Hammond 146D 100CT to 3.2 Ohm Output Audio Transformer, 700 mW

The 146D is a compact open-frame audio output transformer with a 100 ohm center-tapped primary and a 3.2 ohm secondary, rated for 700 mW. It is part of the 143-146 Series of chassis-mount audio transformers and suits engineers, technicians and OEM builders driving a low-impedance 3.2 ohm load from a small output stage.

The primary is rated for 14 mA of D.C. current, and the series table lists D.C. resistances of 4.4 ohms primary and 0.3 ohms secondary (+/- 15%). The drawing gives typical values of 4.583 ohms blue-brown and 0.288 ohms black-green D.C. resistance (the series table lists 4.4 and 0.3 ohms, +/- 15%), 500V RMS dielectric strength, 634.6 mH primary inductance and 775.4 ohm impedance at 150 Hz, 5.0 V open circuit, and 945 uH leakage inductance.

Construction is small, economical and open, on a two-hole horizontal mounting bracket, with insulated, color-coded flexible leads. The part drawing specifies leads 5 in long minimum (the series sheet lists 3 in minimum for the 146 Series) and a weight of 1.3 oz; the primary uses blue and brown leads with a red center tap, and the secondary black and green. Frequency response is 150 Hz to 15 kHz (+/- 1 dB, reference 1 kHz), and the drawing lists a temperature range of -40 to 105 degrees C.

Overall dimensions from the series table are A 1.63 in (41 mm), B 0.88 in (22 mm), C 0.81 in (21 mm) and D 1.38 in (35 mm). When operating below nominal impedance, power capability and frequency spectrum are proportionately lower, and higher at higher impedances. The 146D is RoHS and REACH compliant; for PC board mounting the manufacturer refers to the 148 and 149 series.