Lundahl High level 600 ? tube amplifier mic/line input transformer, LL7905

Mic/Line Input Transformer LL7905

The LL7905 is a large, high level, high performance audio transformer, made for extraordinary requirements. The transformer combines very high secondary level capability (+37 dBU [54.5V rms] @ 50 Hz) with low copper resistance and is designed for the most demanding applications. The LL7905 consists of two coils, each with two primary and one secondary windings separated by electrostatic shields. The core is a high permeability mu metal lamination core.
The transformer is magnetically shielded by a mu metal case.

Turns ratio: 1 + 1 + 1 + 1 : 5.6 + 5.6
Dims (Length x Width x Height above PCB (mm)): 66 x 32 x 21

Spacing between pins: 5.08 mm (0.2")
Spacing between rows of pins: 5.08 / 45.72 mm (0.2 / 1.8")
Weight: 155 g
Rec. PCB hole diameter: 1.5 mm

Static resistance of each primary (average): 28 W
Static resistance of each secondary (average): 395 W
Distortion (primaries connected in series, source impedance 600 W):
+ 10 dBU primary level, 50 Hz: 0.1 %
+ 28 dBU primary level, 50 Hz: 1 %

Self resonance point: 80 kHz

Optimum termination for best square-wave response
(Connections L4-R2 , source imp. 600 W ): 30k W in series with 100pF

Frequency response
(source and load as above, connection L4-R2, secondary side balanced with or
without grounded center tap): 10 Hz - 55 kHz +/- 1 dB

Frequency response
(source and load as above, connection L4-R2, secondary side unbalanced
with pin 23 grounded): 10 Hz - 30 kHz +/- 1 dB

Isolation between primary and secondary windings/ between windings and shield: 4 kV / 2 kV