Hammond 276X 150VA 640V C.T. Plate & Filament Transformer

The 276X is a 150 VA plate and filament transformer built around a 640V centre-tapped high voltage secondary rated 172 mA, with a 5V C.T. filament winding at 3A and a 6.3V C.T. filament winding at 5A. Its lower plate voltage and higher plate current make it a fit for tube amplifier power supplies running from a 115 VAC, 60 Hz North American line.

Mechanically, the 276X is an enclosed, 4 hole, chassis mount design in the vertical ("X") mounting style, with minimum 6" long leads. Ordering-table dimensions are A 3.13 in (80 mm), B 3.50 in (89 mm), C 3.81 in (97 mm), D 2.50 in (64 mm) and F 2.19 in (56 mm), and the mounting slots measure 0.20 x 0.38 in (5 x 10 mm). The shipping weight is 5.2 lbs (2.36 kg).

Hammond states that 200 Series units can be run full wave bridge or full wave C.T., use Class A insulation (105 degrees C), are Hi-Pot tested at 2,000V RMS and are CSA certified (209651). The part is listed as REACH compliant and RoHS compliant.

The 276X primary is rated 115 VAC, 60 Hz. Following the August 2009 primary-winding running change, the series notes describe White and Gray leads for 115 VAC input (tape the Black), or White and Black leads (tape the Gray) where roughly 125V line voltage pushes the secondary too high. Never connect power to both the Gray and Black wires, which the manufacturer warns will destroy the transformer.