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Variable capacitor help

Discussion in 'Radio Circuits, Repair & Performance' started by WO1X, Oct 1, 2019.

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  1. WO1X

    WO1X Platinum Subscriber Platinum Subscriber QRZ Page

    I made a dumb mistake, I own a older Tokyo Hy-power antenna tuner. Specially a hc-400 which has what is termed steadtite variable capacitors which I think are 20-285 pf. I always thought that the tuner was rated for 850 watts based upon a sticker on the back of the unit. I recently acquired an amplifier rated for 800 watts and you can likely guess the rest of the story. Things were going fine for a few days until suddenly I heard definite arcing inside the tuner. I opened it up and to my horror the rotor plates are discolored and warped.

    Would anyone know a manufacturer and part number for these? My searching has been overwhelmingly confusing so far. I re-examined the sticker and the power rating is in reality 350 watts.

    Any suggestions are appreciated.

    Thanks, Tom WO1X
  2. AC0OB

    AC0OB Subscriber QRZ Page

    What is the height, width, length, and plate spacing of these, this cap? Picture?

  3. KL7AJ

    KL7AJ Ham Member QRZ Page

    If just a couple of plates are warped or burned you can remove them without noticing much, if any, difference.
  4. K6BSU

    K6BSU Ham Member QRZ Page

    Removing plates will not solve the spacing problem, if it is really too close for the amplifier''s power. BTW, high voltage on the capacitor will be greater if the SWR it also high. You can tune at lower power until SWR is low. Then increase the drive to the amp to full power.

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