150CT Impedance Primary Ohms 12 Impedance Secondary Ohms 3.54:1 Audio Transformer 300Hz to 100kHz Through Hole
Features
Power Level: 50 mW
Matching Impedance (Primary): 150 Ohm Center Tap
Matching Impedance (Secondary): 12 Ohm
Overall Turns Ratio: 3.54:1.0
DC Resistance (Primary): 18.0 Ohm
DC Resistance (Secondary): 2.7 Ohm
Max. Primary Unbalanced DC Current: 10.0 mA
Frequency Response Range: ±2.0 DB, at 300 Hz to 100K Hz
Pri-Sec Hipot Test Voltage: 1,000 VRMS for 1 Second
Working DC Voltage: 150 V
Operating Temperature Range: -40 to 85 °C
Storage Temperature Range: -40 to 85 °C
Non-Condensing Relative Storage Humidity: 10 to 95 %
Transformer Contact Type: Center Tap
Mil Type Number: TF5S21ZZ
Industry Standard: MIL-T-27E
Case footprint dimensions: 0.310 by 0.410 inch
Pin diameter: 0.020 inch
Lead material: Gold Plated, high strength Nickel alloy
Case material: Epoxy Molded, UL94 V-0 rated
RoHS Compliance: Meets 2015/863/EU (RoHS 3) as of February 2016
Overview
The Triad SP-42 is a miniature audio impedance matching transformer designed and rated to MIL-T-27E (Red Spec) requirements, with Mil Type Number TF5S21ZZ. It provides impedance transformation from a 150 Ω center-tapped primary to a 12 Ω secondary, with an overall turns ratio of 3.54:1 and a rated power level of 50 mW. The frequency response spans ±2.0 dB from 300 Hz to 100 kHz, making this transformer suitable for military-aerospace, medical, and professional audio applications where high reliability and traceable compliance are required.
The center-tapped primary supports balanced signal connections, making the SP-42 well suited for interfacing balanced audio lines or low-level signal sources to lower-impedance loads such as amplifier inputs or downstream signal-processing stages. The 10.0 mA maximum primary unbalanced DC current rating, combined with a working DC voltage of 150 V and a hipot test rating of 1,000 VRMS, provide a safety margin appropriate for demanding or regulated environments. Mil-spec qualification and an operating temperature range of -40 to 85 °C support use where environmental robustness is a design requirement.
The SP-42 uses plug-in terminals precision spaced to provide fixed mounting centers, housed in a compact case footprint of 0.310 x 0.410 inch. The UL94 V-0 rated epoxy molded case includes a 0.020 inch recess for ease of solder inspection, and leads are gold plated, high strength Nickel alloy, 0.020 inch in diameter. Designers should confirm that the primary DC resistance of 18.0 Ω, secondary DC resistance of 2.7 Ω, and the 300 Hz low-frequency cutoff are compatible with their circuit requirements, and verify that the 2015/863/EU (RoHS 3) compliance status meets their project needs.
