
Mains Transformers for Tube Amplifiers
LL1683
C-core mains transformer. The core is assembled with a small air-gap to compensate for any mains DC-unbalance. Estimated
power rating 120 VA, which can be increased with good cooling. The 2 x 250V secondaries are internally divided between
the two coils. As a result, the transformer can be used with bridge or full wave rectifiers without a problem of asymmetric
load. Magnetic stray is extremely small if filament secondaries of the two coils are loaded identically.
Physical dimensions, pin and mounting hole layout (all dimensions in mm)
Winding schematics:
Usage hints
No load output voltage, max recommended transformer current (rms) and coil resistance with primary
connected to 230 V series / 115V parallel
Primary res.
Series/parallel
Sec 1
Pins 15 - 22
Sec 2
Pins 24 - 17
Sec 3
Pins 26 - 19
Sec 4
Pins B7 – B4
Sec 5
Pins B6 – B1
Sec 6
Pins B3 – B8
Sec 6
Pins B2 – B5
7.5 Ω / 1.9 Ω
250V / 80mA
100Ω
250V / 80mA
100Ω
48V / 0.1A
40Ω
6.6 V / 3A
0.2 Ω
6.6 V / 3A
0.2 Ω
5.2 V / 3A
0.2Ω
5.2 V/ 3A
0.2Ω
Please note! Output current from rectifier: 63% of above with cap. input rectifier, 95% of above with choke input rectifier.
B7
B4
Filament current connections
Bottom view
High voltage connections
12
4 x M4
Mounting holes
98
35
75
24
17
2
4
12
10
B3
B8
B2
B5
15
22
B6
B1
Coil 1
Coil 2
TRANSFORMERS
Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
Weight 1.4 kg
R030423
B5
B4
26
19
15
4
2
10
17
19
22
24
26
B1
B2
B3
B6
B7
B8
115V
115V
6.6V
5.2V
250V
48V
250V
5.2V
6.6V
Split between coils
2
Prim
4
10
12
2
Prim
4
10
12
Bridge
rectifier
15
24
22
17
Full wave
(tube) rectifier
15
22
24
17
NOTE: When used with common mode
blocking choke input supply, 22+24 is
not grounded here.