The 850NA is a broadcast-quality sealed audio transformer designed for output-to-line matching or interstage applications. It features a deep-drawn steel case with tin-plated finish, sealed construction with wax-potted core, and balanced split windings on both primary and secondary for circuit versatility. The transformer delivers a wide frequency response of ±0.5 dB maximum from 20 Hz to 20 kHz, with an insertion loss of approximately 1 dB and maximum power level of +15 dBm under specified characteristics. Distortion is approximately 1.5% at 20 Hz under full power, and an electrostatic shield between primary and secondary (connected to the green lead) provides humbucking construction for noise rejection. This transformer is ideal for professional audio broadcast applications requiring impedance matching between output stages and line-level inputs, or for interstage coupling in audio signal chains.