2N4427 RF Transistor NPN Equivalent & Substitute Parts

Part Overview

The 2N4427 is an RF transistor NPN manufactured by Central Semiconductor Corp, designed for RF applications operating at 500MHz with a maximum power rating of 1W. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and production continuity. The 2N4427 features a through-hole TO-39 metal can package and operates across a wide temperature range from -65°C to 200°C.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	-
Voltage - Collector Emitter Breakdown (Max)	20	V
Frequency - Transition	500	MHz
Gain	10	dB
Power - Max	1	W
DC Current Gain (hFE) (Min) @ Ic, Vce	10 @ 100mA, 5V	-
Current - Collector (Ic) (Max)	400	mA
Operating Temperature	-65 to 200	°C (TJ)
Mounting Type	Through Hole	-
Package / Case	TO-205AD, TO-39-3 Metal Can	-
Product Status	Obsolete	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution of the 2N4427 is determined by the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (mandatory match)
Voltage - Collector Emitter Breakdown (Max): Must equal or exceed 20V for direct replacement
Frequency - Transition: Must support 500MHz minimum operation
Power - Max: Must support 1W or higher dissipation
Current - Collector (Ic) (Max): Must support 400mA or higher
DC Current Gain (hFE): Minimum 10 at specified operating conditions

Secondary Considerations:

Mounting Type: Through Hole preferred for legacy board compatibility; Surface Mount substitutes require PCB redesign
Package compatibility: TO-39 metal can is the original form factor
Operating Temperature Range: Must support -65°C to 200°C or equivalent industrial range
RoHS and REACH Compliance: All substitutes must maintain ROHS3 compliance

The substitute parts listed below are manufacturer-recommended alternatives that meet or exceed the electrical specifications of the 2N4427. However, substitutes with higher frequency ratings, lower voltage ratings, or surface-mount packages represent design upgrades rather than direct pin-compatible replacements.

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Voltage - Collector Emitter Breakdown (Max) [V]	Frequency - Transition [MHz/GHz]	Gain [dB]	Power - Max [mW/W]	Ic (Max) [mA]	hFE (Min)	Mounting Type	Package / Case	Product Status
2N4427	Central Semiconductor Corp	NPN	20	500 MHz	10	1 W	400	10	Through Hole	TO-39-3 Metal Can	Obsolete
2SC5226A-5-TL-E	onsemi	NPN	10	7 GHz	12	150 mW	70	135	Surface Mount	SC-70, SOT-323	Active
BF771E6327HTSA1	Infineon Technologies	NPN	12	8 GHz	10-15	580 mW	80	70	Surface Mount	SOT-23-3	Active
BFP196WNH6327XTSA1	Infineon Technologies	NPN	12	7.5 GHz	9.7	700 mW	150	70	Surface Mount	SOT-343	Active
BFP450H6327XTSA1	Infineon Technologies	NPN	5	24 GHz	15.5	450 mW	100	60	Surface Mount	SOT-343	Active
BFP520H6327XTSA1	Infineon Technologies	NPN	3.5	45 GHz	22.5	100 mW	40	70	Surface Mount	SOT-343	Active
BFP620H7764XTSA1	Infineon Technologies	NPN	2.8	65 GHz	21.5	185 mW	80	110	Surface Mount	SOT-343	Active
BFP650H6327XTSA1	Infineon Technologies	NPN	4.5	37 GHz	10.5-21.5	500 mW	150	110	Surface Mount	SOT-343	Active
BFP720H6327XTSA1	Infineon Technologies	NPN	4.7	45 GHz	10.5-28.5	100 mW	25	160	Surface Mount	SOT-343	Active
BFP842ESDH6327XTSA1	Infineon Technologies	NPN	3.7	60 GHz	26	120 mW	40	150	Surface Mount	SOT-343	Active
BFR380FH6327XTSA1	Infineon Technologies	NPN	9	14 GHz	9.5-13.5	380 mW	80	90	Surface Mount	SOT-723	Active

Engineering Selection Recommendations

For Direct Through-Hole Replacement:

No active through-hole RF transistor NPN substitute is available that maintains the TO-39 metal can package form factor. The 2N4427 is obsolete and all manufacturer-recommended substitutes employ surface-mount technology (SOT-23-3, SOT-343, SOT-723 packages). Direct board-level replacement without PCB redesign is not feasible.

