Ohmite F30J25R Wirewound Chassis Mount Resistor - Equivalent & Substitute Parts

Part Overview

The Ohmite F30J25R is a 25 Ohms ±5% 30W wirewound chassis mount resistor from the Stackohm® 250 series. This component is designed for high-power applications requiring stable resistance values across extended temperature ranges. The part is currently active in production with 871 units in stock. Substitute parts are identified to address application requirements for higher power dissipation or improved compliance specifications while maintaining core electrical and mechanical compatibility.

Substiute Parts

F30J25R

OhmiteIn Stock: 981F30J25R Datasheet

Current PartRFQ

F55J25R

OhmiteIn Stock: 1246F55J25R Datasheet

UpgradeRFQ

F30J25RE

OhmiteIn Stock: 809F30J25RE Datasheet

Parametric EquivalentRFQ

F30J25RE

OhmiteIn Stock: 809F30J25RE Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the F30J25R are identified based on strict electrical and mechanical parameter matching within the Stackohm® 250 series. Substitution eligibility is determined by the following criteria:

Primary Matching Parameters:

• Resistance value: 25 Ohms
• Tolerance: ±5%
• Composition: Wirewound
• Temperature Coefficient: ±260ppm/°C
• Operating Temperature Range: -55°C to 350°C
• Coating/Housing Type: Vitreous Enamel Coated
• Mounting Feature: Flange Braces, Right Angle
• Lead Style: Solder Lugs
• Package/Case: Radial, Flat Oval

Allowable Variation:

• Power rating may increase to accommodate higher dissipation requirements
• Physical dimensions may scale proportionally with power rating
• RoHS compliance status may differ between variants

The F55J25R represents an upgrade option with increased power capacity (55W vs. 30W), suitable for applications requiring higher thermal dissipation while maintaining identical electrical characteristics. The F30J25RE provides a parametric equivalent with identical power rating and dimensions, with improved RoHS compliance.

Parameter Comparison

Engineering Selection Recommendations

F30J25RE Selection Criteria: The F30J25RE is a direct parametric equivalent to the F30J25R with identical electrical specifications and physical dimensions. Selection of F30J25RE is appropriate when RoHS compliance is required. Both parts maintain the same power rating, resistance value, and thermal characteristics. The F30J25RE carries RoHS Compliant status with MSL rating of 1 (Unlimited), providing improved environmental compliance without electrical or mechanical trade-offs.

F55J25R Selection Criteria: The F55J25R is suitable for applications where the 30W power rating of the F30J25R is insufficient. This upgrade maintains all electrical parameters while increasing power dissipation capacity to 55W. The increased physical length (4.600" vs. 1.250") accommodates the higher power rating. Selection of F55J25R is appropriate when thermal margin requirements exceed the capabilities of the 30W variant. Physical space availability must be confirmed prior to substitution due to the increased length dimension.

Frequently Asked Questions (FAQ)

Q: Can F30J25RE be used as a direct replacement for F30J25R? A: Yes. The F30J25RE maintains identical resistance (25 Ohms), tolerance (±5%), power rating (30W), temperature coefficient (±260ppm/°C), operating temperature range (-55°C to 350°C), and physical dimensions (1.250" L x 1.000" W). The primary difference is improved RoHS compliance status.

Q: When should F55J25R be selected instead of F30J25R? A: The F55J25R should be selected when circuit analysis indicates power dissipation exceeding 30W. The 55W rating provides increased thermal margin. Verify available mounting space accommodates the increased length of 4.600" compared to 1.250" for the F30J25R.

Q: Are all three parts mechanically interchangeable? A: F30J25R and F30J25RE are mechanically interchangeable with identical dimensions and mounting features. F55J25R has increased length (4.600" vs. 1.250") and requires verification of available board space before substitution.

Q: What is the temperature coefficient significance for these resistors? A: All three parts share a temperature coefficient of ±260ppm/°C across the operating range of -55°C to 350°C. This specification defines resistance value drift relative to temperature changes and is identical across all substitute options.

Q: Does RoHS compliance affect electrical performance? A: No. RoHS compliance status reflects manufacturing process and material composition but does not alter electrical characteristics. F30J25RE and F30J25R are electrically identical despite different compliance ratings.

Q: What is the significance of the Stackohm® 250 series designation? A: Stackohm® 250 is the product series identifier for all three parts, indicating they share common design architecture, thermal characteristics, and performance specifications within this family of wirewound chassis mount resistors.