Lundahl Line input transformer for ZF input circuitsr, LL7101

Zero Field Input Transformer LL7101

In a Zero Field (ZF) transformer application, the magnetic field caused by the input signal is balanced by a feedback loop which includes the transformer's secondary winding. (See application example below). The feedback arrangement extends the low frequency range to almost DC in spite of the small size of the transformer.

Turns ratio: 1 + 1 : 1.38
Dims: (Length x Width x Height above PCB (mm)) 28 x 18 x 11

Housing: Mu-metal
Core: Mu-metal
Impregnation: Solventless epoxi resin
Spacing between pins: 3.81 mm (0.15")
Spacing between rows of pins: 20.32 mm (0.8")
Rec. PCB hole diameter: 1.5 mm
Weight: 16 g
Static resistance of each primary: 138 W
Static resistance of secondary: 28 W
Isolation between windings: 2 kV
Recommended primary resistance: 10 kW -- 20 kW