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    Circuit to detect presence of a single RF frequency ?

    Hi.
    -Detection here not meaning to demodulate-
    Detection as to know if 10.7MHz ± 100KHz is present on an existing receiver circuit node, to turn a LED on. How should be done ? Any dedicated IC or portion of such that does/could do it ?
    Abolish the deciBel !

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    Re: Circuit to detect presence of a single RF frequency ?

    A simple amplifier then a ceramic 10.7MHz filter following a amplifier+comparator will turn-on the LED.
    Even an OPAMP may work with a appropriate circuit combination.There are many choices..



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    Re: Circuit to detect presence of a single RF frequency ?

    I don't know how can a LED turn on with such a high frequency, I think a mixer + 10MHz oscillator + low-pass filter + amplifier rather capable.
    SA612 could be good because it contains mixer and oscillator.
    "Try SCE to AUX." /John Aaron/



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    Re: Circuit to detect presence of a single RF frequency ?

    Use a PLL and connect the LED to the lock indicator. By changing the VCO components you can set the center frequency and by changing the loop components you can set the lock bandwidth.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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    Re: Circuit to detect presence of a single RF frequency ?

    HMC1120 from analog can do the work. It is may be over-qualified.
    https://www.analog.com/media/en/tech...ts/hmc1120.pdf

    You may need to put a bandpass filter to just detect the 10.7MHz signal.



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    Re: Circuit to detect presence of a single RF frequency ?

    Quote Originally Posted by BigBoss View Post
    A simple amplifier then a ceramic 10.7MHz filter following a amplifier+comparator will turn-on the LED.
    Even an OPAMP may work with a appropriate circuit combination.There are many choices..
    i would modify this...ceramic filter, amplifier with 15 db gain at 10.7 MHz, another ceramic filter, then a schottky diode detector. The DC output of the detector can drive a comparator with a TTL output, that you could add a resistor limited LED to.

    by using TWO ceramic filters...you can get almost 60 dB rejection of other frequencies.



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