RT100AS4R40KB Equivalent & Substitute Parts

Part Overview

The RT100AS4R40KB is a 4.4 Ohm, 100W wirewound potentiometer manufactured by Vishay Sfernice, designed for panel mount applications with solder lug termination. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing system maintenance and new design implementations. The part's primary function as a precision resistive element in high-power applications necessitates careful evaluation of alternative components that maintain electrical and mechanical compatibility.

Substiute Parts

RT100AS4R40KB

Vishay SferniceIn Stock: 1188RT100AS4R40KB Datasheet

Current PartRFQ

RJS4R0E

OhmiteIn Stock: 1133RJS4R0E Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the RT100AS4R40KB is determined by the following critical parameters:

Electrical Compatibility Criteria:

• Resistance value within ±10% tolerance band (4.4 Ohm nominal)
• Power rating sufficient for application requirements
• Wirewound construction for thermal stability
• Single-turn configuration

Mechanical Compatibility Criteria:

• Panel mount configuration
• Solder lug termination style
• 300° rotation specification
• Compatible actuator dimensions and mounting interface

The RJS4R0E from Ohmite qualifies as a substitute based on shared electrical characteristics (wirewound, single-turn, solder lug termination, panel mount) and mechanical form factor. However, specific parameter deviations exist that must be evaluated for application suitability.

Parameter Comparison

Engineering Selection Recommendations

The RJS4R0E represents an available substitute for the obsolete RT100AS4R40KB. Selection of this alternative requires evaluation of the following factors:

Power Rating Consideration: The RJS4R0E is rated at 50W, compared to the original part's 100W rating. Applications requiring the full 100W dissipation capacity cannot use this substitute without thermal management modifications or circuit redesign.

Resistance Value Deviation: The RJS4R0E provides 4 Ohms nominal resistance versus 4.4 Ohms in the original specification. Both values fall within the ±10% tolerance band, resulting in a 9.1% difference between nominal values. Circuit performance impact depends on application sensitivity to this resistance variance.

Mechanical Interface Differences: The RJS4R0E features a flatted actuator type with slightly different dimensional specifications (0.250" diameter versus 0.236", and 0.875" length versus 0.984"). Panel cutout and mechanical coupling compatibility must be verified for the specific application.

Compliance Status: The RJS4R0E carries ROHS3 compliance certification and active product status, ensuring ongoing availability and regulatory alignment for new designs.

Frequently Asked Questions (FAQ)

Q: Can the RJS4R0E directly replace the RT100AS4R40KB in all applications?

A: Direct replacement is limited by power rating and resistance value differences. The RJS4R0E's 50W rating is insufficient for applications requiring 100W dissipation. The 4 Ohm versus 4.4 Ohm difference may impact circuit performance depending on application tolerance. Mechanical actuator differences require verification of panel mounting compatibility.

Q: What is the resistance tolerance impact of substitution?

A: Both parts specify ±10% tolerance. The nominal difference of 0.4 Ohms (9.1% variance) falls within typical circuit design margins for general applications but may be significant in precision current-limiting or load-balancing circuits.

Q: Are there packaging or inventory considerations?

A: The RJS4R0E is supplied in bulk packaging and maintains active product status with 1030 pieces in stock. The original RT100AS4R40KB is obsolete with 1166 pieces available as remaining inventory. Long-term design decisions should prioritize the active RJS4R0E to ensure supply chain continuity.

Q: How do the actuator dimensions affect mechanical compatibility?

A: The RJS4R0E features a flatted actuator (0.250" diameter, 0.875" length) compared to the round actuator (0.236" diameter, 0.984" length) of the original part. Panel cutout geometry and coupling mechanism compatibility must be confirmed before substitution. Slight dimensional variations may require mechanical adapter evaluation.

Q: What certifications apply to the substitute part?

A: The RJS4R0E is ROHS3 compliant and classified as EAR99 for export control purposes. The original RT100AS4R40KB does not specify RoHS compliance status. Applications requiring regulatory compliance should reference the RJS4R0E's certification documentation.