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Mismatch&power leakage with port of mixersattenuators solution

  1. May 23, 2013 #1
    Hi ! I am making an RF Transmitter and i have a problem with power leakage for LO port to IF port and RF port. I don't know what to do and i am little confused about how can i fix this.

    Source(-10 or -20dBm) 10KHz --------->MIxer conv.loss=8db--------->RF port


    L.O=70MHz and 7dbm

    I put an oscilloscope to mixers input IF and i don't see a sin wave from my Source. I is a sine wave with a lot of phase noice and amplitude variations..when i decrease the L.O power the sine becomes better.:eek:

    I have heard about attenuators but i cannot understand how they will solve the problem. They attenuate maybe the standing waves that maybe create ?Also and my signal right?
    I don't understand...
  2. jcsd
  3. May 23, 2013 #2


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    Staff: Mentor

    Can you post a schematic and some photos? What bands are you building this transmitter for?
  4. May 23, 2013 #3
    P5181092_zps5ee33fa8.jpg "] P5181092_zps5ee33fa8.jpg [/URL]of course...here...i have some problem with the crystal filter there..but basically this is my transmitter...i think i will need attenuators sure before the mixers....
  5. May 23, 2013 #4


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    Science Advisor
    Gold Member
    2017 Award

    just a little note on circuit symbols....

    are they supposed to be band pass filters ??

    if so you need to learn to draw them correctly, the centre sine wave shouldnt have a strike through it ;)
    as you have shown them they let nothing through low mid or hi

  6. May 24, 2013 #5
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