Vintage CETC W1777 Hermetically Sealed Output / Feedback Transformer – Tested Good
Up for sale is a rare, high-quality vintage hermetically sealed audio output transformer manufactured by CETC, part number W1777 (290946), also stamped CET-40 INS-5 on the chassis side.
Featuring a dedicated 4V feedback winding (FDBK) and a voice/communications frequency range of 200 to 8,000 CPS, this heavy-duty component is beautifully built. It is an ideal find for vintage tube equipment restorations, amateur radio modulator projects, vintage communications gear, or industrial servo tube amplifiers.
Specifications from Case Stamping:
Primary Windings (Pins 1-2-3): Rated for 173V AC / 300V DC @ 0.140A DC (W.V. to Ground: 545V)
Output Winding (Pins 4-5-6): 110V Center-Tapped (CT) @ 0.077A
Feedback Winding (Pins 7-8): 4V (FDBK)
Frequency Range: 200–8,000 CPS (Cycles Per Second / Hz)
Insulation Rating: HIPOT 1.5 KV
Actual Bench Test Results:
Primary (1 to 2): 89 Ohms
Primary (2 to 3): 83 Ohms
Secondary Output (4 to 5): 30 Ohms
Secondary Output (5 to 6): 28 Ohms
Feedback (7 to 8): 4 Ohms
Ground Insulation Check: Verified completely open; no leakage or shorts to the metal case.
Outstanding physical shape for its age. Will be securely wrapped and padded to protect the bottom ceramic terminal assembly during transport.