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  1. #1
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    Power meter in end of transmitter

    Hi

    I'm trying to make a RF circuit based on two si4713 (fm radio transmitter) that is combined into one signal, that signal is then amplified through a 7W amplifier. I have tested this circuit and it works. However I would like to measure the output power from the amplifier and build a variable gain preamp, so that I will be able to regulate the output power 1-7W from a microcontroller. Can anyone recommend a way to do this?

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    7W : https://www.ebay.co.uk/itm/7W-65MHz-...oAAOSwPWxbJ-go

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  2. #2
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    Re: Power meter in end of transmitter

    A directional coupler or SWR bridge is the preferred method to measure forward and reflected power.



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  3. #3
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    Re: Power meter in end of transmitter

    Don't use Variable Gain Amplifier, instead use a Programmable Attenuator.( There are tons of such attenuators in the market..)Because VGA will disturb the signal with its own nonlinearity.
    Also, use a Directional Coupler OR a RF Power Detector IC ( look at Analog Devices or similar mfg.) to measure accurately the RF Power then you can control RF Power by adjusting Programmable RF Attenuator


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  4. #4
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    Re: Power meter in end of transmitter

    That made a lot of sense :) Thank you for leading me in that direction



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