MET-11 Audio Transformer Equivalent & Substitute Parts

Part Overview

The MET-11 is an active audio transformer manufactured by Tamura, designed for data/voice coupling applications. It features a 10kCT primary impedance and 2kCT secondary impedance with a 2.23:1 turns ratio, operating across the 300Hz to 100kHz frequency range. The component is packaged in through-hole configuration with PC pin termination and is RoHS compliant. Finding equivalent substitute parts is necessary to ensure supply chain continuity, optimize procurement costs, and maintain design flexibility across manufacturing batches.

Substiute Parts

MET-11

TamuraIn Stock: 1038MET-11 Datasheet

Current PartRFQ

SP-21

Triad MagneticsIn Stock: 1340SP-21 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MET-11 is determined by strict alignment of the following electrical and mechanical parameters:

Primary Electrical Criteria:

• Impedance matching: Primary impedance 10kCT and secondary impedance 2kCT
• Turns ratio within acceptable tolerance: 2.23:1 ± acceptable variance
• Frequency range coverage: 300Hz ~ 100kHz minimum
• Frequency response: ±2dB specification
• DC resistance values: Primary 1kOhm ± tolerance, Secondary 300Ohm ± tolerance
• Power level rating: Minimum 40mW

Mechanical Criteria:

• Mounting type: Through Hole required
• Termination style: PC Pin required
• Physical dimensions: Compatible with 0.409" L x 0.310" W footprint and 0.465" maximum seated height
• Packaging compatibility: Tube or Bulk acceptable for equivalent substitution

Compliance Criteria:

• RoHS compliance status (RoHS or ROHS3 acceptable)
• Active product status
• ECCN classification: EAR99

The SP-21 from Triad Magnetics qualifies as a direct substitute based on matching all primary electrical parameters, mechanical mounting specifications, and compliance requirements.

Parameter Comparison

Engineering Selection Recommendations

MET-11 (Tamura) - Primary Selection

The MET-11 remains the primary component choice when available. It is an active product with confirmed RoHS compliance and established supply inventory of 1012 pieces. The component meets all specified electrical and mechanical requirements for data/voice coupling applications within the 300Hz to 100kHz frequency band.

SP-21 (Triad Magnetics) - Qualified Substitute

The SP-21 qualifies as a direct substitute for the MET-11 based on electrical and mechanical parameter alignment. Key advantages of the SP-21 include:

• Higher power level rating (50mW vs. 40mW), providing additional thermal margin
• Enhanced voltage isolation rating (1000VRMS vs. 500VRMS), suitable for higher isolation requirements
• Extended operating temperature range (-40°C to 85°C vs. -20°C to 85°C), enabling deployment in lower temperature environments
• ROHS3 compliance status, meeting current regulatory requirements
• Confirmed inventory availability of 1317 pieces

The SP-21 maintains identical impedance specifications, frequency response characteristics, and physical form factor compatibility. The turns ratio variance of 0.45% and DCR variances (5% primary, 10% secondary) fall within acceptable engineering tolerances for audio transformer applications.

Substitution Constraints

Substitution between MET-11 and SP-21 is valid only when the following conditions are met:

• Circuit design accommodates the SP-21's higher isolation voltage rating
• PCB layout and mechanical assembly accept the SP-21's identical physical dimensions
• Application does not require the specific transformer type designation (Data/Voice vs. Audio Coupling)
• Compliance documentation reflects the substitute part number and manufacturer

Frequently Asked Questions (FAQ)

Q: Can the SP-21 be used as a direct replacement for the MET-11 in existing designs?

A: Yes. The SP-21 meets all critical electrical parameters (impedance, turns ratio, frequency response) and mechanical specifications (mounting, termination, dimensions) required for direct substitution. The SP-21's higher power rating and isolation voltage provide additional design margin.

Q: What is the significance of the 0.45% turns ratio variance between MET-11 (2.23:1) and SP-21 (2.24:1)?

A: The variance is negligible for audio transformer applications. Both transformers operate within the ±2dB frequency response specification, indicating that the impedance matching and signal coupling characteristics remain functionally equivalent across the 300Hz to 100kHz operating band.

Q: Are there differences in DC resistance that affect circuit performance?

A: The SP-21 exhibits 5% higher primary DCR (1.05kOhm vs. 1kOhm) and 10% higher secondary DCR (330Ohm vs. 300Ohm). These variances are within standard transformer manufacturing tolerances and do not materially affect audio coupling or data/voice transmission performance in typical circuit configurations.

Q: Does the SP-21's higher isolation voltage rating (1000VRMS vs. 500VRMS) create compatibility issues?

A: No. Higher isolation voltage ratings are backward compatible and do not create circuit incompatibility. The SP-21 is suitable for applications requiring either 500VRMS or 1000VRMS isolation specifications.

Q: What is the impact of the extended operating temperature range of the SP-21 (-40°C to 85°C vs. -20°C to 85°C)?

A: The SP-21's wider temperature range provides additional flexibility for deployment in temperature-controlled and non-temperature-controlled environments. Applications limited to -20°C to 85°C operation remain fully compatible with the SP-21.

Q: Are there packaging differences between MET-11 and SP-21?

A: Yes. The MET-11 is supplied in Tube packaging, while the SP-21 is supplied in Bulk packaging. Both packaging formats are acceptable for equivalent substitution; however, procurement and handling procedures may differ based on packaging type.

Q: Do both parts meet current RoHS compliance requirements?

A: Yes. The MET-11 is RoHS Compliant, and the SP-21 is ROHS3 Compliant. Both meet current regulatory requirements for lead-free and restricted substance compliance.

Q: Can the MET-11 and SP-21 be mixed within the same production batch?

A: Mixing is permissible only when circuit design and compliance documentation explicitly authorize substitution. Production traceability and bill-of-materials records must clearly identify which transformer type is installed in each unit.

Q: What inventory considerations apply when selecting between MET-11 and SP-21?

A: The MET-11 has 1012 pieces in stock, while the SP-21 has 1317 pieces available. Procurement decisions should account for lead times, supply chain stability, and long-term availability of each manufacturer's product line.