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Technical Rf capacitors

Discussion in 'The Hokey Ass Message Board' started by theHIGHLANDER, Aug 2, 2020.

  1. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,059

    theHIGHLANDER
    Member

    Gathering ignition schtuff for the flatty and it got me to thinkin (rare) have any of you used an RF capacitor for sound system needs while running the vintage plug wires? I ran one in my bracket racer to clean up electronics for the delay box and MSD, gained a 10th plus in 60' time, but it was big, like a pop can, and free. I know they can work but what's our fellow HAMB folk using? Thanks...
     
    Desoto291Hemi likes this.
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 46,866

    squirrel
    Member

    What kind of sound system? what kind of ignition system?

    OEM stuff....there was usually a small capacitor on the power side of the coil, to filter ignition noise for an AM radio. Corvettes used shields over the plug wires and distributors, because they had no metal firewall to block ignition noise. If you have a bad diode in an alternator, you're likely to hear a whining in the radio, frequency depends on rpm. Chokes are used to filter noise from power wires on many modern electronic things, you might have seen lumps on computer cables, that contain a ferrite ring.

    Big capacitors filter low frequency noise, small ones filter high frequency noise.
     
  3. BadgeZ28
    Joined: Oct 28, 2009
    Posts: 1,064

    BadgeZ28
    Member
    from Oregon

    Have you checked with auto audio installation parts companies or installers?
     
  4. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,059

    theHIGHLANDER
    Member

    I'll be running a semi-hidden modern bluetooth CD player and a 600W amp with a couple subs. I sort of figured the metal tubes for the plug wires will ground out some of it, but with modern electronics I'm not sure what's best which I why I thought to start a topic. Ignition is a Mallory dual point and the coil is the the old Holthouse. Wires are solid core. No ignition amps or the like, charging is a Powergen alternator. There's 2 condensors (capacitors really) involved in the coil get up. 1 is on the coil power lead, 1 on the distributor, and I figured those were for points life/control.
     

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 46,866

    squirrel
    Member

    Try it and see how it works.

    Sent from my Trimline
     
  6. continentaljohn
    Joined: Jul 24, 2002
    Posts: 4,629

    continentaljohn
    Member

    image.jpg How about something like this ? And made by Champion Sparkplug
     
  7. 4tford
    Joined: Aug 27, 2005
    Posts: 1,675

    4tford
    Member

    If you're running with no hood then RF radiated getting to the antenna. If you have a hood run ground strap from hood to body and make sue you have a good body ground. Running RF plugs will also help. The capacitors are for ripple noise on 12 volt power lines which if large enough you can also hear it on the radio.
     
  8. 302GMC
    Joined: Dec 15, 2005
    Posts: 6,263

    302GMC
    Member
    from Idaho

    We used to tie an overhand knot in the coil wire ..
     
  9. NGK still sells these in various ohm values... 5K ohms is a popular size. The only trick is you need a plug that has the 'old style' threaded top.
     

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