Hammond 106T 100 CT to 8 Ohm Output Audio Transformer, 1.5 W

The 106T is a miniature 106 Series output transformer that couples a 100 ohm centre-tapped primary to an 8 ohm secondary. It is designed for compact audio output stages that drive 8 ohm loads directly from a PC board.

Rated output is 1500 mW with 1 dB insertion loss and a -1 dB low frequency roll-off at 170 Hz; the drawing specifies ±1.0dB from 170Hz to 20KHz at 20dBu. Maximum primary DC is 22 mA. Table DC resistance is 4.4 ohms primary and 0.7 ohms secondary (+/- 15%); the drawing lists 2.214 ohms (pins 1-2), 2.209 ohms (pins 2-4) and 0.670 ohms (pins 5-8). Across pins 1-4 the primary measures 140.42mH, 1.283K ohms, with 756.5uH leakage inductance at 1V, 1KHz.

Construction is rugged black epoxy potting that produces a completely sealed unit able to withstand severe environmental conditions, including those of MIL-T-27 (Grade 5, Class S). Centre-tapped windings use a bifilar technique for balanced resistive and capacitive characteristics, and the series carries a peak working voltage rating of 200V. The drawing also lists 500V RMS dielectric strength, a 105°C temperature class and a maximum operating altitude of 50,000 ft.

It mounts directly to a printed circuit board on square pins (0.025" square typical); where a connection is not used, no pin exists. It is REACH and RoHS compliant. Figure 8 gives the mechanical outline. Drawing weight is 1.44 oz.; shipping weight is 0.09 lbs (0.04 kg).