Ohmite 43F300 Equivalent & Substitute Parts

Part Overview

The Ohmite 43F300 is a 300 Ohm ±1% 3W axial wirewound through-hole resistor from the Ohmicone® 40 series. This component is classified as Active and remains in production. Equivalent and substitute parts are identified when component availability is limited, supply chain disruptions occur, or design flexibility permits alternative sourcing while maintaining electrical and mechanical compatibility.

Substiute Parts

43F300

OhmiteIn Stock: 77543F300 Datasheet

Current PartRFQ

ALSR03300R0FE12

Vishay DaleIn Stock: 935ALSR03300R0FE12 Datasheet

DirectRFQ

RS02B300R0FS70

Vishay DaleIn Stock: 1703RS02B300R0FS70 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the Ohmite 43F300 are qualified based on the following electrical and mechanical parameters:

• Resistance value: 300 Ohms (exact match required)
• Tolerance: ±1% (exact match required)
• Power rating: 3W (exact match required)
• Composition: Wirewound (exact match required)
• Package: Axial through-hole (exact match required)
• Termination count: 2 (exact match required)

The substitute parts listed below meet all core electrical specifications. Physical dimensions and temperature coefficients may vary within acceptable ranges for axial wirewound resistors. Compliance certifications and moisture resistance features differ and are noted in the comparison table.

Parameter Comparison

Engineering Selection Recommendations

All three resistors meet the core electrical requirements of 300 Ohms ±1% at 3W with wirewound axial construction. Selection among these parts should be based on regulatory compliance and environmental requirements:

The Vishay Dale ALSR03300R0FE12 is RoHS3 compliant and suitable for applications requiring lead-free construction. This part features moisture-resistant construction and operates across -65°C to 250°C.

The Vishay Dale RS02B300R0FS70 is the manufacturer-recommended substitute. It maintains the ±20ppm/°C temperature coefficient matching the original Ohmite part and includes moisture-resistant features. This part is REACH Affected and RoHS non-compliant, matching the regulatory status of the original component.

The Ohmite 43F300 remains the primary specification. Substitution should occur only when supply constraints or design requirements necessitate alternative sourcing.

Frequently Asked Questions (FAQ)

Q: Can the Vishay Dale ALSR03300R0FE12 be used as a direct replacement for the Ohmite 43F300?

A: Yes, electrically and mechanically. The ALSR03300R0FE12 matches all core specifications: 300 Ohms ±1%, 3W, wirewound, axial package. Physical dimensions are slightly smaller (0.180" Dia vs 0.220" Dia). The temperature coefficient is ±30ppm/°C versus ±20ppm/°C. RoHS3 compliance differs from the original part's non-compliant status.

Q: What is the difference between the two Vishay Dale substitutes?

A: Both are 300 Ohm ±1% 3W axial wirewound resistors with moisture-resistant features. The RS02B300R0FS70 matches the original ±20ppm/°C temperature coefficient, while the ALSR03300R0FE12 has ±30ppm/°C. Physical dimensions differ slightly. The RS02B300R0FS70 is supplied in Cut Tape format with higher inventory (1691 Pcs vs 877 Pcs). The ALSR03300R0FE12 is RoHS3 compliant; the RS02B300R0FS70 is not.

Q: Are physical dimension differences significant?

A: Axial resistor dimensions vary within standard tolerances across manufacturers. The Ohmite 43F300 measures 0.220" Dia x 0.594" L. Substitutes measure 0.180" Dia x 0.500" L (ALSR) and 0.187" Dia x 0.560" L (RS02B). Verify PCB layout and mechanical clearances before substitution.

Q: Which substitute should I select for RoHS-compliant applications?

A: The Vishay Dale ALSR03300R0FE12 is RoHS3 compliant. The original Ohmite 43F300 and Vishay Dale RS02B300R0FS70 are both RoHS non-compliant.

Q: What is the temperature coefficient significance?

A: The Ohmite 43F300 and Vishay Dale RS02B300R0FS70 both specify ±20ppm/°C. The ALSR03300R0FE12 specifies ±30ppm/°C. For applications with tight tolerance requirements across temperature ranges, the ±20ppm/°C parts are preferred.