EJ14 Trimmer Capacitor Equivalent & Substitute Parts

Part Overview

The EJ14 is a 0.8–14pF trimmer capacitor manufactured by Knowles Voltronics, designed for side-adjustment applications in surface mount configurations. Rated for 125V operation with PTFE dielectric material, this component is classified as obsolete. Due to its obsolete status, identifying functionally equivalent substitute parts is essential for design continuity, production support, and system maintenance. The AJ14 serves as a direct functional alternative, offering comparable electrical performance with modified mounting and dielectric specifications.

Key Parameters

Parameter	EJ14 Specification
Capacitance Range	0.8 – 14pF
Voltage Rating	125V
Adjustment Type	Side
Dielectric Material	Polytetrafluoroethylene (PTFE)
Q Factor @ 100MHz	3000
Physical Diameter	0.300" (7.62mm)
Maximum Height	0.500" (12.70mm)
Operating Temperature Range	–65°C to 125°C
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the EJ14 is determined by the following critical parameters:

Capacitance Range Overlap: The substitute must cover the required tuning range. The EJ14 operates from 0.8–14pF; the AJ14 operates from 1–14pF, providing 99.3% overlap with a 0.2pF minimum offset.
Voltage Rating: Both parts are rated 125V, ensuring equivalent electrical stress handling.
Adjustment Mechanism: Both employ side-adjustment, maintaining identical tuning interface and mechanical compatibility.
Q Factor: Both maintain 3000 @ 100MHz, preserving frequency response and loss characteristics.
Physical Envelope: Identical diameter (0.300") and height (0.500") ensure mechanical fit in existing designs.
Operating Temperature: Both support –65°C to 125°C, maintaining thermal performance equivalence.
Mounting Transition: The primary difference is mounting type: EJ14 is surface mount; AJ14 is through-hole. This represents a design-level change requiring PCB layout modification.

Parameter Comparison

Parameter	EJ14	AJ14	Compatibility Notes
Capacitance Range	0.8 – 14pF	1 – 14pF	AJ14 minimum is 0.2pF higher; acceptable for most applications
Voltage Rating	125V	125V	Equivalent
Adjustment Type	Side	Side	Equivalent
Q Factor @ 100MHz	3000	3000	Equivalent
Physical Diameter	0.300" (7.62mm)	0.300" (7.62mm)	Equivalent
Maximum Height	0.500" (12.70mm)	0.500" (12.70mm)	Equivalent
Operating Temperature	–65°C to 125°C	–65°C to 125°C	Equivalent
Mounting Type	Surface Mount	Through Hole	Requires PCB redesign
Dielectric Material	PTFE	Air	Different materials; both support equivalent electrical performance
Product Status	Obsolete	Active	AJ14 is actively manufactured

Engineering Selection Recommendations

Primary Substitute: AJ14

The AJ14 is the direct functional equivalent to the EJ14 based on electrical parameters, mechanical envelope, and adjustment characteristics. Selection of the AJ14 is supported by:

Active product status ensures ongoing availability and manufacturing consistency
RoHS3 compliance and REACH unaffected status meet modern regulatory requirements
Identical electrical performance (voltage, Q factor, temperature range) across the specified capacitance range
Mechanical compatibility in physical dimensions and adjustment mechanism

Design Consideration: Transition from surface mount (EJ14) to through-hole (AJ14) requires PCB layout modification. The dielectric material change from PTFE to air does not impact electrical equivalence for this application category.

Frequently Asked Questions (FAQ)

Q: Can the AJ14 directly replace the EJ14 without PCB modification?

A: No. The EJ14 is surface mount; the AJ14 is through-hole. PCB layout and footprint changes are required. The electrical and mechanical parameters are equivalent, but the mounting interface differs fundamentally.

Q: What is the capacitance range difference between EJ14 and AJ14?

A: The EJ14 ranges from 0.8–14pF; the AJ14 ranges from 1–14pF. The 0.2pF offset at minimum capacitance is negligible for most tuning applications and does not affect functional equivalence.

Q: Are there compliance differences between EJ14 and AJ14?

A: Yes. The AJ14 carries RoHS3 compliance and REACH unaffected status. The EJ14, being obsolete, does not list these certifications. For new designs or regulated applications, the AJ14 is the preferred choice.

Q: Does the dielectric material change from PTFE to air affect performance?

A: Both PTFE and air dielectrics support the specified Q factor of 3000 @ 100MHz and voltage rating of 125V. The material change does not compromise electrical equivalence for this trimmer capacitor application.

Q: Is the AJ14 suitable for high-frequency applications?

A: Yes. The AJ14 maintains a Q factor of 3000 @ 100MHz, identical to the EJ14, supporting equivalent performance in RF and microwave tuning circuits.

Q: What is the inventory status of these parts?

A: EJ14: 725 pieces in stock (new original). AJ14: 834 pieces in stock (new original, bulk packaging).

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