Hammond 275X 167VA 800V C.T. Plate & Filament Transformer

The 275X is a 167 VA high voltage (plate) and filament power transformer that pairs an 800V centre-tapped high voltage winding rated 155 mA with two centre-tapped filament windings: 5V at 3A and 6.3V at 5A. It suits builders and restorers of tube equipment who need a single enclosed unit to supply both B+ and heater circuits from a North American 115 VAC, 60 Hz line.

Mechanically, the 275X 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 3.75 in (95 mm), C 3.81 in (97 mm), D 2.50 in (64 mm) and F 2.44 in (62 mm), and the mounting slots measure 0.20 x 0.38 in (5 x 10 mm). The shipping weight is 5.8 lbs (2.63 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 275X 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.