Hammond 109G 600:250 Ohm Center-Tapped 2W Potted Audio Transformer

The 109G is a miniature epoxy potted audio transformer from the 2 W-rated 109 Series, built for printed circuit board mounting. It matches a 600 ohm center-tapped primary to a 250 ohm center-tapped secondary with a 1.55:1 turns ratio, for line matching into a 250 ohm circuit. 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 600 ohm CT on the primary (pins 1-3) and 250 ohm CT on the secondary (pins 4-6). The ordering table lists D.C. resistance of 43 ohms primary and 24 ohms secondary (+/- 20%) and a maximum D.C. unbalance of 6 mA. The part drawing gives typical values of 40 Ω (20Ω/20Ω) primary DCR, 0.70 H primary and 295.0 mH secondary inductance, 3.26 mH leakage inductance, a 1.55:1 turns ratio and 100 Vrms dielectric strength.

The series is rated 2 watt (+/- 1.5 db, 300Hz. - 50 KHz.), and the 109G 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).