[Amps] Topics about Class A amplifier

[Hsu]

a) Anyone have experience to modify his transceiver's final to Class A mode  as FT-1000MP MK V?
  I think if we haven't good enough driver, the external Power amplifier cann't be have good 3rd IMD
 performance, especially for tetrode amplifier.
b)I'm planing to build an antenna muti-coupler for my 20 receivers.( similar ROHDE/SCHWARTZ NV-14T(http://bama.edebris.com/manuals/rohdeschwarz/nv14t/, MF-HF range)But 
R/S's design seems unmodern. I want to know anyone knows about hybrid-model or MMIC  for this application?the antenna multi-couple only have 0db power gain
 , but with very good reverse  isolation and very large dynamic range/3rd IMD performance.
I find out some models, for example MHW591/592, but these model's gain are too more(more than 35db). Any guys  knows more information about the appropriate Hybrid model/MMIC?
 Thanks in advance!
            73!Hsu