Can a KSP10 drive 2N3866?

Discussion in 'Wireless & RF Design' started by Willen, Apr 18, 2018.

  1. Willen

    Thread Starter Member

    Nov 13, 2015
    265
    27
    Hi,
    With the help of few kind engineers, I got some RF power transistors and smaller (in power) is 2N3866. So I have no 'medium' power RF transistor to drive 2n3866. I have 2n3904, 2n4401 but they seems bad with VHF amplifier. I have UHF transistors like S9018, 2n3663, MPSH34 but I know they are just 'signal' transistor and will not drive a powerful 2n3866.

    I have KSP10 too. When I saw Fairchild's datasheet, maybe I saw some nice parameter ratings. Then want to ask: can the KSP10 drive the 2n3866 stage (in the case of VHF/UHF amp) and imagine the 2n3866 is biased as class C amplifier.
     
    Last edited: Apr 18, 2018
  2. Hymie

    Active Member

    Mar 30, 2018
    530
    123
    The short answer to your question is yes – but looking at the data sheet for the 2N3866 the gain (hfe) can be as low as 5 where a high collector current is used (360mA). The transistor has a lower gain bandwidth (ft) of 400MHz Vs 650MHz for the KSP10 – otherwise one driving the other should be OK.
     
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  3. Willen

    Thread Starter Member

    Nov 13, 2015
    265
    27
    Does this mean 20mW input will give 100mW output?

    And maybe KSP10 pretty nice gain around 100MHz. Am I right if I said the KSP10 is pretty powerful (let's say medium power RF transistor) than S9018 or than MPSH34?
     
  4. Hymie

    Active Member

    Mar 30, 2018
    530
    123
    Electrical power is amps x volts – the gain of a transistor is the current gain.
    So if the KPS10 is delivering 70mA to the 2N3866, then it will be able to pass a collector current of 350mA (if its gain is 5).

    I suggest you study the data sheets of the transistors in question and compare their operating parameters to answer your question.
     
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