Ultra Precision
Metal Film Resistors
Welwyn Components
MAR 40/42 series
• Tolerance down to 0.005%
Very low TCRs
•
Rugged moulded protection
•
Matched sets available
•
Electrical Data
Notes
Power rating at 85°C
Resistance range
watts
ohms
volts
0.3
20R0 to 400K
Higher values by agreement
Limiting element voltage
TCR (0°C to +60°C)
TCR (-55°C to +125°C)
Resistance tolerance
Standard values
250
2 (T18) & 5 (T16)
ppm/°C
ppm/°C
%
5 (T18) & 10 (T16)
0.005, 0.01, 0.02, 0.05, 0.1, 0.25, 0.5 & 1
E24, E96 preferred
80
Any value to order
Thermal impedance
Ambient temperature range
°C/watt
°C
- 55 to +155
Physical Data
Dimensions (mm) and Weight (g)
L
W
Wt.
H
Type
L max.
7.75
H max. W max.
T min.
d nom.
0.6
S nom.
3.8
nom.
0.65
0.65
d
T
MAR 40
MAR 42
8.64
8.64
3.3
3.3
25.4
25.4
8.25
0.6
5.1
S
Marking
Construction
Type reference, TCR code, resistance value and tolerance. The
Ceramic rods are coated with a metal film and plated steel
resistance value marking conforms to IEC 62.
caps are force fitted. A helical cut is used to adjust the film to
its final value. Termination wires are welded to the caps and
the resistor is protected with a multiple lacquer coat and
encapsulated in an epoxy moulded protection.
Solvent Resistance
The body protection and marking are resistant to all normal
industrial cleaning fluids suitable for printed circuits.
Terminations
Material
Solder-coated copper wire.
Strength
The terminations meet requirements of
IEC 68.2.21 and MIL-STD 1276.
Solderability
The terminations meet the requirements of
IEC 115-1, Clause 4.17.3.2 and MIL-STD 202.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
© 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
Issue B · 03.02
180