The Antex SRX‑3 is a triple‑zone Sirius/XM satellite radio tuner designed for home and office installations, featuring three independent audio outputs (RCA/optical), RS‑232 control, and preset storage per zone. Common failure points in this class of multi‑zone receivers include degraded RF antenna connections, failing power supply modules (especially the 12 V DC regulator), and defective internal logic boards that lose signal or lock up during channel changes. Begin troubleshooting by verifying the unit’s main power supply voltage with a multimeter, inspecting all antenna and cable connections for corrosion or loose contacts, and checking the RS‑232 port for proper handshake signals; if the tuner still fails to initialize, review any displayed error codes on the front panel and perform a factory reset per the user manual.[oss-gpt-20b]