China is equipping its 21 ton, twin engine, Y-7 transport with a phased array radar similar to that used on the larger KJ200 AWACS. The Y-7 is a Chinese copy of the Russian An-24. The Y-7 AWACS would be similar to the U.S. 23 ton E-2 that operates off carriers.
Four years ago, the Chinese Air Force realized it was not happy with its first four IL-76 AWACS (A-50s from Russia, converted to use Chinese KJ2000 radar systems). This led to a smaller system carried in the Chinese made Y8 aircraft (as the KJ200). Eventually, the Chinese began outfitting a Boeing 737-800 airliner as an AWACS aircraft. There may be as many as three of the 737 AWACS. These work much better. The Y-7 is thought to be a version that could operate off China's coming fleet of aircraft carriers. But the Y-7 is also cheaper, and better suited for equipping more air force units with AWACS capability.
The KJ200 entered service two years ago, and export versions sell for about $145 million each. China has had to develop its own phased array radar for it. The Y8 based KJ200 carries a flight crew of five and a mission (AWACS) crew of about a dozen. The aircraft can stay airborne for about seven hours per sortie. The KJ2000 radar has a range of about 300 kilometers, and the computer systems are supposed to be able to handle 5-10 fighters at a time, and keep track of several dozen enemy targets.
Meanwhile, the 54 ton propeller driven Y8 (which is based on the Russian An-12) and Y-7, and 157 ton Il-76 jet, are apparently considered less reliable, and more expensive to maintain, than the twin engine, 79 ton, Boeing 737-800. Chinese airlines (some of them controlled by the Chinese Air Force) have been using the 737-800 since 1999 (a year after this model entered service).