US via Pan Am Clipper to meet with the US I Troop Carrier Command. They started production of a number of versions of the Mk. III as the AN/PPN-1 (Eureka), AN/PPN-2 (Portable Eureka) and AN/TPN-1 (Transportable Eureka). The AN/APN-2 (Rebecca), also known as the SCR-729, used a display that saw use for a number of purposes. When many British military gliders failed to reach their landing zones in Sicily even in excellent conditions, a rushed effort to develop an even smaller and lighter Rebecca III system started. Cossor was again selected for the development, using a super-regenerative receiver and batteries for only 30 minutes of operation. The Rebecca IIIN version was used for strike aircraft in the Pacific theatre. These versions used capacitors in all five positions of the rotary switch. The introduction of the miniature B7G tubes in 1944 led to a new round of development of the Rebecca/Eureka. Dozens of different variations were eventually developed. Description The airborne Rebecca interrogator transmitted a 4-5 μs (microsecond) long pulse at a rate of 300 pulses per second on a frequency between 170 and 234 MHz. Upon receiving this signal, the Eureka rebroadcast the pulses on a different frequency. The Eureka unit also included a keying system that periodically lengthened the pulses over a period of seconds, allowing a morse code signal to be sent for station identification. This rebroadcast signal was received by two directional yagi antennas on the aircraft carrying the Rebecca unit, the usual location for the aerials being on either side of the aircraft cockpit. The signal was then sent to a conventional ASV radar display, with the vertical axis measuring time (and thus distance) and the horizontal showing the strength of the signal. If the aircraft was approaching the Eureka from the side, the horizontal pulse would extend further on one side of the display than the other, indicating the need for the aircraft to turn toward the shorter blip in order to fly directly toward the Eureka. There was a slight delay in the Eureka between signal reception and the return pulse. As the Rebecca units approached the Eureka the return signal would eventually overlap the interrogation pulse, and render the system ineffective. This occurred at a range of about two miles. At this time the crew had to switch to visual means of locating the drop zone. Reliance on Eureka without visual confirmation invariably