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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi KST24MTF

Name: KST24MTF
Brand: onsemi
SKU: KST24MTF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: KST24MTF

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: KST24MTF.pdf

Description:: TRANS NPN 30V 0.1A SOT-23-3

Quantity:: RFQ Add To RFQ list

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Inventory:9,246

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Product details

Overview

KST24MTF from ON Semiconductor (formerly Fairchild) is an NPN epitaxial silicon RF transistor optimized for VHF mixer and oscillator applications, with f_T = 400–620 MHz, V_CEO = 30 V, I_C = 100 mA, and SOT-23 package - used in FM/TV tuners and signal conversion stages.

For engineers reviewing the KST24MTF datasheet, pinout, applications, or equivalent options, key selection criteria include its verified VHF small-signal gain (24 dB at 213→45 MHz injection), low output capacitance (0.25–0.36 pF), and thermal resistance (357 °C/W) for stable RF front-end operation.

Technical Context

The KST24MTF operates as a high-frequency active device in heterodyne architectures, where its f_T > 400 MHz and low Cob enable effective frequency translation between VHF bands. Its h_FE ≥ 30 at V_CE = 10 V, I_C = 8 mA supports reliable bias stability in low-power oscillator cores.

Designed for injection-locked mixing, the KST24MTF delivers 19–29 dB conversion gain under defined conditions: I_C = 8 mA, V_CC = 20 V, oscillator injection = 150 mV, and dual test frequencies (60 MHz → 45 MHz and 213 MHz → 45 MHz).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - maximum safe collector-emitter voltage before breakdown in common-emitter configuration
f_T	400–620 MHz - usable frequency limit for unity-current-gain operation, enabling VHF signal processing
C_ob	0.25–0.36 pF - low output capacitance minimizes loading on tuned tank circuits in oscillator/mixer tanks
h_FE	≥30 at V_CE=10 V, I_C=8 mA - sufficient DC current gain for stable biasing in low-current RF stages
R_TH(j-a)	357 °C/W - thermal resistance indicates need for board-level copper pour or airflow in continuous 350 mW operation
G_G	19–29 dB - measured conversion gain across two injection test points, confirming suitability for fixed-frequency VHF downconversion

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; 3-pin configuration, JEDEC TO-236AB compliant, footprint compatible with automated placement.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased junction; requires external bias network for proper Q-point setting in mixer/oscillator use
2	Emitter	Current sink node; typically grounded or AC-coupled to reference in common-base or common-emitter RF configurations
3	Collector	Output node carrying amplified/mixed RF signal; connected to tuned load or coupling capacitor in VHF stage

Key Features

Feature	Design Value
VHF-optimized f_T	Guaranteed minimum 400 MHz enables reliable operation up to 213 MHz input signals without gain collapse
Low C_ob	0.25–0.36 pF reduces parasitic loading on resonant circuits, preserving Q-factor in LC tank designs
High conversion gain	19–29 dB measured under standardized 150 mV injection confirms strong nonlinearity for efficient mixing
SOT-23 footprint	Standardized 3-pin package allows drop-in replacement in space-constrained tuner modules and portable receivers

Applications

FM Radio Tuner Front-End	TV Channel Selector Oscillator
Use Scenario: Selecting and downconverting FM broadcast band (88–108 MHz) signals in portable radios. IC Role / Device Role / Timing Role: VHF mixer transistor converting RF input to 10.7 MHz IF using local oscillator injection. Use Value: 24 dB typical conversion gain and 0.36 pF C_ob maintain SNR and selectivity in compact PCB layouts.	Use Scenario: Generating stable local oscillator signals for UHF/VHF TV channel selection in analog TV tuners. IC Role / Device Role / Timing Role: Self-oscillating active device in Colpitts or Hartley topology, leveraging f_T > 400 MHz. Use Value: Verified 29 dB gain at 60→45 MHz injection supports robust oscillation margin and low phase noise.
Wireless Microphone Receiver	VHF Surveillance Transceiver
Use Scenario: Demodulating VHF-band audio transmissions (174–216 MHz) in professional wireless mic systems. IC Role / Device Role / Timing Role: First-stage mixer translating received VHF carrier to low-IF for analog demodulation. Use Value: Low 50 nA I_CBO ensures minimal drift over temperature, critical for consistent audio fidelity.	Use Scenario: Bidirectional signal translation in compact VHF surveillance equipment operating near 144–148 MHz. IC Role / Device Role / Timing Role: Shared-function transistor used alternately as oscillator and mixer in half-duplex architecture. Use Value: Matched V_CEO = 30 V and P_C = 350 mW rating support both transmit drive and receive sensitivity requirements.

FM Radio Tuner Front-End

TV Channel Selector Oscillator

Use Scenario: Selecting and downconverting FM broadcast band (88–108 MHz) signals in portable radios.

IC Role / Device Role / Timing Role: VHF mixer transistor converting RF input to 10.7 MHz IF using local oscillator injection.

Use Value: 24 dB typical conversion gain and 0.36 pF C_ob maintain SNR and selectivity in compact PCB layouts.

Use Scenario: Generating stable local oscillator signals for UHF/VHF TV channel selection in analog TV tuners.

IC Role / Device Role / Timing Role: Self-oscillating active device in Colpitts or Hartley topology, leveraging f_T > 400 MHz.

Use Value: Verified 29 dB gain at 60→45 MHz injection supports robust oscillation margin and low phase noise.

