F40J400 Equivalent & Substitute Parts

Part Overview

The F40J400 is a 400 Ohms ±5% 40W wirewound chassis mount resistor manufactured by Ohmite, part of 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 818 units in stock. Substitute parts are identified when equivalent electrical specifications and mechanical compatibility allow direct replacement in circuit designs.

Substiute Parts

F40J400

OhmiteIn Stock: 914F40J400 Datasheet

Current PartRFQ

F30J400E

OhmiteIn Stock: 775F30J400E Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the F40J400 is determined by the following critical parameters:

• Resistance Value: Must be 400 Ohms
• Tolerance: Must be ±5%
• Composition: Must be Wirewound
• Temperature Coefficient: Must be ±260ppm/°C
• Operating Temperature Range: Must support -55°C to 350°C
• Coating/Housing Type: Must be Vitreous Enamel Coated
• Mounting Feature: Must be Flange Braces, Right Angle
• Lead Style: Must be Solder Lugs
• Package/Case: Must be Radial, Flat Oval
• Series: Must be Stackohm® 250

The F30J400E meets all these criteria and is classified as a parametric equivalent. The primary difference is the power rating (30W versus 40W), which represents a reduced power handling capability. This substitution is valid only when circuit power dissipation requirements do not exceed 30W.

Parameter Comparison

Engineering Selection Recommendations

The F30J400E is a valid substitute for the F40J400 when circuit design specifications permit operation at 30W power dissipation. Both parts maintain identical electrical characteristics including resistance, tolerance, temperature coefficient, and operating temperature range. Both are active production components from the same manufacturer and series.

The F30J400E offers improved regulatory compliance, meeting ROHS3 standards compared to the non-compliant status of the F40J400. This compliance advantage may be significant for applications subject to environmental regulations.

Selection between these parts depends solely on power dissipation requirements. If the circuit dissipates 30W or less, the F30J400E is suitable. If circuit power dissipation exceeds 30W, the F40J400 is required to maintain safe operating margins.

Frequently Asked Questions (FAQ)

Q: Can the F30J400E replace the F40J400 in all applications?

A: The F30J400E is suitable only when circuit power dissipation does not exceed 30W. The 40W rating of the F40J400 is necessary for applications requiring higher power handling capability.

Q: Are the physical dimensions compatible between these parts?

A: Both parts use identical mounting features (Flange Braces, Right Angle), lead style (Solder Lugs), and package type (Radial, Flat Oval). The F30J400E has a smaller length dimension (1.250" versus 2.000"), but both maintain the same width (1.000") and seated height (0.563"). Verify mechanical fit in your specific application layout.

Q: What is the difference in RoHS compliance between these parts?

A: The F40J400 is RoHS non-compliant, while the F30J400E is ROHS3 compliant. If your application or market requires RoHS compliance, the F30J400E is the appropriate selection, provided power requirements do not exceed 30W.

Q: Do these parts have identical electrical performance?

A: Yes. Both parts share identical resistance (400 Ohms), tolerance (±5%), temperature coefficient (±260ppm/°C), and operating temperature range (-55°C to 350°C). The only electrical difference is power rating.

Q: What packaging options are available?

A: The F40J400 is supplied in standard packaging, while the F30J400E is supplied in bulk packaging. Confirm packaging requirements for your procurement process.