I see you have asked this question in several places. I have read some
for what they are worth.

The Japanese manufacturers seems to have gotten a mind about a JIS for an
'equivalent' connector. I don't know this for sure, but I have come
across some incompatible look alike connectors on some well known
Japanese brand high power amplifiers.

Your Chinese parts may have been copied from one of these incompatible
connectors.

Owen


The problem of metric PL259's is well known in the UK at least , and
adaptors and 'metric' connectors are available from Ham Radio dealers.

73
Jeff