This is almost the real deal 360 watt early SVT tube.
These work in everything from hybrid transceivers to my old 6146B SVT. I am not sure why Ampeg reverted to using the 6550 and knocking 70 watts off their output. The 6146B works well for RF, AF and modulation tasks. Shuguangs are not as good as the USA NOS tubes, but what is? I get about 320-330 watts from a sextet in an SVT. RCA's 6146B compliment gave me just over 360 watts. Shuguang's quality is inconsistent, but it seems less deliberate than other manufacturers. There is no BS hype in marketing, just a decent price.