Since solder is such a poor conductor, why use it?

if you are not happy with solder then you could always try conductive epoxy! Drying time might be the only issue :)

For me, silver solder is fine and it seals against oxidization, just ensure that the pieces being soldered have a good connection and try not to use too much solder. Also, using a good flux paste ensures good eutectic flow :)

Electron tubes are not soldered into place. All those ribbon connectors are not soldered. Why not use tiny little mechanical connectors instead of solder? Has anyone actually measured the losses due to all the solder connections? One wonders how much it could be and compared to what.

Wire wrap connections...

Almarg, I doubt seriously if the solder you and I have access to is anything like that used in the military.

Mapman, a linear amp doesn't solve the problem but could afford the welding of wires.

Almarg, I doubt seriously if the solder you and I have access to is anything like that used in the military.

Tbg

I spent 20 years as an electronic tech in the USAF and there was nothing special about the solder we used. Yes I was soldering components on boards as well as connectors used in aircraft. Now maybe NASA uses something special, but I doubt it.
A good solder joint is going to last. It just has to be done properly. That's what quality control is for.