Connect with us

AM Radio =-interference- Is there a plug-in or easy filter

Discussion in 'Electronic Repair' started by [email protected], Nov 17, 2013.

Scroll to continue with content
  1. Guest

    I have a 1970's GE clock transistor radio. On AM stations, (1060) there is a lot of buzz/hum. However when I turn ON various CFL light fixtures around the house, the hum disappears. Is there a filter commercially available to put on the AC line? Or can I make one? I've tried reversing the plug (that used to work years ago). Any suggestions? TIA- vze2m645 at verayzon dot nat, you know what I mean.
  2. Phil Allison

    Phil Allison Guest

    ** Still working ??
    ** The usual cause is AC supply frequency modulation of AM radio signals
    arriving on power wiring in the premises.
    ** CFLs nearly all have a 100nF or 220nF capacitor that connects directly
    across the incoming AC wires. These reduce any AM band signals to a much
    lower level and so avoid the aforementioned supply frequency modulation.

    ** Doubt it.
    ** A 1uF, 275VAC cap is all you need.

    Wired into the back of a regular AC plug.

    .... Phil
  3. michaelm

    michaelm Guest

    Thnks Phil. does that cap go in series with one lead of an ACPlug, or across thepower line.
  4. Phil Allison

    Phil Allison Guest


    ** Fix you fucking settings !!!!!!!!!!!!!!

    And learn how to read.

    ..... Phil
  5. Learn how to spell !!!!!!!!!!!!!

    And, get OE Fix, too. :)

    In all fairness to Phil, after he had his grumpy juice for
    breakfast, he did state to put the capacitor across the
    incoming AC line i.e. parallel. With a molded plug you would
    have to be quite clever, but you may buy a replacement, two
    piece plug and wire the capacitor into the circuit, minding
    to heat shrink the capacitor leads.
  6. Guest

    Forget it, none of this shit is going to work. The simple fact is that there is so much shit putting out interference in that band that nothing is going to eliminate it.

    You can't shield it from the power line because it is conming in from THE ANTENNA ! You would have to filter the frequencies you want to recieve.

    It's different when you are out in a truck on the highway in bumfuct Kansassomewhere. Then AM can work.

    Think about it, AM is about one megacycle. Yup, not even Hertz. It's that old. I hate to say it, but AM is just about dead. I used to like CKLW. In fact CKLW used to be one of the most popular stations in the whole country. The problem now is that even your fucking clothes apparently enamate RF in that low band.

    Shortwave is just as bad.

    There is a damn good reason that the technology has tended toward higher frequencies. In fact, like OVER ten years ago I advocated the elimnination ofthe VHF band for television. On channel 3 (US, about 60 Mhz) if a car was driving down the road and had a bad spark plug wire it would cause interference.

    **** that.
  7. You seem to be retarded. The OP already stated that the noise was eliminated by
    turning on a CFL.

    If the OP could kill the power to the receptacle, solder some extension wire to the
    cap leads, and then wire the cap across the back of the receptacle. Minding to heat
    shrink the leads of the cap, and using a larger heat shrink, encapsulate the cap and
    all of the smaller heat shrink. Make the extension leads 6" long.
  8. mike

    mike Guest

    Wouldn't it be easier to put the cap inside the radio?

    Be careful with your choice of cap.
    I put a quality 600V cap across 220VAC inside the dryer to
    bridge the phases to make X10 work. Worked great for two
    years before it exploded spectacularly. Good thing it was
    inside a metal box.
  9. Phil Allison

    Phil Allison Guest


    ** Get a life - you fucking IDIOT !!!!!!
  10. Phil Allison

    Phil Allison Guest


    Forget it, none of this shit is going to work.

    ** So you do not understand the issue.

    AM radio often signals "piggy back" into premises on the AC power and are
    then re- radiated with supply frequency related modulation - mainly 100
    or 120Hz and harmonics.

    They also arrive by penetrating walls and windows without such modulation.

    The loopstick antenna in the OP's radio picks up either or both.

    It may even have a small cap connecting to the incoming AC to enhance the

    Get it now?

    ..... Phil
  11. Phil Allison

    Phil Allison Guest


    ** Worth a try - if it will fit.

    ** My post specified a 275VAC cap ( aka class X1 or X2 suppression caps) .

    These are specially would to avoid internal corona that destroys ordinary
    film caps wired across the AC line.

    If you cannot get any, try two 600V film caps in series - that ought to
    work OK too.

    ..... Phil
  12. Guest

    What the ****.
    Yeah well my shit that I design and build works.

    What say you ?
  13. Guest

    Zanother thing. You think you can prevent a reciever from recieving that which to it is tuned ? All that fucking noise is right there in the passband.

    who the **** here is so damn good that they cn selectively reject the noise wehn it is in the same bandw, and frequency, as the desired signsl ?

    I don't know what kind of schoopkls they got down under, b ut in between buxting your heads and shit, they must be pretty fucking good.

    Look up Lewin A.R.W. Edwards if you want to see a REAL resume'. In fact he toned his resume' down a bit. Maybe it wss embarrassing too many people.

    Know what I say when this shit happens ?

  14. Guest

    God damn am I toast right now.
  15. wrote in message
    If RFI is coming down the power line, it can be choked before it reaches the

    I've done this with FM tuners. It reduces multipath that gets in through the
    power line and the antenna cable's shield.
  16. Not if the window glass is "Low-E" and the walls are stucco.
    Such dwellings are almost a Faraday cage.
    I live in one. Most of my AM reception is of RF trash
    generated _inside_ the house.
  17. I found this idea on a web page from a company that makes small high gain
    antennas for shortwave listening.

    Take a portable radio and find the end of the "noise cloud" around your
    home an put an antenna there. Of course if you are in a tight urban
    area, or an apartment, you may never find it. :-(

  18. I remember forty years ago I could just stick a few feet of wire on the
    SP-600 and reception was fine. Now, there is so much noise from all the
    electronic junk that didn't exist back then, that you really need the
    antenna outside, or at the very least, next to the window. The signals
    suddenly leap out, but it's a combination of stronger signals from
    outside, and weaker signals from inside.

  19. amdx

    amdx Guest

    However when I turn ON various CFL light fixtures around the house, the
    hum disappears.

    Leave the light on!
    Put a shade on it?
    Paint it black?
  20. Guest

    "Now, there is so much noise from all the
    electronic junk that didn't exist back then..."

    That's what I'm talking about. These days if it ain't Ghz there is all kindof noise all over the place. Sure there is some on the power lines etc., but it is also in the air.

    Just for a test, if anyone is so inclined, just take a scope probe and connect it to a big piece of metal. You are going to see more shit there than.... well, I lack a proper metaphor at this moment. Sorry. But there is alot. Sometimes I'm surprised anything works.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day