Follow up with new data:There was a write up by Rad Lab engineer Roger Wilkinson in 1946 on Japanese radars in the AIEE Journal.
Wilkinson reports that the Japanese designation system was so complex that Japanese themselves could not even keep it straight. The Mk2MOd2 radar was simply refered to as the 22 or Type 22. There were two improved Type 22 radars being developed at the end of the war. There was the Type 220 which was an improved 22 for surface search and an improved Type 32 for firecontrol. The range had been increased from 25km to 35 km. The Type 32 was like the Type 22 but it had two receiving horns instead of one, while retaining the single transmitting horn. The two horns were for conventional Lobe Switching. The lobe switching in this case provided a bearing accuracy of 0.5*, well inferior to Anglo American and German standards.
Wilkinson's data for Type 22 are:
Transmitter was a water cooled M-312 Cavity Magnetron
producing an max output of 6kw (the Japanese did not discover strapping). A 11,000 volt pulse was delivered to the cathode of the magnetron by a pulser.
The receiver was superhet with a crystal mixing diode and an M60-S split anode magnetron for local oscillator. The IF was 14.5mhz.
There were three A-scope indicators. One was the bearing indicator for maximizing signal or in the case of type 32 for matching the pips of the split beams on receive. There was a coarse range display with the time base in 5km increments extending out to 60km. There was a fine range display with range gates of 1,000 meters. It was very similar to the Precision Ranging Panals used on British radar sets of the period. The pip was moved so that the leading edge of the pip lined up with a line across the middle of the scope by a hand crank. The range accuracy on all models was 100 meters at all ranges to target.
The transmitted beam width was 15*. On the Type 32 each received beam width was 6*.
The pulse width was 10 micro seconds.
This helped it to obtain BB to BB ranges of up to 35km with 6kw of power or 25km with 2.5kw of power of the earlier models. The submarine mounted version could obtain a range of 10km to a battleship from a surfaced submarine. The long pulse width resulted in an illumination energy of 60kw or 25kw. Another aspect of the long pulse width was no need for high band width, which increases receiver sensitivity. The long pulse width would have resulted in a range resolution of 1500 meters if conventional methods were being used.
Wilkinson reports that a Type 22 was set up overlooking Tokyo Bay for the US Army. They were amazed at how fine the diffinition was. How did the Japanese pull this off with a ten micro second pulse width?