Whistling sound

Discussion in 'Amateur Radio Amplifiers' started by AD5MD, Oct 14, 2017.

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  1. AD5MD

    AD5MD Ham Member QRZ Page

    Has anyone ever heard of a high pitch whistling like sound coming from the amp (SB-1000)? I hear it once in a while and then disappears. Any idea where it's coming from and what's causing it? thanks

    Ernie, AD5MD
     
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    May be the fan bearing. Does it stop or start if you tap the fan ?
     
  3. AD5MD

    AD5MD Ham Member QRZ Page

    Haven't tried but I'm guessing it could be the fan since it stops while in use the starts again after I turn off the amp. Will order a replacement, I hope it's not that difficult to replace it considering the space inside. Tnx
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    A fan bearing would make the same squeal whether you were transmitting or not.

    Does that happen, or does the noise occur only when you're actually transmitting?
     
  5. AD5MD

    AD5MD Ham Member QRZ Page

    It happens even on idle, comes and go so it most likely the fan
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I think that's probably true.

    If it happened only when you were transmitting, it could be an arc actually creating a sound (I've heard that) but if it's always there when the amp's turned on, probably the fan.
     
  7. AC0OB

    AC0OB Subscriber QRZ Page

    Also check the capacitor bank for any capacitor leakage.

    If the unit is Whistling Dixie, then someone has replaced the capacitors with Suthu'n caps. :)


    Phil
     
    ND6M likes this.
  8. N2SUB

    N2SUB Premium Subscriber QRZ Page

    I had an SB-200 that would do that. I was the fan. Once I replaced it, the noise was gone.
     
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    I have had good luck lubricating the fan.

    I use sewing machine oil. It seems to work good and can get into the bearing.

    If the blade wobbles it needs to be replaced.
     
  10. W0AAT

    W0AAT XML Subscriber QRZ Page

    HV arcs can whistle but you would probably be blowing fuses. I agree try lubing the fan. If that cures it you can get a spare fan and replace it when it gets noisy again.
     

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