Hammond 109L 10K CT to 3.2 Ohm 2W Potted PCB Output Transformer

The 109L is a miniature epoxy potted audio transformer from the 2 W-rated 109 Series, built for printed circuit board mounting. It steps a 10K ohm center-tapped primary all the way down to a 3.2 ohm secondary with a 55.3:1 turns ratio, an output transformer for driving a 3.2 ohm load from a high-impedance stage. Designers of audio input, line matching, isolation and output stages will find it a compact, board-level way to add transformer coupling.

Nominal impedances are 10K ohm CT on the primary (pins 1-3) and 3.2 ohm on the secondary (pins 4-6). The ordering table lists D.C. resistance of 700 ohms primary and 0.37 ohms secondary (+/- 20%) and a maximum D.C. unbalance of 1.5 mA. The part drawing gives typical values of 300.0 Ω (150.0Ω/150.0Ω) primary DCR, 5.81 H primary and 2.146 mH secondary inductance, 23.00 mH leakage inductance, a 55.3:1 turns ratio and 100 Vrms dielectric strength.

The series is rated 2 watt (+/- 1.5 db, 300Hz. - 50 KHz.), and the 109L drawing lists a power level of 2.0W from 300 Hz to 50 kHz with typical output power of 2 W. Frequency range is 300 Hz to 50 kHz +/- 1.5 dB at +0 dBm and 300 Hz to 50 kHz +/- 1.5 dB at +27 dBm, measured with no D.C. saturation. Power ratings are maximum at the lowest frequency, and the secondary may be used as the primary and vice versa.

Construction is rugged epoxy potting in a black molded case, producing a completely sealed unit, with pin type P.C. board terminals of at least 0.187" length. The part withstands soldering for 10 seconds at 260 °C, is rated for 85 °C maximum ambient, and the casting epoxy has a workable range of -40 °C to +105 °C. It is RoHS and REACH compliant, made in Canada, and ships at 0.1 lbs (0.05 kg).