It is counted some of the radars of the series KLJ-n is based on the the radar AN/APG-66, is certain that?
Which of them is the most seemed one to the AN/APG-66?
None of them.
That's the problem of conventional wisdom from "experts" that lack any electronic, electrical, computer engineering, IT, and software development background. They think you can copy or reverse engineer anything by looking at it.
Look at all the PC and notebook motherboards around and you will notice that despite the great variety in all their designs, they all work the same way. Because what you see on the outside is the least important of how it works inside. Even if China acquired brochures of the APG-66, or had engineers look at them from an F-16, it would tell you nothing about how it operates inside. Even by studying the developments of others, all it gives you are nothing but goals to aspire to, plus a few clues along the way. But you really need to sweat out the programming and internal diagram designs on your own.
From all the very limited information that has been put out so far, the KLJ series while successful, seems like a generic slotted array planar radar. It seems to have all the expected and basic functionality, such as RWS, TWS, TWS engagement, STT, boresight, vertical scan, gunsight, bombsight, ground mapping by doppler sharpening, plus a few others, like air to sea search, MTI/GMTI, and maybe but still arguable, SAR. Its resemblance to other fighter radars is only because these other radars now seem to be more and more generic, and the APG-66Vwhatsover (short of the latest model) is being held regarded as the epitome of genericness that others like Thales, FIAR, ELTA and Phazotron is using as a target.