Tubular Vitreous Enamelled
Wirewound Resistors
1600/1900 Series
Adjustable Resistors
(see Figure 9)
Adjustable resistors use the same basic construction as fixed
resistors already described, and have a window in the vitreous
enamel through which contact is made to the resistive
element by a sliding contact band. The band is fitted with a
clamping screw and nut to retain it firmly in position.
The adjustable winding style has a maximum permissible hot
spot temperature of 300°C and the maximum dissipation, for
an ambient temperature of 20°C, is specified in Table 4. The
Welwyn Components
partial open winding necessitates a reduced maximum
resistance, when compared with fixed resistors, and the
resistance range is also defined in Table 4.
More than one adjusting band can be fitted, up to the
maximum number specified in Table 3.
Adjustable resistors are available in termination styles B, 4B,
AP, C, CB and CP, in sizes 1602 to 1609 inclusive and 1906
and 1908 denoted by prefix ‘V’.
Table 3
Tube
size
1602
1603
1906
1604
1605
1908
1606
1607
1608
1609
20
25
25
30
30
30
27
32
32
38
38
38
3.2
3.7
3.7
3.7
3.7
3.7
3
2
4
2
3
5
20
27
3.2
1
A mm
max.
B mm
max.
Hole C
dia. mm
Max. no of
adjusting
bands
Table 4
Max. dissipation in
20°C ambient (watts)
Type
200°C
hot spot
1602
1906
1603
1604
1605
1908
1607
1606
1608
1609
8
9.5
11
16
21
24
34
41
52
74
300°C
hot spot
15.5
19
22
31
41
47
66
80
101
145
Min. for
styles VC,
VCP
4
4
6
8
6
11
11
14
17
25
Min. for
all other
styles
3
3
6
8
6
10
9
13
16
24
1.6k
2.5k
3.0k
5.3k
4.5k
7.5k
8.1k
13.2k
15.4k
25.5k
Max. for
all styles
Resistance range (ohms)
Manufactured Values
E24 preferred
Standard Selection Tolerance ±10%
All other details of the electrical and environmental
performance of adjustable resistors are the same as for
fixed resistors.
© Welwyn Components Limited
Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
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Issue E · 10.05
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