Input/Output Voltage Class C RF Amp

Discussion in 'The Projects Forum' started by dccircuit, Dec 16, 2015.

  1. dccircuit

    Thread Starter New Member

    Aug 3, 2014
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    0
    Hi all:

    I am a new member here with my first post. I am an adult learner trying to self-teach RF electronics. I have been working through David Rutledge's Electronics of Radio, while building the NorCal 40A transceiver.
    I am getting caught up on understanding the Class C RF power amplifier circuit.

    I don't understand how the output voltage across the collector of Q7 can be more than twice the DC supply voltage (12VDC). I assume that the reactive components--such as RFC1--are storing energy?

    [​IMG]
    Any help would be appreciated. I have included the schematic.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    Actually, the PI net on the output, C45, L7,... RFC1 is specifically chosen not to store energy...
     
  3. dccircuit

    Thread Starter New Member

    Aug 3, 2014
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    0
    Thanks Mike--can you explain how that is working?
     
  4. SLK001

    Well-Known Member

    Nov 29, 2011
    810
    224
    You could have an inphase reflection that will double the peak to peak voltage at the collector. The 43V zener diode is a last ditch effort to protect the power transistor from Vce breakdown failure. Your output capacitors also need a breakdown voltage at least 4 times the static DC voltages.

    Also, this post should be in the Radio and Communications section of the forum.
     
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