal.

This compatible with Secondary Surveillance RADAR (Wiki). The British Mk I IFF system was developed in parallel with the first Plan Position Indicator (Wiki,Ref 6-pg58) Louis Alan Hazeltine (Wiki) - Hazeltine Corporation (Wiki) - Neutrodyne (Wiki) - Hazeltine Corp made Radio & Television sets.

US NAVY MILITARY RADIO AIRCRAFT TRANSPONDER RT-82/APX-6

The APX-6 was the first widely used IFF transponder, and the first large application of lighthouse tubes. It could receive double pulses between 960 and 1150 MHz, and repliedwith single or double pulses, depending on the setting of the cockpit control panel.

This is the RT82/APX, introduced in WWII. The self-oscillating transmitter consists of a singlelighthouse tube2C42with an incredible pulse power output of 1kW at 1000MHz.With a maximum duty cycle of 0.0025, the average output was 2.5W The Transmitter 2C42, local oscillator 2C46, and the antenna tuned circuit each have a hand-tuned cavity in the combined tuning head. The relation of dial setting versus frequency in my unit is here. The circuit diagrams for this unit are APX6RF circuits and power supply APX6 Codec.

THIS ITEM IS BEING SOLD AS A COLLECTOR ITEM, A HISTORY RELICS, AND BEING SOLD AS IS. IT NOT A FUNCTIONAL UNIT.