Трансформатор LUNDAHL LL7904. Инструкция на английском языке

Tibeliusgatan 7                        International    Domestic
S-761 50 NORRTALJE          Phone    +46 - 176 13930   0176-13930
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LL7904
High Level Splitting Transformer
In many splitting applications, the splitting transformer must have a high immunity to input common mode signals, to
stray magnetic fields from e.g. power transformers and to large ground potential differences in receiving systems.
The LL7904 is developed to handle those types of problems. When designing the LL7904, we have used our well-
established two-coil structure to create a transformer with a high degree of symmetry. The transformer is built up from
two primary windings  (which should be used in parallel) and two secondary windings. Each secondary winding is built
up from two sections, one from each coil and is surrounded by it own electrostatic shields. The symmetric structure
results in an internal cancellation of noise signals caused by external magnetic field (humbucking). It also increases
immunity to ground noise between secondary systems and reduces the effects of input common mode signals.
The transformer is housed in a mu-metal can and is impregnated in solventless epoxy resin.
Turns ratio:                                             1 + 1 : 1 + 1
Pin layout (viewed from pins side) and simplified winding schematics:
18 (+ core)
Note! Pin’s side view
8                   14
1     7                    13     19
2     8                    14     20
7                   22
15     21
11                    16
16     22
5     11                   17     23
12                    13
6     12                   18     24
17
Housing      15 (use with 17)
Spacing between            Spacing between                      Recommended
pins                   rows of pins                     PCB hole diameter:
5.08 mm  (0.2")       5.08 / 45.72 mm  (0.2 / 1.8")               1.7 mm
Dimensions (Max. L x W x H above PCB(mm))                        66 x 32 x 21
Weight:                                                          155 g
Static resistance of each primary:                               55 W
Static resistance of each secondary  (Pins 14 - 22 and pins 16 - 13 resp.):  43 W and 66 W
Distortion                                                       0.1% @ +16 dBU,  50 Hz
< 1 %  @ +23 dBU, 50 Hz
Frequency response (Ref : 0 dBu, 1kHz)                           10 Hz -- 80 kHz +/- 0.5 dB
Test arrangement: Parallel input - parallel output . Source 150W  , load 10 kW
CMRR  at 20 kHz  (Source 600 ohms, load 2 x 10k)                 > 60 dB
CMRR at 20 kHz from sec. to sec.  (Source 600 ohms, load 2 x 10k)  > 40 dB
Isolation test  primary - secondary  / secondary - secondary / 18 - (15+17)  4 kV / 2 kV / 1 kV  RMS
Application example.
Splitting 1: 1 + 1
Primary signal from
microphone cable, with or
without phantom power.               8                  +
7
LL7904          +
12
11
+                15    17
Secondaries can be connected individually.
(Function does not require that both
secondaries are connected/used)
R001110
LL7904
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LL7904 application example.
1 + 2 Out Splitting box                        Front house
desk.
With phantom
On stage mic.
power supply
1
2
3
Before connecting  splitting box
With splitting box
Front house desk.
With phantom
power supply
On stage mic.
1
2
3
Direct output
3   2   1     1   2   3
+
Splitting box
7     8        11    12
LL7904
22  14  18   15 + 17  16  13
SW1
SW2
+               +
3   2   1      1   2   3
Monitor                                                                              Recording
Desk      3                                                                        3  Truck
2                                                                        2
1                                                                        1
Ideally, SW1 and SW2 should be open.
Close SW1 and / or SW2 when E1 and / or E2 do not receive ground
reference from Monitor desk or from Recording truck respectively.
LL7904
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