For Surface-Mount Design Migration:

When transitioning to surface-mount technology, the following substitutes are recommended based on voltage and frequency requirements:

BFR380FH6327XTSA1 (Infineon Technologies): Operates at 9V maximum collector-emitter breakdown voltage and 14GHz transition frequency. Suitable for applications requiring moderate voltage headroom and GHz-range RF performance. Provides 380mW power dissipation and 80mA maximum collector current. Active product status with ROHS3 compliance.
BFP196WNH6327XTSA1 (Infineon Technologies): Operates at 12V maximum collector-emitter breakdown voltage and 7.5GHz transition frequency. Offers 700mW power dissipation and 150mA maximum collector current, providing higher power handling than BFR380. Active product status with ROHS3 compliance.
BF771E6327HTSA1 (Infineon Technologies): Operates at 12V maximum collector-emitter breakdown voltage and 8GHz transition frequency. Provides 580mW power dissipation and 80mA maximum collector current. Active product status with ROHS3 compliance.

Compliance Status:

All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, matching the regulatory requirements of the 2N4427. All substitutes operate at maximum junction temperatures of 150°C, which is lower than the 2N4427 specification of 200°C. Thermal design review is required for applications operating above 150°C.

Frequently Asked Questions (FAQ)

Q1: Can the 2N4427 be replaced with a direct pin-compatible through-hole substitute?

A: No. The 2N4427 is obsolete and all manufacturer-recommended substitutes are surface-mount devices. Direct board-level replacement requires PCB redesign to accommodate surface-mount packages such as SOT-23-3, SOT-343, or SOT-723.

Q2: What is the primary difference between the 2N4427 and the recommended substitutes?

A: The 2N4427 is a through-hole TO-39 metal can device rated for 500MHz operation at 1W power dissipation. Substitutes are surface-mount RF transistors with significantly higher frequency ratings (7GHz to 65GHz) and lower power dissipation (100mW to 700mW). Substitutes are designed for modern RF and microwave applications requiring higher frequency performance.

Q3: Which substitute is most suitable for legacy 500MHz RF applications?

A: BFR380FH6327XTSA1 (14GHz) or BF771E6327HTSA1 (8GHz) are appropriate for 500MHz applications, as both exceed the frequency requirement and provide adequate voltage ratings (9V and 12V respectively). However, PCB redesign is mandatory due to package incompatibility.

Q4: Are all substitutes RoHS compliant?

A: Yes. All listed substitutes are ROHS3 compliant and REACH unaffected, matching the regulatory status of the 2N4427.

Q5: What is the maximum operating temperature for substitutes compared to the 2N4427?

A: The 2N4427 operates from -65°C to 200°C (TJ). All listed substitutes operate from -65°C to 150°C (TJ). Applications requiring operation above 150°C require thermal management review or alternative component selection.

Q6: Can substitutes with lower voltage ratings (3.5V to 5V) replace the 2N4427 (20V)?

A: No. Substitutes with lower voltage ratings (BFP520H6327XTSA1 at 3.5V, BFP450H6327XTSA1 at 5V, BFP620H7764XTSA1 at 2.8V) are not suitable for applications requiring 20V collector-emitter breakdown voltage. These devices are designed for low-voltage RF and microwave applications and will fail if subjected to 20V bias conditions.

Q7: What packaging considerations apply when selecting a substitute?

A: All substitutes employ surface-mount packages (SOT-23-3, SOT-343, SOT-723). PCB layout, trace impedance, and thermal management differ significantly from through-hole TO-39 designs. Prototype testing and RF characterization are required to validate performance in the target application circuit.

Q8: Which substitute provides the closest electrical match to the 2N4427?

A: BFR380FH6327XTSA1 provides moderate frequency capability (14GHz) with 9V voltage rating and 380mW power dissipation, representing a reasonable compromise for legacy RF applications. However, no substitute exactly matches the 2N4427 specifications due to technology evolution toward higher frequency, lower power surface-mount devices.

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