Lundahl LL5402 Audio transformer

Lundahl LL5402 Audio Output Transformer

LL5402 is an audio output transformer for unbalanced drive, ideally used with mixed feedback drive circuits. The effect of capacitance between the primary and the secondary windings is can be reduced if pins 1 and 5 are connected to ground. The windings of the LL5402 are arranged such that cold ends of the primary widings surround each secondary winding.

Turns ratio: 2 + 2 : 1 + 1

Dims (Length x Width x Height above PCB (mm)): 43 x 28 x 21

Pin layout (viewed from component side) and winding schematics:



Spacing between pins: 5.08 mm (0.2")

Spacing between rows of pins: 30.48 mm (1.2")

Weight: 92 g

Rec. PCB hole diameter: 1.5 mm

Static resistance of each primary: 30 W

Static resistance of each secondary: 7 W

Leakage inductance of secondaries (sec. in series): 0.2 mH

No-load impedance: >800 W @ 50 Hz, +20 dBU

Optimum source impedance: Minus 15 W (See application below)

Balance of output (according to IRT, source < 10 W , Load 600 W): > 60 dB

Distortion (connection as application example below, load 600 W) + 22 dBU 0.1% @ 50 Hz

Frequency response (as below , load 600 W): 20 Hz -- 40 kHz +/- 0.3 dB

Voltage loss across transformer (at midband with 600 W load): 0 dB

Isolation between primary and secondary windings / between

windings and core:

4 kV / 2 kV