Lundahl Amorphous Core Interstage transformer, LL2746AM

Stepup 1:2 Amorphous Core tube amplifier interstage transformer LL2746AM (D)

The LL2746 is a three-section dual coil C-core tube amplifier stepup interstage transformer. The coil is wound using our low capacitance, high internal isolation technique with internal multilayer isolation foil where layer-to-layer signal voltage is big. Winding order is chosen to minimize destructive capacitive energy buildup between primary and secondary sections. The core is an audio C-core of our own production.

Turns ratio 1+1 : 2+2

Weight: 1.35 kg
Static resistance of each primary: 75 ?
Static resistance of secondary: 290 ?
Isolation between windings / between windings and core: 4 kV / 2 kV
Max recommended DC current through any primary winding: 220mA (5W heat dissipation)

Primary inductance (approx): 45H
Max primary signal , at 30 Hz (Operating point 1.2T): 80V r.m.s. (220V peak-peak)

Frequency response, connected as below (source 3.9k, load 50pF) but with V+ connected to ground: -3dB at 15Hz; -3dB at 25kHz, +/- 1dB 22Hz 18kHz