Ladder line Quick connections

[VK5ZD]

The physical closeness of the pairs of DPDT relay contacts within a single relay unit would not retain the 450 ohm characteristic impedance of the open wire line.

You could use two relays spaced the right distance apart. Automotive relays would probably do if you don't mind keeping the coils energised.
Another option would be to use just the centre pin of 2 standard connectors (e.g. BNC, N, etc.) if you prefer something that can be physically disconnected.