Hammond 148T 500 CT:3.2 Ohm PCB Output Transformer, 300 mW

The 148T is a small open frame output transformer that couples a 500 ohm center-tapped primary to a 3.2 ohm secondary. It is aimed at builders of low-power audio output stages that drive a 3.2 ohm load directly from a printed circuit board, such as compact speakers or earpieces in small equipment.

Like every unit in the 148 Series, it uses an economical, open type, horizontal bracket construction with pin-type terminals (0.25" length and 0.025" square) for P.C. board mounting. The windings are bifilar wound for balanced capacitive and resistance characteristics on pin bobbins that suit a standard 0.2" grid, and each unit is insulation tested at 250V rms. Pins are not labeled on the part; a dot marks pin 1 and the remaining pins follow the schematic figure.

Output is rated at 300 mW. For output transformers such as the 148T, the 2.1 mA current figure is the maximum unbalanced primary current. D.C. resistance is 41 ohms on the primary and 0.34 ohms on the secondary (+/- 15%). Frequency response is 200 Hz to 15 kHz (+/- 1 dB, referenced at 1 kHz) and insertion loss is less than 1/2 dB, while total distortion is approximately 1% at 200 Hz for outputs, decreasing at higher frequencies. Pin assignments follow schematic figure 4.

Net weight for the 148 Series is 0.6 oz. and the 148T shipping weight is 0.05 lbs (0.02 kg). The part is RoHS and REACH compliant, UPC 623980198507.