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RFMW offers Frontier Electronics’ 5SQ super-high-Q tunable-inductor family, including the 5SQ-03A (503025-008-00). RFMW describes the family as covering 0.0275–0.53 µH, with self-resonant frequencies of 450–1450 MHz and Q values reaching 100 on some models. Frontier also catalogs a smaller SMD RF tunable-coil family, 5SQSMD, with 28.5–465 nH inductance in a 5.9 × 6.3 × 7.5 mm package.
What RFMW offers from Frontier
RFMW’s listing identifies Frontier Electronics as the manufacturer of the 5SQ series and describes the 5SQ-03A as a “5 Super High Q Tunable Inductor, 3.5T.” The “3.5T” designation refers to the coil’s tuning construction; it is not a substitute for checking the exact electrical specification of the part number you plan to use.
The 5SQ range includes 5SQ-01A, 5SQ-02A, 5SQ-03, 5SQ-03A, 5SQ-05, 5SQ-05A and 5SQ-08. RFMW states that the series offers the highest Q in the industry, with Q up to 100 for some models. That wording is a Frontier/RFMW vendor claim, not an independently verified industry ranking.
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5SQ electrical range and the numbers that matter
RFMW gives these family-level figures:
| Characteristic | 5SQ family information | How to apply it |
|---|---|---|
| Inductance | 0.0275–0.53 µH (27.5–530 nH) | Use the individual model’s minimum, nominal and maximum values for tuning and tolerance calculations. |
| Self-resonant frequency | 450–1450 MHz | Keep the selected part’s self-resonant frequency comfortably above the operating band; parasitic capacitance makes an inductor unsuitable beyond resonance. |
| Q | Up to 100 for some models | Compare Q at the test frequency relevant to your circuit rather than treating the family maximum as universal. |
| Compliance | RFMW describes the family as RoHS compliant | Confirm the compliance status and revision for the exact orderable part. |
Model-specific inductance and Q are not interchangeable across the 5SQ variants. Before a substitution, obtain the exact RFMW part page or Frontier datasheet and verify the tuning range, test frequency, tolerances, package details and current ordering code.
#1 Best Overall
- 【Adjustable Range】Easily fine tune inductance from 0.6uH to 1.7uH, with a minimum core value of 1.6uH and inductance at 0.5uH for versatile circuit applications.
- 【Precision Winding】Features a 12 turn winding design that supports accurate adjustments in electronic circuits requiring fine tuning.
- 【Features】Optimized for high performance, suitable for frequencies between 25MHz and 100MHz, making it ideal for RF and communication projects.
- 【 Package】Includes a pack of 10 adjustable ferrite core inductors, for prototyping, repairs, or DIY project needs.
- 【 Material】Constructed with PP housing and ferrite core (3.6mm diameter, 8mm height) to ensure stable and reliability.
What the 5SQ-03A is used for
The tunable construction lets a designer adjust inductance during alignment or production while retaining a high-Q RF component. RFMW lists these applications:
- Low-pass filters, where low insertion loss can reduce roll-off near the cutoff.
- High-pass and band-pass filters that need adjustable resonant points.
- Diplexers, where RFMW highlights temperature stability as a design benefit.
- Tuner circuits for matching or frequency alignment.
- Oscillators whose frequency depends on an adjustable LC network.
In each case, select the part from the circuit’s actual frequency, required inductance window and acceptable loss. A high Q at one measurement frequency does not guarantee the same Q at your operating frequency.
Rank #2
- 【Precision Winding】Features a 12 turn winding design that supports accurate adjustments in electronic circuits requiring fine tuning.
- 【 Material】Constructed with PP housing and ferrite core (3.6mm diameter, 8mm height) to ensure stable and reliability.
- 【 Package】Includes a pack of 10 adjustable ferrite core inductors, for prototyping, repairs, or DIY project needs.
- 【Features】Optimized for high performance, suitable for frequencies between 25MHz and 100MHz, making it ideal for RF and communication projects.
- 【Adjustable Range】Easily fine tune inductance from 0.6uH to 1.7uH, with a minimum core value of 1.6uH and inductance at 0.5uH for versatile circuit applications.
