• TexasTesla
    0
    Greetings , This is my first post so If I'm out of line please advise .
    I want to share some photos of a recent ebay purchase and see if you can help identify what exactly it is.
    It was custom framed and looks like it may be an early prototype for something .
    I figured it was an RF amplifier but it could also be some type of motion detector .
    It was described by the seller as an Apple motherboard :)
    Electronics have been a hobby of mine since my first visit to radioshack but I will admit microwave frequencies are way above me .
    Thanks .
    Attachments
    Board1.webp (108K)
    Board2.webp (95K)
    Board3.webp (51K)
    board4.webp (37K)
  • TexasTesla
    0
    So all the transistors are Fujitsu FLL100 .
    I assume going from the top down and left to right T1 is pre-amp ?
    Then thru a Wilkinson power divider into T2 and T3 Doherty power amplifier circuit (A)
    and matching power circuit (B) composed of T4 and T5 .
    Balance circuit between the two and feed into another power divider .
    Most likely a high power motion detector ?
  • TexasTesla
    0
    Ok, T1 at top could be the output section of the motion detector ?
    Remote long range guidance for amateur rocket ?
  • TexasTesla
    0
    bx00fcn1u732h80g.jpg
    ut5ahgdh1nmunbgu.jpg
    9nxj8bggrpbh69v7.jpg
    o9qcmycc9rlhw7dl.jpeg
    Attachment
    Board1 (108K)
  • UnknownEditor
    4
    That is an interesting board! I found an article where those transistors were used at L-band to make power amplifiers

    https://cds.cern.ch/record/180485/files/CM-P00059135.pdf
  • UnknownEditor
    4
    Not sure why it would be a Doherty amplifier, it looks like a simple two-stage power amp to me. Two FETs driving four FETs. Could the input and output be through the board? Maybe send a photo of the board flipped over?
  • TexasTesla
    0
    Thanks for the reply . I partially removed the board from the frame hoping to find a note / schematic or any information but none was found . No easy way to flip the board over as it's attached to foam backing
    and was professionally framed . I would hate to damage it .
    Someone cared a great deal about it . Sad it was probably dumped in a estate sale and forgotten .
  • rfdave
    0
    I think that's a nice piece of wall art. Connected to a patent of some sort possibly?
  • TexasTesla
    0
    What if a carrier frequency came in from the bottom. Then the signal splits to two transmitter circuits. They are tuned and with the doppler effect would cancel each other out at times. Movement would create a differential "tone" that is combined and transmitted by the top transistor.
  • madengr
    1
    It’s just a standard PA.
  • remlar ralmer
    0
    Let's consider a scenario where a carrier frequency enters the system from the bottom. Upon entering, the signal is divided and directed into two separate transmitter circuits. Each of these circuits is finely tuned to handle the signal, and due to the Doppler effect, there may be times when the signals from these two circuits cancel each other out. This cancellation occurs because the Doppler effect alters the frequency of the signals based on their relative motion, leading to a phase difference that can result in destructive interference.

    As movement occurs, it creates a differential frequency shift between the two signals. This frequency shift manifests as a "tone" that is essentially the difference between the frequencies of the two signals. The system is designed to capture this differential tone, which reflects the relative movement and changes in the Doppler shift. This differential tone is then combined and transmitted through the top transistor.

    The top transistor acts as the final stage of the system, taking the combined signal and transmitting it. This configuration ensures that the system is sensitive to movement and frequency changes, effectively utilizing the Doppler effect to detect and process dynamic changes in the signal. The overall design enables precise detection and measurement of movement through the differential tone produced by the interaction of the signals from the two transmitter circuits. <a href="https://boiseconcretecontractor.com/">Boise Concrete Contractor</a>
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