Hammond 148D 200K to 1000 Ohm Input Transformer, PCB Mount

The 148D is an open-frame audio input transformer for printed circuit boards that matches a 200K ohm primary to a 1000 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.

It has the highest primary impedance of the 148 parts listed here and a 0 mA maximum primary D.C. current rating. D.C. resistance is 1760 ohms primary and 6.2 ohms secondary (+/- 15%), output is 3 mW, and it is the part in this group drawn to schematic figure 3.

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 148D is RoHS and REACH compliant. For rugged epoxy cast units the manufacturer refers to its 102, 104, 106 or 107, 108 and 109 series.