RG11 cables are often used for long-distance runs and high-frequency applications because of their low signal loss. Here’s a breakdown of how they can be applied for main lines and connecting an amplifier to a splitter:

1. Main Lines: RG11 cable is an ideal choice for main cable lines (or backbone lines) in situations where you need to cover long distances without signal degradation. Due to its thicker gauge and better shielding, it can maintain a strong signal over much longer runs than RG6, for example. This makes it well-suited for connecting from a central distribution point to multiple areas or from the main line to several splitters.
2. Connecting an Amplifier to a Splitter: RG11 cable can also be effective for connecting an amplifier to a splitter, especially if you’re dealing with distances longer than 50 feet or in setups where minimal signal loss is critical. However, because RG11 cable is bulkier and less flexible than RG6, it’s often reserved for longer stretches, while RG6 can handle shorter connections between the amp and the splitter in most home installations.
3. Installation Considerations: Given its thickness, RG11 cable may be more challenging to install in tight spaces. Ensure that connectors are properly suited to RG11’s size, as it uses F-type connectors but requires specific RG11-compatible ones due to its larger diameter.

In summary, RG11 cable is generally best for the main lines or long runs where signal retention is essential. For shorter connections, consider using RG6 unless the environment or application demands RG11’s superior signal handling.