for field operation; this project was also abandoned. The British GL Mk 2 was much less complicated than the SCR-268 and was easily reverse engineered; in addition, the notes on the SLC were available. From this came the Tachi-3, a ground-based tracking radar. This included many significant changes to the original British system; foremost were a change to a fixed-location configuration and a totally different antenna system. The Tachi-3 transmitter operated at 3.75 m (80 MHz), and produced about 50-kW peak power, with 1- to 2-ms pulse width and 1- or 2-kHz PRF. The transmitter was designed for enclosure in an underground shelter. It used a Yagi antenna that was rigidly mounted above the shelter and the entire unit could be rotated in azimuth. By phasing the antenna elements, some elevation change could be attained. The receiver for Tachi-3 was located in another underground shelter about 30-m distance from the transmitter. Four dipole antennas were mounted on orthogonal arms, and the shelter and antennas rotated to scan in azimuth. The maximum range was about 40 km. NEC built some 150 of these sets, and they finally entered service in early 1944. The follow-on project at Toshiba was designated Tachi-4. This was for a ground-based tracking radar, again using the SCR-268 as a pattern. Still with the original 1.5 m (200 MHz) operation, this set performed reasonably well, and about 70 sets were produced. These began service in mid-1944; however, by then the Tachi-3 was available and was superior in performance. Engineers at Toshiba had already begun work on a pulse-modulated system. With the arrival of the damaged SCR-270, portions were incorporated into the ongoing development of a fixed-site, early-warning system designated Tachi-6. The transmitter operated in the 3- to 4-m (100- to 75-MHz) band with a peak power of 50 kW. It used a dipole-array antenna atop a tall pole. Multiple receiver stations were spaced about 100 m around the transmitter. Each of these had a hand-rotated pole with Yagi antennas at two levels, allowing azimuth and elevation measurements. One receiver station could track an aircraft while the others were searching. Ranges up to 300 km were attained and shown on a CRT display. This went into service in early 1943; about 350 Tachi-6 systems were eventually built. A transportable version of this early-warning system was added. Designated Tachi-7, the primary difference was that the transmitter with a folding antenna