Lundahl Microphone Transformer, LL1528

Microphone Input Transformer LL1528

LL1528 is a microphone input transformers built up from two coils, each with one primary and one secondary section separated by a electrostatic shield. The core is a high permeability mu-metal core, and the transformer is housed in a mu-metal can.

Turns ratio: 1 + 1 : 2.5 + 2.5
Dimensions (Length x Width x Height above PCB (mm)): 38 x 24 x 17

Spacing between rows of pins: 27.94 mm (1.1")
Offset of earth pin from adjacent row: 2.54 mm (0.1")
Weight: 46 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each primary: 42 W
Static resistance of each secondary: 450 W
Distortion (primaries connected in parallel, source impedance 200 W): + 0 dBU primary level, 50 Hz: 0.2 %; + 10 dBU primary level, 50 Hz: 1 %
Self resonance point: > 80 kHz
Optimum termination for best square-wave response (Connection 1:5, source imp. 200W ): 9 kW in series with 3 nF
Frequency response (source and load as above): 10 Hz - 40 kHz +/- 0.3 dB
Isolation between windings/ between windings and shield: 4 kV / 2 kV