Mystery Ebay purchase
  • 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 Options
  • 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 Options
  • TexasTesla
    0
    Ok, T1 at top could be the output section of the motion detector ?
    Remote long range guidance for amateur rocket ?
    TexasTesla Options
  • TexasTesla
    0
    bx00fcn1u732h80g.jpg
    ut5ahgdh1nmunbgu.jpg
    9nxj8bggrpbh69v7.jpg
    o9qcmycc9rlhw7dl.jpeg
    Attachment
    Board1 (108K)
    TexasTesla Options
  • 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 Options
  • 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?
    UnknownEditor Options
  • 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 .
    TexasTesla Options
  • rfdave
    0
    I think that's a nice piece of wall art. Connected to a patent of some sort possibly?
    rfdave Options
  • 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.
    TexasTesla Options
  • madengr
    1
    ↪TexasTesla
    It’s just a standard PA.
    madengr Options
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