Hammond Manufacturing 140M Audio Transformer Equivalent & Substitute Parts

Part Overview

The Hammond Manufacturing 140M is a shielded audio transformer designed for chassis mount applications with 100k ohm primary impedance and 1.5k ohm secondary impedance. This component operates across a 70Hz to 11kHz frequency range with an 8:1 turns ratio. The 140M is classified as obsolete, making identification of suitable substitute components essential for ongoing system maintenance and new design implementations where this transformer specification is required.

Substiute Parts

140M

Hammond ManufacturingIn Stock: 791140M Datasheet

Current PartRFQ

140MEX

Hammond ManufacturingIn Stock: 793140MEX Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The Hammond Manufacturing 140MEX qualifies as a direct substitute for the 140M based on the following critical parameters:

Matching Parameters:

• Primary impedance: 100k ohms (identical)
• Secondary impedance: 1.5k ohms (identical)
• Transformer type: Shielded (identical)
• Mounting type: Chassis Mount (identical)
• Physical dimensions: 1.250" Dia × 1.000" height (identical)
• RoHS3 compliance (identical)

Allowable Variations:

• Turns ratio: 8:1 (140M) versus 8.13:1 (140MEX) — within acceptable tolerance for audio transformer applications
• Frequency range: 70Hz ~ 11kHz (140M) versus 20Hz ~ 20kHz (140MEX) — substitute provides extended bandwidth
• Termination style: Wire Leads (140M) versus Screw Terminal (140MEX) — mechanical interface difference requiring installation consideration

Parameter Comparison

Engineering Selection Recommendations

The 140MEX is the appropriate substitute for the obsolete 140M. Both components maintain identical primary and secondary impedance specifications and physical form factors required for direct mechanical replacement in chassis mount applications. The 140MEX carries active product status, ensuring ongoing availability and supply chain continuity.

Both parts satisfy ROHS3 compliance and REACH unaffected status, meeting current regulatory requirements for electronic component deployment. The 140MEX provides additional performance data including DC resistance measurements, isolation voltage rating, and insertion/return loss specifications not documented for the original 140M.

The primary consideration for implementation is the termination interface change from wire leads to screw terminals, which requires modification of the connection methodology but does not affect electrical performance or mechanical fit within the chassis mount envelope.

Frequently Asked Questions (FAQ)

Q: Can the 140MEX directly replace the 140M without circuit modification?

A: The 140MEX maintains identical impedance and frequency response characteristics within the operating range of the 140M. The primary difference is termination style: the 140M uses wire leads while the 140MEX uses screw terminals. Connection methodology must be adapted accordingly, but no circuit modifications are required.

Q: What is the significance of the turns ratio difference between 8:1 and 8.13:1?

A: The 0.13:1 variation represents a 1.625% difference in turns ratio. For audio transformer applications with ±1dB frequency response specification, this variance falls within acceptable tolerance and does not require circuit compensation.

Q: Does the 140MEX provide improved performance over the 140M?

A: The 140MEX extends the frequency range from 70Hz ~ 11kHz to 20Hz ~ 20kHz, providing broader bandwidth capability. Additional performance metrics including 500Vrms isolation voltage, 1.2dB typical insertion loss, and 30dB typical return loss are specified for the 140MEX but not documented for the 140M.

Q: Are there any compliance or certification differences between these parts?

A: Both the 140M and 140MEX maintain identical RoHS3 compliance, REACH unaffected status, and EAR99 ECCN classification. No compliance barriers exist for substitution.

Q: What inventory considerations apply to these components?

A: The 140M is classified as obsolete with 713 pieces in stock. The 140MEX is an active product with 764 pieces in stock, providing assured long-term availability for new implementations and ongoing system support.