In RF systems, connectors almost never get blamed first. When something drifts, engineers look at active devices, calibration data, firmware timing, or environmental noise. Adapters sit quietly in the background, usually added late, often undocumented, and rarely questioned once the signal appears to pass. That’s exactly why they matter. A small mechanical transition can introduce an electrical discontinuity that doesn’t break the system outright, but slowly eats into margin. This guide focuses on how to place and manage that transition deliberately so it stays predictable across lab benches, field diagnostics, and long-running installations.