Wireless Microphone Receiver

VHF Surveillance Transceiver

Use Scenario: Demodulating VHF-band audio transmissions (174–216 MHz) in professional wireless mic systems.

IC Role / Device Role / Timing Role: First-stage mixer translating received VHF carrier to low-IF for analog demodulation.

Use Value: Low 50 nA I_CBO ensures minimal drift over temperature, critical for consistent audio fidelity.

Use Scenario: Bidirectional signal translation in compact VHF surveillance equipment operating near 144–148 MHz.

IC Role / Device Role / Timing Role: Shared-function transistor used alternately as oscillator and mixer in half-duplex architecture.

Use Value: Matched V_CEO = 30 V and P_C = 350 mW rating support both transmit drive and receive sensitivity requirements.

Equivalent & Alternatives

The following parts are listed as comparable options for similar VHF mixer transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MPSH10-RT1	f_T = 650 MHz (higher), V_CEO = 25 V (lower), C_ob = 0.4 pF (higher)	Better high-frequency gain but reduced voltage headroom limits use in 20 V oscillator supplies	Prefer when f_T margin > 50 MHz is required and supply ≤ 20 V
2SC3356-GR	f_T = 7 GHz (much higher), V_CEO = 12 V, SOT-23-3 package	Overqualified for VHF; excessive f_T increases layout sensitivity and cost without benefit	Select only if future UHF extension is planned and 12 V supply is guaranteed

Compared with MPSH10-RT1 and 2SC3356-GR, the KST24MTF offers optimal balance of VHF gain, voltage rating, and thermal performance for legacy tuner designs - avoiding overdesign while ensuring compatibility with 20 V oscillator rails and standard SOT-23 footprints.

Availability

KST24MTF is available at Aetrix Electronics and suitable for FM radio tuners, analog TV channel selectors, wireless microphone receivers, and VHF surveillance transceivers requiring stable component supply and long-lifecycle support.

Supply support for KST24MTF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

ON Semiconductor is a global semiconductor supplier delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud computing, and consumer electronics.

The KST24MTF belongs to Fairchild's legacy RF transistor family, designed specifically for VHF signal conversion in analog broadcast receiver front-ends and low-power oscillator circuits.

FAQ

What is the maximum collector-emitter voltage rating for KST24MTF?

The KST24MTF has a maximum collector-emitter voltage (V_CEO) rating of 30 V at T_A = 25 °C. This rating defines the upper limit for safe DC or peak AC voltage applied between collector and emitter with base open. Exceeding 30 V risks avalanche breakdown and permanent damage. The KST24MTF must be operated within this limit in all applications, including FM tuner oscillators and VHF mixers.

Does KST24MTF support operation at 213 MHz input frequency?

Yes, the KST24MTF is characterized for 213 MHz to 45 MHz conversion gain (24 dB typical) under specified test conditions: I_C = 8 mA, V_CC = 20 V, and 150 mV oscillator injection. Its f_T range of 400–620 MHz confirms usable gain at 213 MHz, making it suitable for VHF band mixing in TV tuners and surveillance receivers where KST24MTF serves as the active mixing element.

What is the thermal resistance junction-to-ambient for KST24MTF?

The KST24MTF has a thermal resistance junction-to-ambient (R_TH(j-a)) of 357 °C/W under standard SOT-23 mounting conditions on FR-4 PCB with no copper pour. This value implies that at full 350 mW power dissipation, junction temperature rise exceeds 125 °C above ambient - requiring careful thermal design. For reliable long-term operation, the KST24MTF should be used below 200 mW or with enhanced board-level heat sinking.

Is KST24MTF pin-compatible with other SOT-23 NPN transistors?

The KST24MTF uses standard SOT-23 pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. It is mechanically pin-compatible with most 3-pin SOT-23 NPN transistors, but electrical compatibility depends on parameters like f_T, V_CEO, and h_FE. Substituting another part requires verifying those specs - for example, the KST24MTF's 30 V V_CEO and 400–620 MHz f_T are not matched by generic switching transistors.

What is the typical output capacitance (C_ob) of KST24MTF?

The KST24MTF has a typical output capacitance (C_ob) of 0.36 pF, measured at V_CB = 10 V, I_E = 0, and f = 1 MHz. This low value helps preserve Q-factor in VHF tank circuits and reduces unwanted coupling in mixer/oscillator stages. The guaranteed range is 0.25–0.36 pF, and designers should use the max value (0.36 pF) for worst-case impedance matching when laying out circuits with KST24MTF.

KST24MTF Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: -

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 30 @ 8mA, 10V

Power - Max:: 350 mW

Frequency - Transition:: 620MHz

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

KST24MTF FAQ

1.How can I place an order for KST24MTF through Aetrix?

Please submit a Request for Quotation (RFQ) for KST24MTF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for KST24MTF reliable?

The price and inventory of KST24MTF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for KST24MTF is usually 5 days.

3.What payment methods are accepted for KST24MTF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for KST24MTF transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for KST24MTF?

KST24MTF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your KST24MTF order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for KST24MTF?

For technical support, including KST24MTF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your KST24MTF requirements.

6.How does Aetrix verify that KST24MTF is sourced from the original manufacturer or authorized distributors?

All KST24MTF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that KST24MTF meets industry standards.

7.What is the process for return or replacement of KST24MTF?

All KST24MTF units undergo pre-shipment inspection (PSI). If there is an issue with KST24MTF, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The KST24MTF part is unused and in its original packaging.

Return procedure for KST24MTF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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