Lundahl Interstage transformer, LL1677

High Current Tube Amplifier Interstage Transformer LL1677

LL1677 is a high current interstage transformer with a 1:2 step up ratio. The transformer is wound with a special low capacitance winding technique to achieve best high frequency performance. The transformer has a special high flux, low distortion audio C-core of our own production. For the LL1677, the core air gap is chosen such that the denoted DC current (80mA for a LL1677/80mA) generates a no signal core flux density of 1.2 Tesla when used with all primaries in series. This leaves a flux density swing of 0.4 T for the signal.

Weight: 0.75 Kg
Turns ratio: 1+1+1+1 : 4 + 4
Static resistance, Winding A: 88 ?
Static resistance, winding B: 69 ?
Static resistance, winding C: 800 ?

Max. current through any single primary section: 100 mA
Isolation between primary and secondary windings / between windings and core: 4 kV / 2 kV

Connection: Alt A SE to SE Interst. 1 : 2
Primary DC current for 1.2 Tesla: 80 mA
Primary Inductance: 24 H
Suggested termination for best freq. response: 22k in series with 330 pF
Freq. Response (+/-1dB) @ source impedance (*) Secondary terminated as above: 23Hz - 34 kHz 1 k?
Max output voltage @ 30 Hz: 145 V r.m.s. (410V peak-peak)