Common Mode Choke Question-Inverted L

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N1LOU, Dec 12, 2019.

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  1. EA1DDO

    EA1DDO Ham Member QRZ Page

    With no choke, the radiating antenna is from the end of the "L" all the way to the radio shack.
    When you install the choke at the remote tuner, then the radiating antenna will end there.

    73, Maximo
  2. KF5LJW

    KF5LJW Ham Member QRZ Page

    Does not have to be a Ground Rod. In fact at RF ground rods are the least effective. At frequencies above Power Frequencies, radials are the most effective. With that said what commercial operators use is a Ground Ring. Example a #6 AWG, solid, bare, and tinned conductor available at any electrical supply store.

    The most common error ham operators make is not bonding coax correctly. Just begging for Common Mode Noise, RFI, stray voltages, and invites lightning inside to make itself at home and smoke Lucky Strike.

  3. EA1DDO

    EA1DDO Ham Member QRZ Page

  4. N1LOU

    N1LOU Ham Member QRZ Page

    FWIW, I put a CMC at the entry to the shack and the problem is mostly eliminated. Once in a while while tuning up enough RFI sneaks through, but not often. I may throw the other choke on the tuner.
    N0TZU likes this.
  5. WA7ARK

    WA7ARK Ham Member QRZ Page

    Do you have a ground rod near the shack entry?

    If so, have you tried the CMC on either side of that ground rod?

    If so, which is more effective?
  6. AI3V

    AI3V Ham Member QRZ Page

    Please explain why the current dosn't "split" at the transmitter end of the coax, and flow both on the inside and outside of the coax shield.

  7. KK5JY

    KK5JY Ham Member QRZ Page

    Please explain how it can split on the transmitter end of the coax to flow on the outside shield?

    If that happened, it wouldn't be a "shield." The whole point of coaxial cable is containing the RF current to metallic surfaces inside the cable.
  8. AI3V

    AI3V Ham Member QRZ Page

    Again, when the electrons hit the very begining of the coax, what exactly keeps half of them from going on one side and half on the other?


  9. KK5JY

    KK5JY Ham Member QRZ Page

    I already answered your question.
  10. KN6CSB

    KN6CSB Ham Member QRZ Page

    what are you using to interface the coax to the aerial and radials? some sort of unun/balun I presume?

    I noticed nasty RF interference when I tried using a 4:1 current balun. I switched to using a 4:1 unun that specifically labeled the connections for antenna and ground/radials. Haven't noticed any common mode interference since I used that and added more radials. but it sounds like you have plenty of radials.

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