Lundahl Amorphous Core Interstage / line output transformer, LL1660AM-10mA

Amorphous Core Tube Amplifier Interstage Transformer / Line Output Transformer LL1660-10mA

LL1660 is an interstage / line output transformer for tube amplifiers. The transformer is available with different core air gap for PP or SE drives.
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. The LL1660PP is assembled with a small core air gap to allow for some DC current unbalance.
For the S.E. versions of the LL1660, the core air gap is chosen such that the denoted DC current (18mA for a LL1660/18mA) generates a no signal core flux density of 0.9 Tesla when used with all primaries in series. This leaves a flux density swing of 0.7 T for the signal.

Weight: 0.75 Kg
Turns ratio: 1+1+1+1 : 2.25+2.25
Static resistance, winding A: 315 W
Static resistance, winding B: 240 W
Static resistance, winding C: 625 W
Max. current through any single section: 50 mA
Isolation between primary and secondary windings / between windings and core: 4 kV / 2 kV

Connection: Alt S SE to SE Interst. 4 : 4.5
Primary DC current for 0.9 Tesla: 10 mA
Primary Inductance: 130H
Freq. Response (+/-1dB) @ source impedance (*) Secondaries open: 25Hz - 40 kHz 14 kW
Max output voltage @ 30 Hz: 250 V r.m.s.

(*) The source impedances used in the tables indicates a recommended upper limit, unless freq. response can be compromised. At lower source impedance resonance peaking will occure. It can be reduced using secondary load resistors.