Hammond 1140-LU-B 600 Ohm 1:1 Line Output Transformer, 49% Nickel

The 1140-LU-B is a 1:1, 600:600 line output transformer from the 1140 Series, intended for driving balanced 600 Ω lines from studio and broadcast equipment. It is designed with bi-filar windings and a 49% Ni core, which the manufacturer states gives low distortion levels and good output levels.

It can drive 600 Ω loads up to +21 dBu at 20 Hz. Rated THD at 20 Hz is 0.150% and the frequency response is -0.20 dB at 20 Hz and +0.03 dB at 20 kHz. On the drawing, typical THD is 0.002% at 1 kHz and 0.15% at 20 Hz (4 dBu), common mode rejection is 105 dB at 60 Hz and 70 dB at 3 kHz, and phase shift is 0.5° at 20 Hz and -1.0° at 20 kHz.

Primary and secondary DCR are each 58 Ω at 20 °C. Typical primary input impedance is 710KΩ and secondary output impedance 115Ω at 1 kHz and 0 dBu. Capacitance is 20 nF primary and 45 pF secondary to shield and case, and dielectric strength is 250 Vrms. Because of the Ni core, the drive signal should have no DC component and the source impedance should be as low as possible.

The 1140-LU-B is an open style chassis mount transformer (the series notes line output types are not Mu Metal). Leads are colour coded and at least 8" long: brown/orange primary and green to green/yellow secondary. It is RoHS and REACH compliant, made in Canada, and ships at 0.2 lbs (0.09 kg).