need some help to know facts about rf transistor designing

Discussion in 'Wireless & RF Design' started by alitex, Mar 1, 2012.

  1. alitex

    Thread Starter Active Member

    Mar 5, 2007
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    hi all.
    i want to know some basic information's about designing multistage rf transistor amplifier...
    in the beginning i made 3 stage transistor(2n3904,2n3904,2n2222) 27 MHz class a amplifier, am modulation (vcc 12V),
    _i amplified the rf signal from 50 mV to 400 mV,is this value good or bad?

    _how is the best value of signal voltage in the 3 stage can i arrived to it?

    i have transistor (2n3553) can i use it as class a transistor or power transistor?

    in the power transistor, how i can calculate the RFC value that connected between vcc and collector?

    i based in test on test board, is this true or false?

    i think i'm heavy, but really very need to know this information's...

    thank's in advance
     
  2. bertus

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    Apr 5, 2008
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  3. alitex

    Thread Starter Active Member

    Mar 5, 2007
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    thank you Mr bertus, really very important informations in pdf file.
    i want to ask how to know what is the value of input signal voltage or power of input signal must applied to the circuit in the 2n3553 datasheet?
    it give 2.5 Watt output signal...
     
  4. bertus

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  5. alitex

    Thread Starter Active Member

    Mar 5, 2007
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    thank u Mr bertus...
    i have another question please.
    how i calculate input impedance for 2n3553 or 2sc2336 at 27 MHz(class e power amplifier) because there is no characteristic for input impedance in the datasheet,as you know i must make matching network..
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    When you look at the datasheet, the power output graphs go down to 50 Mhz.
    I assume the circuit will become instable below the 50 Mhz.

    The use of VHF transistors is not recommeded for use at HF.
    For 27 Mhz there will be other transistors available like the 2sc5739, mrf449.

    This page from Advance Semiconductors might give you some more info:
    http://www.advancedsemiconductor.com/transistors/rf_power_transistors.html

    The pdf's on this search page might also be of any help:
    http://www.ufgop.org/pdf/hf-amplifier-design/

    Bertus
     
    Last edited: Mar 7, 2012
  7. alitex

    Thread Starter Active Member

    Mar 5, 2007
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    Thank you bertus
     
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