Hammond 143B 3.2 to 4000 Ohm Chassis Mount Input Audio Transformer

The 143B is an input audio transformer in the 143-146 Series, stepping a very low 3.2 ohm primary up to a 4000 ohm secondary. It is intended for input applications where a low impedance source must be matched to a much higher impedance circuit, and it mounts to a chassis rather than a circuit board.

The 143B is rated for 15 mW output, and the series table lists its primary D.C. current as 0 mA. D.C. resistance is 0.4 ohms on the primary and 245 ohms on the secondary, both +/- 15%.

Mechanically, the 143B is a small, economical open type transformer with a two hole horizontal bracket for chassis mounting and overall dimensions of A 1.26 in (32 mm), B 0.69 in (18 mm), C 0.69 in (18 mm) and D 1.06 in (27 mm). It uses insulated, color coded flexible leads at least 4" long, and net weight is 0.5 oz. Where a P.C. board mounted version of this style is needed, the manufacturer refers to the 148 and 149 series.

Frequency response is 150 Hz to 15 kHz within +/- 1 dB, referenced to 1000 Hz. The manufacturer notes that operating at impedances below nominal lowers power capability and frequency spectrum proportionately, while higher impedances raise them. It follows schematic 1 in the series table and is listed as RoHS and REACH compliant (UPC 623980190907).