Lundahl Moving coil input transformer, LL9226

Moving Coil Input Transformer LL9226

LL9226 is an MC transformer based on (and pin compatible with) our classic LL9206, but with reduced copper resistance and level capability. The new design has resulted in an even better frequency response but still with enough no load impedance to maintain the LF bandwidth. The transformer is built up from two coils, each coil with one secondary winding surrounded by two primary windings. Advantages with this structure are excellent frequency response and high immunity to surrounding magnetic fields. All winding ends are available on the pins. Thus, the transformer can be used with a set of different turns ratios.

The LL9226 core is our cobalt based uncut amorphous strip core. The transformer is housed in a mu metal can.

Turns ratio: 1 + 1 + 1 + 1 : 10 + 10
Dims: (Length x Width x Height above PCB (mm)) 30 x 22.5 x 14.5

Spacing between pins: 2.54 mm (0.1")
Spacing between rows of pins: 22.86 mm (0.9")
Weight: 29 g
Rec. PCB hole diameter: 1.5 mm
Static resistance of each primary (average): 5 ?
Static resistance of each secondary (average): 130 ?

Frequency response
(@ -10 dBU, Connection A, source 50? , load 100 k?):

10 Hz -- 50 kHz +/- 1 dB
5 Hz -- 100 kHz +/- 1.5 dB

Distortion
(primaries connected in series, source impedance 40? ): < 0.5% @ -2 dBU, 50 Hz
Primary no load impedance @ 0 dBU, 50 Hz, all in series: 3 k? typically
Core / Can: Amorphous Strip Core / Mu metal can
Isolation between windings / between windings and core: 3 kV / 1.5 kV

Application hint: As the LL9226 does not have Faraday shields, both sides of the transformer should have a common ground reference.