I don't have a thf6a but do have Kenwood thg71a which has an sma
connector.
I was told by a technician fairly knowledgeable about such things that
the sma isn't relaly meant to be a freuqnelty detached connector.
I've got sma to bnc adapters so I can use the coax in the van or on
my 2 meter j pole when I finally get it in the air. HOwever, I only
will remove the duck from the radio in a true emergency situation.
OTherwise, I understand the desire to try different antennas. I'd
find some way of leaving the bnc to sma adapter in place on your radio
and be careful and gentle being sure not to put undue force on the sma
connection when you attach different antennas.
73 de kb0ruu/5
Richard Webb
Electric Spider Productions
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
--- Benjamin Franklin November 1755