Hammond 140REX 600CT to 150 Ohm Shielded Line Transformer, 2:1

The 140REX is a studio grade impedance matching audio transformer with a 600 ohm centre-tapped primary and a 150 ohm secondary, giving a 2:1 turns ratio. The listed typical application is line to line isolation; the drawing also lists input/output isolation, line matching, driver and hybrid applications. It suits studio and AV engineers who need to isolate and step down a 600 ohm line into a 150 ohm load.

The primary is centre tapped on RED - BRN - YEL, with 36.2 ohms DCR per half and 72.4 ohms total; the secondary (GRN - BLU) measures 18.2 ohms DCR. Typical inductance at 1 kHz, 1 V is 3.62 H primary and 0.88 H secondary, with measured impedance of 61.5 kOhm and 15.6 kOhm respectively.

An 80% nickel core provides high permeability with low losses, and the metal can shields the transformer from a broad range of external sources. The 140REX operates from 20 Hz to 20 kHz (+/- 1 dB) at 10.0 dBm output (marked 5 mW), and is designed for lowest distortion at +10 dBm or less. Insertion loss is under 1.0 dB, return loss 22.5 dB, longitudinal balance -65 dB and dielectric strength 500 Vrms.

It is a chassis mount, shielded transformer in a metal can with an adjustable height case bracket. The case is 1.00 in (25 mm) high and 1.25 in (32 mm) in diameter, mounting holes are listed at 1.88 in (48 mm), leads are 5.00 in (127 mm) long, and net weight is 3 oz (shipping weight 0.13 lbs / 0.06 kg). It is made in Canada and RoHS and REACH compliant.