Hammond 142C 15K:15K Center-Tapped Open Frame PCB Audio Transformer

The 142C is a 142 Series open frame audio transformer for P.C. board mounting with 15K ohm center-tapped primary and secondary windings and a 1:1 turns ratio, the highest impedance pairing in the series. It serves designers working on driver, input, interstage and isolation stages, plus the matching and pulse applications listed on its drawing.

Power level is 100 mW over 200 Hz to 15 kHz, and frequency response is within +/- 1 dB (ref. 1 kHz) at +10 dBm and +20 dBm. Maximum unbalanced primary D.C. current is 4 mA. Total distortion is less than 0.5% for outputs at 200 Hz, decreasing at higher frequencies, and insertion loss is less than 1/2 dB. Either winding may be used as the primary.

The series table lists total winding D.C. resistance of 1020 ohms primary and 1390 ohms secondary (+/- 15%); the part drawing lists 1050 Ω on primary pins 1-3 and 1390 Ω on secondary pins 4-6, both ±20%. Typical inductance is 21.0 H on each winding at 1.0 kHz, 1.0 V, with 102 kΩ impedance per winding and 2.10 H leakage inductance.

Construction is economical and open type, with pin terminals (0.0375" x .02") on pin bobbins set to a standard 0.187" grid pin spacing for P.C. board mounting. The windings are bifilar wound for balanced capacitive and resistance characteristics, and the insulation test is 1500 V rms. Net weight is 0.5 oz. Dielectric strength is 1500 Vrms, operating temperature -40 to 85 °C, storage -40 to 105 °C. The 142C is RoHS and REACH compliant.