Lundahl Microphone Transformer, LL1571

Microphone Input Transformer LL1571

LL1571 is a microphone input transformer built up from two coils and a high permeability mu metal core. Each coil is wound in three sections with electrostatic shields connected to separate pins. This result in a transformer with a very broad band, also ideal for splitting purpose. The two-coil structure in combination with the mu-metal can results in a high immunity to external magnetic fields.

Turns ratio: 1 + 1 : 1.75 + 1.75
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 rows from adjacent rows: 2.54 mm (0.1")
Weight: 48 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each primary: 50 ?
Static resistance of each secondary: 175 ?
Distortion (primaries in series, source impedance 800? ): + 6 dBU 0.1% @ 50 Hz; +16 dBU < 1 % @ 50 Hz
Self-resonance point: > 200 kHz
Optimum load for best square-wave response (Source imp. 800 ?, primaries and secondaries in series): 4 k? in series with 0.3 nF
Frequency response (source and load as above ): 10 Hz -- 100 kHz +/- 0.5 dB
Isolation between windings / between windings and shields: 4 kV / 2 kV