Hammond 279X 186VA 850V C.T. Plate & Filament Transformer

The 279X is a 186 VA plate and filament transformer offering an 850V centre-tapped high voltage secondary at 172 mA. Filament windings are a 5V winding at 3A (not centre-tapped) and a 6.3V C.T. winding at 5A. It is designed for tube equipment powered from a North American 115 VAC, 60 Hz line where a higher plate voltage is needed.

Mechanically, the 279X 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 4.00 in (102 mm), C 3.81 in (97 mm), D 2.50 in (64 mm) and F 2.69 in (68 mm), and the mounting slots measure 0.20 x 0.38 in (5 x 10 mm). The shipping weight is 6.7 lbs (3.04 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 279X 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.