Hammond 125J 8 W 2.5K/4K CT Push-Pull Output, 10-Inch Leads

The 125J is an 8 watt general replacement push-pull tube output transformer with a selectable 2,500 or 4,000 ohm centre-tapped primary and a 6/8 or 3.2/4 ohm secondary. It is designed for general purpose or replacement use (not Hi-Fi) in push-pull tube output circuits, and suits service technicians and builders working with lower plate-to-plate loads.

Instead of solder lugs, the 125J uses open style construction with primary and secondary leads at least 10 inches long, which helps when the transformer mounts some distance from the tube sockets or speaker terminals. The hook-up data sets the impedance by which secondary leads you use (primary measured plate to plate, brown to blue):

• 4,000 ohm C.T. primary, 6-8 ohm speaker: WHT - GRN
• 4,000 ohm C.T. primary, 3.2-4 ohm speaker: WHT - YEL
• 2,500 ohm C.T. primary, 6-8 ohm speaker: BLK - GRN
• 2,500 ohm C.T. primary, 3.2/4 ohm speaker: BLK - YEL

The ordering table lists 5.60 H primary inductance. Typical drawing values are 170 ohms primary DCR (blue - brown), 6.45 H primary inductance and 39.2 kOhm primary impedance at 1 kHz, 1 V. Frequency response is 150 Hz - 15 kHz (+/- 1 dB max, ref. 1 kHz), dielectric strength is 1500 Vrms and the temperature range is -40 to 105C.

Overall dimensions are A 3.25 in (83 mm), B 1.50 in (38 mm), C 1.94 in (49 mm) and D 2.81 in (71 mm), with 0.19 in (5 mm) mounting holes; the unit weighs 1 lb (0.45 kg). It is made in Canada and RoHS and REACH compliant. For single ended designs, the 125SE Series is the recommended alternative.