Hammond 148A 150/600 to 600/2400 Ohm Input Transformer, PCB Mount

The 148A is an open-frame audio input transformer for printed circuit boards, with a dual 150/600 ohm primary and a dual 600/2400 ohm secondary. It is part of the 148 Series of audio open-frame transformers and is aimed at designers and OEM builders who need a board-mounted input transformer in a small signal-level audio circuit.

Both windings offer two impedances, so D.C. resistance figures of 45 ohms primary and 300 ohms secondary (+/- 15%) are, per the series notes, for the total winding with multiple windings connected in series. It is rated for 1.9 mA maximum primary D.C. current and 300 mW output, and uses schematic figure 1.

The transformer uses economical, open-type horizontal bracket construction with pin terminals 0.25 in long and 0.025 in square for P.C. board mounting. Windings are bifilar wound for balanced capacitive and resistance characteristics, on pin bobbins for standard 0.2 in grid pin spacing. Pins are not labeled; a dot marks pin 1, and the remaining pins follow from the schematic. Net weight is 0.6 oz for the 148 Series.

Frequency response is 200 Hz to 15 kHz (+/- 1 dB, referenced at 1 kHz), insertion loss is less than 1/2 dB and the insulation test is 250V rms. The 148A is RoHS and REACH compliant. For rugged epoxy cast units the manufacturer refers to its 102, 104, 106 or 107, 108 and 109 series.