The 850QA is a sealed broadcast quality audio transformer designed for interstage or isolating applications. It features balanced split windings on both primary and secondary with nominal impedance of 10K/40K ohms on each side, enabling circuit versatility and impedance matching. The transformer is housed in a deep-drawn steel case with tin plated finish and includes a sealed, wax potted core for stable characteristics and long life. It delivers wide frequency response of ±0.5 dB maximum from 20 Hz to 20 kHz, with insertion loss of approximately 1 dB and distortion of approximately 1.5% at 20 Hz under full power. The unit features an electrostatic shield between primary and secondary connected to the green lead, humbucking construction, and is mounted with two 6-32 studs. Its compact dimensions (1.7" × 1.2" × 1.65" high) and 0.4 lb weight make it suitable for professional audio equipment, broadcast systems, and high-fidelity audio applications requiring isolation and impedance matching.