MHz) or 1.5 m (200 MHz), each with a peak-power of only 5 kW. The lower power significantly reduced the range. About 50 sets of all versions of these systems were built. Another similar system was the Type 21. Fundamentally, it was the 200-MHz version of the Type 12 redesigned for shipboard use and weighing only about . The first sets were installed on the battleships and in April 1942. About 40 sets were eventually built. In this same time period, the more use-flexible Type 13 was also being designed. Operating at 2.0 m (150 MHz) and with a peak power of 10 kW, this set included a major advancement. A unit duplexer had been developed to allow the use of a common antenna. With a weight of (a small fraction of that of the Type 11), this system could be readily used on shipboard as well as at land stations. Its detection range was about the same as the Type 12. It was placed into service in late 1942, and by 1944 it had also been adapted for use on surfaced submarines. With some 1,000 sets eventually being built, the Type 13 was by far the most used air- and surface-search radar of the Imperial Navy. The Type 14 was a shipboard system designed for long-range, air-search applications. With a peak power of 100 kW and operating at 6 m (50 MHz), this weighed . Only two of these systems were placed in service in May 1945, just at the end of the war. The Imperial Navy built two radars based on the captured SCR-268. The Type 41 was electronically like the original, but with two large dipole array antennas and configured for shipboard, fire-control applications. About 50 of these were built, and it went into service in August 1943. The Type 42 had more revisions, including a change to using four Yagi antennas. Some 60 were built and put into service in October 1944. Both systems had a range of about 40 km. The NTRI made minimal changes to the 60 cm (500-MHz) Würzburg, mainly converting the oscillator from vacuum tubes to a magnetron. The result was the Type 23 anti-ship, fire-control radar intended for cruisers and larger ships. With the change to a magnetron, the output was approximately halved to a peak-power of about 5 kW; this gave a range of only for detecting most surface ships.