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BD400 transistor equivalent.

Discussion in 'Radio and Wireless' started by vari21, Apr 15, 2020.

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  1. vari21

    vari21

    10
    0
    Apr 15, 2020
    hello everyone.
    im looking for the right equivalent of bd400 transistor

    BD400, SILICON, NPN, TRANSISTOR.
    Type Designator: BD400
    Material of Transistor: Si
    Polarity: NPN
    Maximum Collector Power Dissipation (Pc): 15 W
    Maximum Collector-Base Voltage |Vcb|: 170 V
    Maximum Collector-Emitter Voltage |Vce|: 100 V
    Maximum Emitter-Base Voltage |Veb|: 7 V
    Maximum Collector Current |Ic max|: 1 A
    Max. Operating Junction Temperature (Tj): 150 °C
    Transition Frequency (ft): 0.5 MHz
    Forward Current Transfer Ratio (hFE), MIN: 40
    Package: TO126
    i ve uploaded a picture of the transistor, and the shematics.the BD400 transistor in the shematics isT104 just to show were it is located.
    i appreciate any help thanks.
     

    Attached Files:

  2. bertus

    bertus Moderator

    744
    263
    Nov 8, 2019
    Hello,

    It is weird that a BD400 with an Ft of only 0.5 MHz is used in a 27 MHz transmitter.
    For that posistion you would need a transistor with a Ft of at least 100 MHz, to have any effect.

    Bertus
     
  3. vari21

    vari21

    10
    0
    Apr 15, 2020
  4. bertus

    bertus Moderator

    744
    263
    Nov 8, 2019
    Hello,

    I would expect a HF transistor on that position, rather than a power transistor.
    The 2N3866, 2N3553 or BFY50 come in mind.

    Bertus
     

    Attached Files:

  5. vari21

    vari21

    10
    0
    Apr 15, 2020
    thanks for your recommandations bertus ,anyway when i opened the transmiter i found that transistor bd400 located t104 and it seems it s the original from factory.i think it s a power transistor because it is connected to the battery terminal through dr101 and c103.
     
  6. bertus

    bertus Moderator

    744
    263
    Nov 8, 2019
    Hello,

    It is also strange that in the pulse part of the schematic, the transistor types are given, but not in the RF part.
    Where did you find the schematic?
    Was it on a website?
    Perhaps there is more info over there.

    Bertus
     
  7. vari21

    vari21

    10
    0
    Apr 15, 2020
    the shematics can be found online just type varioprop12s on google.i ve uploaded another shematics not in english but in german i think it s the original one.
     

    Attached Files:

    • 12s.jpg
      12s.jpg
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  8. bertus

    bertus Moderator

    744
    263
    Nov 8, 2019
  9. vari21

    vari21

    10
    0
    Apr 15, 2020
    hi bertus ,yes this radio is 1.3w it is powered with 12v battery i think
     
  10. bertus

    bertus Moderator

    744
    263
    Nov 8, 2019
    Hello,

    The 2N3866 will be capable of about 1 Watt.
    The 2N4427 (mentioned in the 2N3866 datasheet) will work better on 12 Volts and also be capable of about 1 Watt.
    The 2N3553 will be capable of about 3 Watt.

    Bertus
     
  11. vari21

    vari21

    10
    0
    Apr 15, 2020
    hello bertus,
    which one of the given 3 transistors do you think will work on my radio i will order it right now.
    buy the way i ve got in my box the 2N2219 what do you think about it?
     
  12. bertus

    bertus Moderator

    744
    263
    Nov 8, 2019
    Hello,

    The 2N2219 has only a max power of 800 mW.
    Using it as amplifier it will likely put out about 400 mW max.

    Bertus
     

    Attached Files:

  13. aurelZ

    aurelZ

    77
    9
    Jun 10, 2019
    It is weird that a BD400 with an Ft of only 0.5 MHz is used in a 27 MHz transmitter.
    For that posistion you would need a transistor with a Ft of at least 100 MHz, to have any effect.

    agreed ..this must be some kind of FAKE...
    If you can find old crt tv use transistors from chrome amplifiers even are lower freq some of them work up to 150Mhz
    and on 12 V power you can build solid RF amp.
     
    bertus likes this.
  14. vari21

    vari21

    10
    0
    Apr 15, 2020
    hi bertus ,so do you think the 2N3553 will do the job since it s 3w ,or the 2N3866 is much better
    please could you confirm thanks.
     
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