4307R-185J Delevan 4307R-185J RF Inductor — Molded, Shielded, Axial

Delevan 4307R-185J RF Inductor Overview

The Delevan 4307R-185J is a high-reliability, molded shielded RF inductor designed for precision filtering, impedance matching, and energy storage in RF and mixed-signal circuits. Belonging to Delevan’s 4307R Series, it combines a ferrite core and sleeve within a robust epoxy-molded package to minimize magnetic coupling and radiated emissions while maintaining stable inductance across temperature and current. The “R” designation indicates the series variant with ferrite sleeve shielding, and the “J” suffix denotes a tight ±5% tolerance—ideal when you need consistent behavior across production lots.

At the heart of the 4307R-185J is a precisely wound coil delivering 1.8 mH nominal inductance with Q ≥ 50 (tested at 250 kHz), and a self-resonant frequency (SRF) of 2.6 MHz for clean RF performance. The component supports 105 mA max DC current, with a maximum DC resistance (DCR) of 29.9 Ω, balancing energy storage and insertion loss for low-power RF front ends, precision IF stages, and sensitive sensor interfaces. Its axial, through-hole leaded form factor speeds prototyping and supports PCB mounting where mechanical robustness and easy inspection are required.

Mechanically, the part measures ≈11.35 mm length × 5.00 mm diameter (max envelope), with AWG #22 tin-coated copper leads cut long for flexible board insertion. The epoxy molded body guards the ferrite core and sleeve against shock and humidity, while the sleeve’s inherent magnetic shielding significantly reduces mutual coupling in tight layouts—critical in compact RF modules, tuners, and analog front ends. Rated operation from –55°C to +125°C, the series adheres to MIL-PRF-15305 test methods for performance verification. Devices are tape-and-reel packaged for automated assembly.

Why engineers choose the 4307R-185J

• Predictable RF behavior: High Q at the specified test frequency and a clearly defined SRF simplify network synthesis and stability analysis.

• Lower magnetic radiation: The ferrite sleeve and molded body reduce stray fields versus open-wound parts, protecting adjacent high-impedance nodes.

• Production-friendly: Axial leads, generous lead length, clear body marking, and reel packaging align with through-hole automation and inspection practices.

Key Features

Stable, low-loss inductance where it counts

With Q ≥ 50 at the specified test frequency, the 4307R-185J limits resistive losses, helping keep insertion loss low in RF filters and resonant tanks. This is particularly valuable in IF filters, sensor signal conditioning, and low-power receivers, where fractional dB matter. The 2.6 MHz SRF gives ample headroom for 1.8 mH applications in low-MHz networks or as high-impedance chokes isolating RF from baseband domains.

Shielded ferrite sleeve = fewer layout headaches

Unshielded inductors can couple energy into nearby traces and components, skewing filter skirts or allowing unwanted oscillations. The ferrite core and sleeve inside a molded epoxy case provide inherent magnetic shielding, 3% max coupling part-to-part within the series, and a compact, repeatable magnetic footprint—making it easier to route sensitive nodes or stack multiple LC sections without crosstalk.

Built for harsh environments and standards-driven designs

The 4307R family is qualified with MIL-PRF-15305 test methods, offers –55°C to +125°C operation, and is marked for traceability (front and reverse, with inductance value, tolerance, and date code). An “R” before the date code indicates a RoHS component, aligning with environmental compliance needs. Power dissipation at 90°C is characterized (0.385 W), and current ratings are defined at 90°C ambient with 35°C rise to give realistic thermal guidance.

Thoughtful mechanical design for assembly

The part’s axial leads (AWG #22 TCW) and long lead length (≈33.5–39.6 mm) simplify board insertion—including double-sided assemblies where form/fit adjustments are helpful. The length (≈10.85–11.35 mm) and diameter (≈4.50–5.00 mm) suit dense through-hole layouts, while tape-and-reel delivery (12″ and 14″ reels) supports automated lead forming and insertion equipment.

Specifications of Delevan 4307R-185J Inductor

Note: Values such as SRF, DCR, Q, and current rating are value-dependent within the 4307R series; the entries above correspond to the 1.8 mH (“-185”) selection with J tolerance.

Applications

RF & IF filtering

In superheterodyne receivers, the 4307R-185J can serve in IF band-pass filters or LC resonant tanks where tight tolerance and high Q maintain passband flatness and steep skirts. The shielded construction keeps mutual coupling low when multiple stages are placed in proximity—helpful in compact radios and instrumentation.

Bias tees and RF chokes

As a high-impedance choke at low-MHz frequencies, the part isolates DC bias rails from RF paths. The 2.6 MHz SRF ensures the inductor behaves inductively in the intended operating band while the 29.9 Ω DCR limits series loss where DC drop must be managed.

Sensor and precision analog front ends

Low-noise current sources, bridge sensor excitation lines, and loop-powered transmitters benefit from the 4307R-185J’s predictable inductance and shielded body, which reduce interference with sensitive high-impedance nodes and precision amplifiers.

EMC/EMI suppression in mixed-signal boards

Placed between noisy switching domains and analog/RF sections, the inductor functions as a broadband choke that—combined with local capacitance—forms effective π-filters. The ferrite sleeve limits field radiation, reducing risk of layout-induced emissions.

Education, prototyping, and test

The axial lead format and long leads make the 4307R-185J easy to breadboard or socket for filter prototyping, enabling quick iteration of L-C networks without re-spinning PCBs. Tape-and-reel support streamlines transfer from concept to production.

Design & Implementation Notes

1. Operating point vs. linearity: The series specifies incremental current as the DC current that changes inductance by up to 5%. Keep AC ripple and DC bias well below this threshold to maintain filter center frequency and Q.

2. SRF margining: Always place your operating frequency well below the 2.6 MHz SRF for a 1.8 mH value to ensure inductive behavior and avoid parasitic capacitance effects.

3. Thermal budgeting: The 105 mA rating is defined at 90°C ambient with 35°C rise; derate in higher ambient or restricted airflow conditions. The series 0.385 W dissipation data at 90°C provides a sanity check for thermal simulations.

4. Layout spacing: Even with shielding, observe sensible spacing between high-Q inductors and high-impedance amplifier inputs. Align the axial axis to minimize loop area in surrounding traces.

5. Marking & compliance: Production control is aided by clear marking (value, tolerance, date code). For RoHS builds, note the “R” preceding the date code convention on compliant units.

6. Test alignment: If you validate Q, use a 250 kHz fixture for correlation to datasheet numbers on this value; account for fixture parasitics near the SRF.

Three Highlighted Benefits

• Consistent filter performance: Tight ±5% tolerance and high Q stabilize center frequencies and insertion loss.

• Lower EMI risk: Ferrite sleeve shielding cuts stray fields and crosstalk in dense RF layouts.

• Rugged and production-ready: Epoxy molding, long axial leads, and tape-and-reel packaging support automated insertion and long-term reliability.

Ordering Information

• Part: 4307R-185J

• Description: Molded, shielded RF inductor, 1.8 mH, ±5%

• Form Factor: Axial leaded, PCB mount

• Packaging: Reel (12″ up to 2500 pcs; 14″ up to 3000 pcs) for automated assembly.

Summary

The Delevan 4307R-185J offers 1.8 mH of tightly controlled inductance in a compact, molded shielded axial package—engineered for low loss, low coupling, and wide temperature operation. Whether you are tuning an IF filter, building a bias tee, or isolating mixed-signal domains, this device provides the repeatability and electromagnetic discipline that RF designs demand—backed by MIL-PRF-15305 test methodology and production-friendly packaging and markings.