What type of wire would connect an SSB automatic tuner to an insulated backstay?

The connection between an SSB (Single Sideband) automatic tuner and an insulated backstay typically requires a cable that can handle high voltages and is designed for RF (radio frequency) applications. GTO-15 high-voltage cable is specifically designed for use with antennas and tuners in amateur radio setups, making it the most suitable choice in this context.

GTO-15 can handle the high voltages found in RF transmission and is flexible enough to accommodate the specific needs of an outdoor installation. Additionally, it is built to minimize loss and resist environmental factors, which is important for maintaining signal integrity over longer distances.

Other cable types mentioned, such as RG-58 coaxial cable, while commonly used for RF transmission, may not be ideal for direct connection to a high-voltage tuner in the context of an insulated backstay. Speaker wire and Cat 5 Ethernet cable also do not possess the necessary characteristics for high-frequency RF applications and would not be suitable for such connections.