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  • High frequency amplifier

    Good day,
    Can anyone help me with a schematic diagram of a 50-100W power amplifier with semiconductors that works from about 100kHz to 3-4MHz?
    Also I'am interested in methods of producing High Frequency oscillations other than Tesla electro-mechanical oscillators and Trichel Pulse Triode. I'am interested in high power installations to produce HF oscillations.

    Thank you,
    Last edited by Buddhafollower; 11-23-2018, 10:21 AM.

  • #2
    Originally posted by Buddhafollower View Post
    Good day,
    Can anyone help me with a schematic diagram of a 50-100W power amplifier with semiconductors that works from about 100kHz to 3-4MHz?
    Also I'am interested in methods of producing High Frequency oscillations other than Tesla electro-mechanical oscillators and Trichel Pulse Triode. I'am interested in high power installations to produce HF oscillations.

    Thank you,
    Unless you are a licensed Amateur Radio Operator, producing that much power at those frequencies is illegal unless you have very strong shielding that would prevent any radiation of power. And in most countries you will have the authorities knocking on your door pretty quickly for sending out a signal in that frequency range.


    Respectfully,
    Carroll
    Just because someone disagrees with you does NOT make them your enemy. We can disagree without attacking someone. This means YOU especially BroMikey.

    Comment


    • #3
      I know, i know but this is for something else than transmitting hertzian waves. So please, if you have such a schematic do share with me.

      Thank you

      Comment


      • #4
        Try the WEB

        https://www.google.se/search?q=100w+...QzBRS6Wl3UkqM:

        Comment


        • #5
          Unfortunately the above amplifier works from 50-52MHz. Far more than what i require.
          Thank you anyway.

          Comment


          • #6
            https://www.google.se/search?tbm=isc...Hppr_0QndiMHM:

            https://www.qsl.net/va3iul/Homebrew_..._Amplifier.gif

            Regards Arne

            Comment


            • #7
              the big issue with most RF amps is the filtering.
              clearly the electricity does not stick inside the wires very well when you get up to HF frequencies, so it is super easy for the input of a section to get noise from the output (creating unwanted oscillation).
              so the 2 things that really help with that is to always have an amplifier that inverts the output for your final high power stage (often this is just an issue of correct wiring on a matching transformer)

              and the other big thing to do is to put a low pass filter on the output stage so that high frequencies out of range don't show up (this can fry an amp fairly fast, and the unwanted harmonics out will get you noticed and caught way faster even if it does not hurt the amplifier)

              and the other thing that would likely be a good idea, but not needed if you are careful, is to set up a circuit that watches output power, this signal is then sent back to your HF generator to limit the power into the amplifier. this keeps your waveform clean and keeps things from spiraling out of control and frying your amplifier. This idea is called ALC by radio people.

              other thoughts,
              it might be easier for you to just buy an amplifier,
              they are not that pricy anymore.
              here is a place that sells pretty low priced ones
              Amplifier
              but I would not push any of them more than 1/3 of the limit they claim to have. (I say this because I know others that have melted them.

              more other thoughts.
              whatever you are putting the radio waves into,
              the idea of SWR is something you are going to need to know if you are not to fry your amplifier no matter what kind you get
              https://en.wikipedia.org/wiki/Standing_wave_ratio

              one last thing.
              might be easier to just get a standard radio transceiver and antenna tuner that work on the frequency range you want.
              many standard transceiver and antenna tuners deal with 100W out no problem, no additional amplifier needed either.
              only time that will not work is if you are requiring a specific wave shape out. and in that case, maybe you are better off building some of it.

              Comment


              • #8
                Thank you very much for your advices, sir.

                Comment


                • #9
                  Apex

                  Apex op Amps are impressive

                  https://www.apexanalog.com/products/pa107.html

                  Comment


                  • #10
                    Originally posted by aniccame View Post
                    yes they are, and at $321.10 each they should be.
                    https://www.digikey.com/products/en/...ps/687?k=pa107

                    Comment


                    • #11
                      Good day,
                      In this link is a power amplifier with Mosfet IRFP150. At the end the man shows us the installation and it has a combiner. Please tell me how to construct this combiner.
                      https://www.youtube.com/watch?v=BfbMSnttBTI
                      This is the schematic:
                      Schematic 300w Rf Amplifier Usin
                      That four to one ratio of L5 i really don't get...

                      Comment


                      • #12
                        This video which i found kinds says it all.
                        https://www.youtube.com/watch?v=32R9IcFf7fc
                        So the secondaries of T4 (in the picture it says L4) consist of four turns of multi stranded copper wire while the combiner is only 2 turns, one in each side and with a center tap. Nice

                        Comment


                        • #13
                          so you answered all your questions yourself ?

                          Comment


                          • #14
                            i guess so, yeah

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