F55J75R Equivalent & Substitute Parts

Part Overview

The F55J75R is a 75 Ohms ±5% 55W 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 784 units in stock. Substitute parts are identified when equivalent electrical specifications and mechanical compatibility allow direct replacement in circuit designs.

Substiute Parts

F55J75R

OhmiteIn Stock: 874F55J75R Datasheet

Current PartRFQ

F40J75RE

OhmiteIn Stock: 708F40J75RE Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

The F40J75RE qualifies as a parametric equivalent based on the following criteria:

Matching Electrical Specifications:

• Resistance value: 75 Ohms (identical)
• Tolerance: ±5% (identical)
• Temperature coefficient: ±260ppm/°C (identical)
• Operating temperature range: -55°C to 350°C (identical)
• Composition: Wirewound (identical)

Matching Mechanical Specifications:

• Coating/housing type: Vitreous Enamel Coated (identical)
• Mounting feature: Flange Braces, Right Angle (identical)
• Lead style: Solder Lugs (identical)
• Package/case: Radial, Flat Oval (identical)
• Height seated (max): 0.563" (14.29mm) (identical)

Differing Specification:

• Power rating: F40J75RE is rated at 40W versus F55J75R at 55W

The F40J75RE operates within the same electrical and mechanical envelope as the F55J75R. The reduced power rating represents the primary distinction between these components.

Parameter Comparison

Engineering Selection Recommendations

F55J75R Selection Criteria:

• Applications requiring 55W continuous power dissipation at 75 Ohms
• Designs where maximum power handling is specified
• RoHS non-compliant applications or legacy system requirements

F40J75RE Selection Criteria:

• Applications with power dissipation requirements at or below 40W at 75 Ohms
• New designs requiring ROHS3 compliance
• Space-constrained layouts where the reduced physical length (2.000" vs 4.600") provides advantage
• Systems where regulatory compliance with RoHS3 is mandatory

Both components share identical electrical performance characteristics, temperature stability, and mechanical mounting interfaces. Selection between these parts depends on power rating requirements and compliance status.

Frequently Asked Questions (FAQ)

Q: Can F40J75RE replace F55J75R in all applications? A: F40J75RE can replace F55J75R only in applications where the actual power dissipation does not exceed 40W. The electrical characteristics, temperature coefficient, and mounting interfaces are identical. Power rating is the limiting factor for substitution.

Q: What is the physical size difference between these parts? A: The F55J75R measures 4.600" L x 1.000" W (88.90mm x 25.40mm), while the F40J75RE measures 2.000" L x 1.000" W (50.80mm x 25.40mm). Both maintain the same height of 0.563" (14.29mm) when seated. The reduced length of the F40J75RE reflects its lower power rating.

Q: Are there compliance differences between these parts? A: Yes. The F55J75R is RoHS non-compliant, while the F40J75RE is ROHS3 compliant. This distinction is significant for applications subject to RoHS regulations.

Q: Do these resistors have identical temperature performance? A: Yes. Both components operate across -55°C to 350°C with a temperature coefficient of ±260ppm/°C, ensuring equivalent thermal stability in the specified operating range.

Q: What mounting compatibility exists between these parts? A: Both components feature identical mounting specifications: flange braces with right-angle orientation, solder lugs for connection, and radial flat oval package configuration. Direct mechanical substitution is possible without redesign of mounting hardware.