Hammond 1140-LN-C 36K to 2.2K Bridging Line Input Transformer, 4:1

The 1140-LN-C is a line input transformer from the 1140 Series with a 4:1 turns ratio and a split secondary. It is designed for line input levels and presents a high input impedance with wide bandwidth and low distortion; the drawing identifies it for balanced bridging input stages. It suits console, preamp and interface designers who need a bridging input that will not load the source.

The impedance ratio is listed as 36K:2.2K / 10K:600. It has the highest rated input level of the 1140 line input transformers at +26 dBu at 20 Hz, with 0.015% THD at 20 Hz and a response of -0.20 dB at 20 Hz and +0.05 dB at 20 kHz. Typical drawing values include 38.5K primary input impedance and 110 secondary output impedance at 1 kHz and +4 dBu, a 4.073:1 turns ratio, 80 dB common mode rejection at 60 Hz and 70 dB at 3 kHz, and THD of 0.001% at 1 kHz and 0.007% at 20 Hz (+4 dBu).

The secondary is split into two 550 sections (green to green/yellow and red to red/yellow) that together give 2200 from green to red/yellow. Primary DCR is 820 and secondary DCR 27/27 at 20 °C. A nickel alloy core and a mu metal can provide the bandwidth and shielding, with 900 pF primary and 725 pF secondary capacitance to shield and case and 500 Vrms dielectric strength.

The 1140-LN-C is a chassis mount part, RoHS and REACH compliant, made in Canada, and ships at 0.2 lbs (0.09 kg).