Comparing 5SQ variants
The family name alone is not enough to choose a replacement. Use the following comparison axes for every candidate:
- Q at the operating frequency: read the model’s test conditions and compare like-for-like.
- Inductance limits: check minimum, nominal and maximum values across the available tuning travel.
- Self-resonant frequency: leave margin above the highest frequency where the inductor will operate.
- Mechanical form: confirm footprint, height, adjustment access and the number of tuning turns.
- Circuit loss and stability: evaluate insertion loss, temperature drift and the effect on filter or oscillator alignment.
- Procurement identity: match the manufacturer code, RFMW part number and compliance documentation.
RFMW’s family range should therefore be treated as a map of available options, not as the specification of every 5SQ model. The 5SQ-03A’s 0.0275–0.53 µH and 450–1450 MHz figures are family-level ranges; they do not state the 5SQ-03A’s individual endpoints.
Rank #3
- It has a wide range of applications in radio communication
- It belongs to the inductance of class uh
- Typical use in the LC oscillation frequency regulation; radio remote control transmitter, coupled inductors, and so on
- The surface and internal structure are very delicate.
- For detailed specifications and matching models, please see the detailed introduction in the description section.
Frontier 5SQSMD RF tunable coils
For surface-mount designs, Frontier’s magnetic-components catalog lists the 5SQSMD family under “SMD RF TUNABLE COILS.” The catalog gives a package size of 5.9 × 6.3 × 7.5 mm and an inductance range of 28.5–465 nH.
| Family | Mounting format | Catalog inductance information | Catalog dimensions |
|---|---|---|---|
| 5SQ | Adjustable RF tunable inductor; verify the exact mechanical specification per model | 0.0275–0.53 µH family range | Not stated for the family in the cited RFMW description |
| 5SQSMD | SMD RF tunable coil | 28.5–465 nH | 5.9 × 6.3 × 7.5 mm |
The 5SQSMD range overlaps much of the 5SQ electrical range, but the SMD package, mounting method and adjustment access can change the achievable Q, thermal behavior and production process. Do not substitute it solely because the nominal inductance appears similar.
Rank #4
- Adjustable inductor with 90 mH to 110 mH inductance range
- Q Minimum: 30
- Test Frequency: 79 KHz
- Mounting Type: Through Hole
- Measures 0.40" x 0.55" (not including pins / mounting tabs)
How to source the parts through RFMW
- Start with the exact manufacturer designation, such as Frontier 5SQ tunable inductors or 5SQ-03A (503025-008-00).
- Open the RFMW listing and confirm the exact model, revision, package and compliance information.
- Request or download the model-specific datasheet before approving a footprint or tuning procedure.
- Check current availability, minimum order details and lead time directly with RFMW; those commercial values are not established here and can change.
- If you need an SMD alternative, search the Frontier 5SQSMD family and verify dimensions, pad layout and tuning-tool clearance against your board.
RFMW’s 2026 supplier showcase places Frontier in its broader passive-component portfolio for RF, telecommunications, automotive, industrial and power applications. Frontier’s catalog also covers inductors, capacitors, transformers, ferrites and custom magnetic solutions, so the 5SQ and 5SQSMD families can be evaluated alongside related magnetic parts.
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RFMW reproduces a Frontier claim of zero field failures among 50 million pieces shipped. That is a vendor-reported shipment and reliability statement, not an independently audited failure-rate study. Apply your own qualification requirements, including incoming inspection, environmental testing and end-of-line tuning checks, when the application is safety-critical or volume production is planned.
Selection checklist
- Operating frequency and bandwidth are below the selected model’s self-resonant frequency with practical margin.
- Required inductance range fits within the model’s actual adjustment limits.
- Q is specified at a frequency and test condition relevant to the design.
- Filter insertion loss, oscillator phase-noise goals or matching efficiency are met in the assembled circuit.
- Temperature drift and mechanical adjustment repeatability are acceptable.
- Package, footprint, tuning access and board clearances are compatible.
- The RFMW order code, manufacturer code and RoHS status are confirmed for the exact part.
The Bottom Line
RFMW is a practical source for Frontier’s 5SQ tunable inductors, including the 5SQ-03A, while Frontier’s 5SQSMD line provides an SMD option. Use the published family ranges to narrow the search, then design and order from the exact model-specific electrical and mechanical data.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
