Hammond 125H 8 W 10K CT Push-Pull Output Transformer, 2/4/8 Ohm

The 125H is an 8 watt general replacement push-pull tube output transformer with a fixed 10,000 ohm centre-tapped primary and a secondary tapped for 2, 4 or 8 ohm speakers. It is designed for general purpose or replacement use (not Hi-Fi) in push-pull tube output circuits, and is a straightforward choice for technicians restoring radios and small amplifiers that call for a 10K plate-to-plate load.

Compared with the universal 125A-125E range, the 125H offers fewer impedance options in a smaller unit. Its secondary solder lugs are marked #1 COM, #2 2 ohm, #3 4 ohm and #4 8 ohm, so connecting the speaker simply means choosing the lug that matches the voice coil. Primary leads (BLU plate, RED B+, BRN plate) are at least 5 inches long.

The ordering table lists a primary inductance of 5.60 H. Typical drawing data shows 194 ohms primary DCR (blue - brown), 3.63 H primary inductance and 21.0 kOhm primary impedance at 1 kHz, 1 V, with secondary DCR of 117, 178 and 263 milliohms for the 2, 4 and 8 ohm taps. 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.

The 125H is open style and measures A 2.81 in (71 mm), B 1.00 in (25 mm), C 1.63 in (41 mm) and D 2.38 in (60 mm), with 0.19 in (5 mm) mounting holes. It weighs 0.55 lbs (0.25 kg), is made in Canada and is RoHS and REACH compliant. For single ended stages the manufacturer points to the 125SE Series.