[amsat-bb] Question re rx/tx relays and diplexer

Good Afternoon All:

I am working on packaging and interconnections for a mast-mounted unit for my 70cm system.

My plan now is to place the preamp, a diplexer, and t/r relay all inside a single aluminum box.

In and out will be N connectors.

Internally, I am thinking of SMA links and pigtails.

My 70 cm rig can produce a maximum of 35watts right now.

Do commercial coaxial relays for t/r use short the rx line when in tx? or do they leave it float?

Also, should the 2M output on the diplexer for desense be terminated? or left open.

Finally, what type small coax would be appropriate for use inside this box between modules?

Main feedline is LMR400.

Thanks

Curt KU8L