Lundahl Line input transformer, LL1544A

Audio Transformer LL1544A

LL1544A is a line input / general purpose audio transformer which can be used in many different applications ranging from bridging input to microphone input applications. The transformer is built up from two threesection coils with interleaved Faraday shields. The core is a two-component amorphous strip core. This core type combines a high sensitivity for very low signal levels with excellent high-level capabilities. In addition, as this type of core does not store energy (unlike conventional mu-metal cores), at low frequencies phase response is excellent and resonance with a series capacitor is practically eliminated.

The LL1544A replaces previous types LL1544 and LL1554.

Turns ratio: 1 + 1 + 1 + 1 : 2 + 2
Dims: (Length x Width x Height above PCB (mm)) 30 x 22.5 x 14.5

Spacing between pins: 2.54 mm (0.1")
Spacing between rows of pins: 22.86 mm (0.9")
Weight: 27 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each primary (average): 130 W
Static resistance of each secondary (average): 260 W
Self resonance point: > 220 kHz
Recommended load for best square-wave response (Termination alternative A below): 6.7 kW + 470 pF
Frequency response (source 600W, load (6.7 kW + 470 pF) in parallel with 56 kW): 10 Hz - 70 kHz +/- 0.5 dB @ 0 dBU
Loss across transformer (at 1kHz with termination as above): 0.2 dB
Isolation between windings / between windings and shields: 3 kV / 1.5 kV