Hammond 107B 150 CT to 12 Ohm Miniature Audio Transformer

The 107B is a 150 mW miniature audio transformer from the 107 Series with a 150 ohm centre-tapped primary (pins 1-3) and a 12 ohm secondary (pins 4-6). With a 3.53:1 turns ratio it steps a low-impedance line down into a 12 ohm load, and the series positions it for audio input, line matching and output transformer applications on a PC board.

Its power level is 150mw from 200 Hz. to 50 Khz. At +0 dbm and +10 dbm the frequency range is 150 Hz. to 80 Khz., narrowing to 200 Hz. to 80 Khz. at +20 dbm (all +/- 1.5db, measured with no D.C. saturation); the drawing also gives ±1.5db from 300Hz to 50KHz. Typical DCR is 22 ohms on the primary (10/10 ohms per half) and 1.85 ohms on the secondary, against table values of 20 and 2 ohms (+/- 20%). Primary inductance is 150 mH, secondary 14.5 mH, and leakage inductance 0.30 mH. Maximum D.C. unbalance is 12 mA, and dielectric strength is 100 Vrms.

Every 107 Series unit is epoxy potted in an attractive black molded case, and the rugged potting produces a completely sealed part that withstands severe environmental conditions. It will withstand soldering for 10 sec. at 260 degrees C, with a maximum ambient temperature of 85 degrees C; the casting epoxy has a workable range of -40°C to +105°C under a normal rate of change, not including thermal shock. Because the secondary has no centre tap, pin 5 is omitted, and the drawing notes that the secondary may be used as primary and the primary as secondary.

It mounts on a PC board with pin-type terminals of min. 0.187" length and is RoHS and REACH compliant, with a shipping weight of 0.02 lbs (0.01 kg).