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MRF237 Transistor Data

Key transistor data for the MRF237 RF power transistor including key electrical parameters, pinout, package type and many other key transistor datasheet details.

The MRF237 is described as being designed for 12.5 volt large signal power amplifier applications in communications equipment operating up to 225 MHz.

At 12.5 volts and operating at 175MHz is is specified as providing 4 watts output with a minimum of 12dB gain and efficiency of 50%.

Key details and performance parameters for the 2N4427 transistor.

Transistor Datasheet Parameters & Data
Parameters	Details
Transistor type	NPN silicon RF power transistor
Package type	TO39
V_CBO max (V)	36
V_CEO max (V)	18
V_EBOmax (V)	4.0
I_C max (mA)	640 continuous
T_J Max °C	200
P_TOT W	8
f_T min (MHz)	500
C_OB	15pF typical 20pF max
h_fe	5 min
I_C for h_fe	250 mA
Similar / equivalents

Outline:

Pinout: see below for details

Explanation of transistor parameters

Parameter	Explanation
V_CBO Max	Maximum collector-base voltage with emitter open circuit .
V_CEO Max	Maximum collector-emitter voltage with base open circuit.
V_EBO Max	Maximum emitter-base voltage with collector open circuit.
V_CEsat (included where applicable)	The voltage drop across the collector-emitter when the transistor is fully saturated (acting as a closed switch).
I_C Max	Maximum collector current.

Parameter	Explanation
T_J	Maximum junction temperature.
P_TOT Max	Maximum device dissipation normally in free air at 25°C unless other conditions indicated.
f_T Min	Minimum cutoff frequency at which the current gain in a common emitter circuit falls to unity.
C_OB Max	Maximum collector capacitane, normally measured with emitter open circuit.
h_FE	DC current gain for H_FE at I_C. [Note hfe is the small signal gain and although this may be slightly different, the transistor current gain will vary considerably from ne transistor to the next of the same type.]
P_TOT Max	Maximum device dissipation normally in free air at 25°C unless other conditions indicated.

These are the main transistor parameters that have been included in our list. There are others, but these help quantify the main elements of the performance of the transistor.

Read more about . . . . Transistor Data-sheet Specifications & Parameters.

Please note, that the data given is the best estimate we can give within a tabulated summary of this nature. Parameters also vary between manufacturers. Electronics Notes cannot accept any responsibility for errors, inaccuracies, etc, although we do endevaour to ensure the data is as accurate as possible.

Notes and supplementary information

• Availability & sources

The device is available from a very limited number of stockists and suppliers.

• Warning

The MRF237 was primarily manufactured by Motorola, but it was second sourced by Advanced Semiconductor Inc. The parameters between transistors from the two manufacturers are very similar and this makes them ideal.

However, and this is a major issue, the pin connections different between the two manufacturers. The collector and base are reversed between the two manufacturers.

MRF237 transistor pinout differences between MoTorola and Advanced Semiconductor devices — MRF237 transistor pinout differences between Motorola and Advanced Semiconductor devices

Normally it is expected that the tab on a TO39 case coincides with the emitter, but the Motorola version of the MRF237 has the collector adjacent to the tab.

The Motorola datasheet describes the device as having a grounded emitter TO39 package for high gain excellent heat dissipation, which might explain the unusual pinout.

• Applications

The MRF237 was used in many communications systems where it was an ideal RF driver or output device for HF, VHF and UHF medium power transmitters.

It was often used in commercial equipment: everything from VHF to UHF radio transceivers and handheld devices.

It was also used in some amateur radio transceivers. One example was the TenTec Argosy HF CW/SSB transceiver.

If it is necessary to replace the MRF237 as a result of a failure, then it is necessary to be aware of the pinout changes when any replacements are sourced as Motorola devices are not always easy to purchase these days.