This paper specifies LOGOS Core, a conversion–and–stability module designed to harvest usable electrical power from a measured broadband electromagnetic port spectrum associated with deuterium–fusion environments, and to convert that harvested power into (i) conditioned electrical output and (ii) fast stabilization actuation power. This document is the product of informed scientific imagination. No claim is made that the system described herein is technologically feasible, constructible with present engineering, licensable, commercially realizable, or physically achievable at any time. No claim is made that Unified Substrate Theory (UST) creates energy or violates thermodynamics. UST contributes architectural priors only: discrete–scale organization in logarithmic coordinates motivates a log–periodic resonant ladder for broadband impedance matching, with β–discipline treated strictly as a commissioning–tested hypothesis; and an AEGIS–style self–strengthening sheath is formalized as a verifiable overload–control law that converts irreversible overload deposition into increased damping and bounded operation. The paper is intentionally standalone and procurement–oriented: it defines measurable input power spectral density Sport(f), explicit RF harvesting and impedance matching, resonant capture, rectification, DC combining, bus conditioning, overload protection logic, latency and thermal constraints, falsifiers, and acceptance tests. A parameter–closed worked engineering instantiation is included to demonstrate closure from spectrum to component stresses. For fuel–scale intuition only, ideal complete D–D fusion burn of 1 kg deuterium corresponds to ∼ 8.7×1013 J, i.e. ∼ 2.4×1010 W sustained for one hour; all LOGOS Core outputs remain strictly bounded by the measured port power Pch = R Sport(f) df.