Hammond 1140-LU-F 600 to 150 Ohm Quad-Filar Line Output Transformer

The 1140-LU-F is a 600:150 line output transformer from the 1140 Series with quad-filar windings on an 80% Ni core. The four 150 Ω windings (two primary, two secondary) can be connected in different ways, and the drawing states the part is best suited for 1:2 step up applications; where a 1:1 ratio is needed, the 1140-LU-G gives better performance. It is aimed at studio and broadcast designers building line output and step-up stages.

The series table rates it at a 600:150 impedance ratio and 2:1 turns ratio, +27 dBu maximum input at 20 Hz, 0.001% THD at 20 Hz and a frequency response of -0.01 dB at 20 Hz and +0.01 dB at 20 kHz. The drawing, measured with 600 Ω input and output impedance and a 1:1 connection, lists +27 dBu into 600 Ω at 20 Hz, THD of 0.007% at 1 kHz and 0.001% at 20 Hz (4 dBu), and a response of -0.001 dB at 20 Hz and +0.007 dB at 20 kHz.

Other typical values are 180Ω primary input impedance and 80Ω secondary output impedance at 1 kHz and 0 dBu, 30/30 Ω DCR on each side at 20 °C, 105 dB common mode rejection at 60 Hz and 75 dB at 3 kHz, 30 nF primary and 80 pF secondary capacitance to shield and case, and 250 Vrms dielectric strength. The drive signal should have no DC component and the source impedance should be as low as possible.

The 1140-LU-F is open style (not Mu Metal) for chassis mounting, with colour-coded leads of 8" minimum length: brown/orange and black/white primaries, green to green/yellow and red to red/yellow secondaries. It is RoHS and REACH compliant, made in Canada, and ships at 0.2 lbs (0.09 kg).