Lundahl Line input transformer, LL1531

High Impedance Line Input Transformer LL1531

LL1531 is a small size, high impedance line input transformer for bridging input applications The transformer consists of two coils, each with one primary and one secondary winding separated by an electrostatic shield. The two secondary windings are internally connected in series. The core is a high permeability mu-metal lamination core. The transformer is magnetically shielded by a mu-metal housing.

Being a high impedance transformer, the LL1531 should normally be used with primaries connected in series.

Turns ratio: 1 + 1 : 2
Dims (Length x Width x Height above PCB (mm)): 28 x 17 x 15

Spacing between pins: 3.81 mm (0.15")
Spacing between rows of pins: 20.32 mm (0.8")

Weight: 25 g
Rec. PCB hole diameter: 1.5 mm

Static resistance of each primary: 500W
Static resistance of secondary: 1.3kW

Distortion (primaries connected in series, source impedance 600W ):
+ 10 dBU primary level, 50 Hz: 0.2 %
+ 20 dBU primary level, 50 Hz: 1 %

Self resonance point: > 80 kHz
Optimum termination for best square-wave response (source imp. 600W ): 8 kW in series with 1.2 nF
Frequency response (source and load as above): 10 Hz - 25 kHz +/- 0.3 dB
Isolation between windings/ between windings and shield: 3 kV / 1.5 kV