Silver solder 10% Mundorf - 100gr / 17m
Mundorf's Supreme Msolder welding wire is composed of 10% silver. It is indicated for advanced projects that require excellent conductivity (mounting tubes, cable assembly, silver / gold foil). The silver content is balanced by a flux ratio of (2.2.3).
Caution, melting point is 290°C / 554°F, which implies the need of a good soldering iron.
If you do not need the whole coil, you can find a part (2m /11.7g) here