this is what I am thinking,
then you can use plungers with a texture
it would probobly be better if you made your own 'hard line', which I thought about also, to house the plunger with better impedance match, but then you need to bond it to regular coax anyway , not sure how much difference is, but it should give lower DC resistance I think with plungers
Hmm, what I wanna find now, is the LMC400 hard line
maybe one of the other LM cables has a center conductor that will snug fit the pin. i need to look at the specs, if the center pin can be replaced with a plunger then you can just cut away the outside of the connector to get a real nice thing going without any BS
people with high speed VNA might have to do more work, but I only go to 300MHz, so I can use alot of different cables