Lundahl Line input transformer, LL1540

Line Input Transformer LL1540

LL1540 is a high impedance, high level line input transformer. The transformer consists of two coils, each with one primary and one secondary part separated by a electrostatic shield. The core is a high permeability mu-metal core, and the transformer is housed in a mu-metal can. Being a high impedance transformer, the LL1540 should normally be used in a series-series connection.

Turns ratio: 1 + 1 : 1 + 1
Dims (Length x Width x Height above PCB (mm)): 38 x 24 x 17

Spacing between pins: 5.08 mm (0.2")
Spacing between rows of pins: 27.94 mm (1.1")
Offset of earth pin from adjacent row: 2.54 mm (0.1")
Weight: 47 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each primary: 610?
Static resistance of each secondary: 800?

Distortion (source impedance 600?):
+ 20 dBU < 0.1% @ 50 Hz
+30 dBU < 1 % @ 50 Hz

Self resonance point : > 60 kHz
Recommended load for best square-wave response: 22 k? in series with 1nF
Frequency response (source 600?, load 15 k ? ) 5 Hz -- 50 kHz +/- 0.2 dB
Loss across transformer (at 1 kHz with above termination): 0.5 dB
Isolation between windings / between windings and shield: 4 kV / 2 kV