Hammond 140PEX 150/600 to 600/2400 Ohm Shielded Line Transformer

The 140PEX is a studio grade impedance matching audio transformer with split windings: a 150/600 ohm primary and a 600/2400 ohm secondary. The listed typical application is line to base, and the drawing adds input/output isolation, line matching, driver and hybrid applications. It gives studio technicians and equipment designers flexible matching from one part.

With dual primary and dual secondary windings, the drawing lists available turns ratios of 1:1, 1:2 and 1:4; the series table gives the overall ratio as 1:2. The primary sections are RED - YEL and ORG - BRN (29.0 ohms DCR each, 58.0 ohms total) and the secondary sections are GRN - BLU and VIO - BLK (95.0 ohms each, 190.0 ohms total).

An 80% nickel core provides high permeability with low losses, and the drawing notes a mumetal can for shielding from a broad range of external sources. The unit operates across 20 Hz to 20 kHz (1 dB) and is rated for 10.0 dBm output (marked 5 mW). Typical inductance at 1 kHz, 1 V is 14.5 H primary and 55.0 H secondary; insertion loss is under 0.8 dB, return loss 30 dB, longitudinal balance -70 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). The 140PEX is made in Canada and RoHS and REACH compliant.