Ohmite F20J40R Wirewound Chassis Mount Resistor - Equivalent & Substitute Parts

Part Overview

The Ohmite F20J40R is a 40 Ohms ±5% 20W wirewound chassis mount resistor from the Stackohm® 250 series. This component is designed for high-power applications requiring stable resistance performance across extended temperature ranges. The part is currently active in production with 990 units in stock. Substitute parts become necessary when design requirements shift toward lower power dissipation, when specific compliance certifications are required, or when alternative packaging configurations are needed for system integration.

Substiute Parts

F20J40R

OhmiteIn Stock: 1047F20J40R Datasheet

Current PartRFQ

F10J40R

OhmiteIn Stock: 971F10J40R Datasheet

Parametric EquivalentRFQ

F10J40RE

OhmiteIn Stock: 862F10J40RE Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the F20J40R are identified based on strict electrical and mechanical parameter matching within the Stackohm® 250 series. The primary substitution criterion is maintenance of identical resistance value (40 Ohms) and tolerance (±5%), combined with compatible physical dimensions, mounting configuration, and thermal characteristics.

The F10J40R and F10J40RE are parametric equivalents that maintain all critical electrical specifications except power rating, which is reduced from 20W to 10W. This reduction in power dissipation capacity represents the primary functional difference. Both substitute parts retain the same resistance value, tolerance, temperature coefficient, operating temperature range, coating type, mounting features, physical dimensions, and lead style as the main part.

Key parameters determining substitution eligibility:

• Resistance value: 40 Ohms (identical across all parts)
• Tolerance: ±5% (identical across all parts)
• Temperature coefficient: ±260ppm/°C (identical across all parts)
• Operating temperature range: -55°C to 350°C (identical across all parts)
• Composition: Wirewound (identical across all parts)
• Mounting configuration: Flange Braces, Right Angle (identical across all parts)
• Physical dimensions: 0.750" L x 0.375" W, 0.375" height seated (identical across all parts)
• Lead style: Solder Lugs (identical across all parts)
• Package type: Radial, Flat Oval (identical across all parts)

Parameter Comparison

Engineering Selection Recommendations

Selection between the F20J40R and its substitutes depends on application power dissipation requirements and regulatory compliance needs.

The F20J40R remains the appropriate choice for applications requiring 20W power dissipation capacity. This part is active in production with robust inventory availability.

The F10J40R is suitable for applications with maximum power dissipation of 10W or less. This part maintains identical electrical and mechanical specifications to the F20J40R except for reduced power rating. It is active in production with 861 units in stock.

The F10J40RE is suitable for applications with maximum power dissipation of 10W or less where ROHS3 compliance is required. This part is the only substitute offering RoHS3 certification while maintaining all other electrical and mechanical specifications. It is active in production with 764 units in stock.

All three parts are manufactured by Ohmite and belong to the Stackohm® 250 series. Selection should be based on actual circuit power dissipation requirements and applicable regulatory compliance standards for the end application.

Frequently Asked Questions (FAQ)

Q: Can F10J40R or F10J40RE be used as direct replacements for F20J40R?

A: F10J40R and F10J40RE are parametric equivalents with identical electrical and mechanical specifications except for power rating. They can be used as direct replacements only if the application circuit dissipates 10W or less. If the circuit requires 20W dissipation capacity, these substitutes are not suitable.

Q: What is the primary difference between F10J40R and F10J40RE?

A: Both parts have identical electrical and mechanical specifications. The primary difference is regulatory compliance: F10J40RE is ROHS3 compliant, while F10J40R is RoHS non-compliant. Select F10J40RE for applications requiring RoHS3 certification.

Q: Are the physical dimensions identical across all three parts?

A: Yes. All three parts share identical dimensions: 0.750" L x 0.375" W (19.05mm x 9.53mm) with maximum seated height of 0.375" (9.53mm). They use identical mounting features (Flange Braces, Right Angle) and lead style (Solder Lugs).

Q: Do all parts operate across the same temperature range?

A: Yes. All three parts operate from -55°C to 350°C with identical temperature coefficient of ±260ppm/°C.

Q: What packaging options are available?

A: F20J40R is supplied in standard packaging. F10J40R and F10J40RE are supplied in bulk packaging. All parts use identical Radial, Flat Oval package/case configuration.

Q: Are all parts from the same manufacturer?

A: Yes. All three parts are manufactured by Ohmite and belong to the Stackohm® 250 series.