Astron power supply is buzzing

Discussion in 'General Technical Questions and Answers' started by KB7QPS, Jun 23, 2015.

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  1. KB7QPS

    KB7QPS Ham Member QRZ Page

    I have an Astron VS-35M power supply for my Kenwood TS-440S radio. It buzzes when I transmit. A little bit on SBB (voice peaks). A lot on CW / RTTY.

    It didn't do this a few weeks ago, but I moved it from one shelf to another.

    I'm guessing RF is getting into the power supply. Besides moving my antenna 70' off the ground (not going to happen) or tuning my antenna to get from a 3:1 SWR to a better SWR (also not going to happen at this time), is there anything else I can do to prevent it from buzzing during transmit?
     
  2. K7KBN

    K7KBN Ham Member QRZ Page

    I'd guess the screws holding the laminations in the transformer tightly together have loosened. Open it up and retighten them - should be at least four of them.
     
    K9ASE likes this.
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    I would check the caps, and replace the bad ones. If it is not a RF problem.


    Good Luck.
     
  4. KE5MC

    KE5MC Premium Subscriber QRZ Page

    Could be the sheet metal case too as you just said you have recently moved it. While on a dummy load making power and buzzing place you hand on the case in various location and see if anything changes. Lift each corner slightly too and see if that changes the sound.
     
  5. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Not a problem. just don't worry about it. All my Astrons buzz a little too.
     
    K9ASE likes this.
  6. KB7QPS

    KB7QPS Ham Member QRZ Page

    Should have followed WA6MHZ's advice and ignored it. (It was loud though and bothersome)

    Opened the case, tightened down the screws. Did this three times. Third time forgot to drain the capacitator, saw some sparks on the screwdriver, and now the thing blows a fuse everytime I turn it on.

    Should have left well enough alone.
     
  7. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Not good news!! U now need to find out what still works.
    UNPLUG
    Take off the scews holding down the PCB to the cap
    move board out of the way, wires for bridge still to cap
    power on. See if youhave about 20V across the cap or across the diode bridge
    If fuse doesn't blow your XFMR and diode bridge are still good. IF it still blows, Diode bridge is shorted
    from there it gets complicated
     
  8. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    the buzzing is the transformer laminations. Nothing can be done about it, other than replacing the transformer. Doesn't affect operation whatsoever
    sorry U blew it up. Welcome to Ham Radio!
    if this is the worst you blow up in your Ham career, U got off really easy!!
     
    K0OKS likes this.
  9. W4HAY

    W4HAY Ham Member QRZ Page

    My RS-20M suddenly started making a very loud buzz when I transmitted. Tightening the bolts through the transformer laminations fixed the problem.

    Are you using slow-blow fuses? If so, check the bridge rectifier. There is a high inrush current that can take out ordinary fuses.
    (In some models only half of the bridge is used in a full wave circuit.)
     
  10. KA8CLN

    KA8CLN Ham Member QRZ Page

    Had the exact same problem occur on my Astron a few weeks ago, transformer buzzing. Replaced both DB3501 rectifier packs on my RS-35A, buzzing has stopped.

    Mine starting buzzing after being left on during a thunderstorm which made me suspect the rectifiers in the first place.

    Hope this helps.
     
    K8AI likes this.

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