
Mains Transformers for Tube Amplifiers
LL1648, LL1649, LL1650, LL1651
C-core mains transformers. The core is assembled with a small air-gap to compensate for any mains DC-
unbalance. Estimated power rating 250 VA which can be increased with good cooling. Magnetic stray is
extremely small if secondaries of the two coils are loaded identically.
Physical dimensions, pin and mounting hole layout (all dimensions in mm)
Winding schematics:
Connection alternatives. Primary in series for 230V (left) and in parallel for 115V (right).
Copper resistance, no load output voltages and max recommended transformer current (rms) with
primary connected to 230 V serial / 115V parallel and Sec 1 connected as above
Type Primary res.
Serial/parallel
Sec 1
Sec 2
Sec 3
Sec 4
Sec 5
LL1648
7.5 Ω / 1.9 Ω 20 Ω / 350 V
0.63A
0.1 Ω / 5.9 V
3.1A
0.1 Ω / 5.9 V
3.1A
0.1 Ω / 6.6 V
3.1A
0.1 Ω / 6.6 V
3.1A
LL1649
7.5 Ω / 1.9 Ω 8.4 Ω / 230 V
1.0A
0.1 Ω / 6.6V
3.1A
0.1 Ω / 6.6V
3.1A
0.1 Ω / 6.6 V
3.1A
0.1 Ω / 6.6 V
3.1A
LL1650
7.5 Ω / 1.9 Ω 20 Ω / 350 V
0.63A
0.1 Ω / 6.6 V
3.1A
0.1 Ω / 6.6V
3.1A
0.1 Ω / 6.6 V
3.1A
0.1 Ω / 6.6 V
3.1A
LL1651
7.5 Ω / 1.9 Ω 42 Ω / 500V
0.43A
0.1 Ω / 6.6 V
3.1A
0.1 Ω / 6.6V
3.1A
0.1 Ω / 6.6 V
3.1A
0.1 Ω / 6.6 V
3.1A
Please note! Output current from rectifier: 63% of above with condensor input rectifier, 95% of above with
choke input rectifier.
Secondary connections
Bottom view
Primary connections
1
5
6
2 3
7
8
4
16a
18
17
15a
12
14a
13a
11
4 x M4
Mounting holes
110
53
90
78
85
8 7
1 2 4
3
5 6
13 11 14 12 17 15 18 16
Coil 1 Coil 2
Tibeliusgatan 7 International Domestic
S-761 50 NORRTÄLJE Phone +46 - 176 13930 0176-13930
SWEDEN Fax +46 - 176 13935 0176-13935
Weight 2.5 kg
8
7
6
5
4
3
2
1
18
16
17
15
14
12
13
11
Sec 5
ec 4
Sec 3
ec 2
Prim
230V
Sec 1
8
7
6
5
4
3
2
1
18
16
17
15
14
12
13
11
Sec 5
Sec 4
Sec 3
Sec 2
Prim
Sec 1
R010507
14
13
16
15
14a, 13a, 16a and 15a are old positions
for secondary pins 14, 13, 16 and 15