[ICOM] Icom, Grounds and Mikes

[Jerry Keller]

My main concern with this system is lightning damage mitigation, even from close strikes...but from an RF ground perspective, it seems to play well enough. And so far I haven't had any audio problems.  But I was contemplating the purchase of a Heil Gold Line mic and from what you say I might be buying some problems. Thanks for the input, OM, very kind of you.

73,  Jerry K3BZ
  ----- Original Message ----- 
  From: David J. Ring, Jr. 
  To: ICOM Reflector 
  Sent: Friday, July 30, 2004 3:20 PM
  Subject: Re: [ICOM] Icom, Grounds and Mikes


  The traditional "fix" is to have ONE ground point, eliminating common
  grounding paths.

  In your set-up, you have at least TWO and probably THREE paths for
  grounding:

  1)    A.C. mains powered equipment to ground via the green wire to the A.C.
  power line service line ground.
  2)    Via coaxial cable to the SPG, but also from the tower there is another
  path, down the tower to the SPG -
  3)    From the electrical service entry box to the SPG.

  If you do develop any problems, I'd take off the equipment grounds and let
  the equipment ground via the coaxial cable.

  With all the connections, you have done a lot of work, but also should you
  have any problems, you can always disconnect any of the individual units.

  If it works, don't mess with it.  You probably have an excellent grounding
  system - but there are certainly different modes that "could" exist.
  Unfortunately there are different impedances for r.f., audio, and power
  grounds - which make the problem even more difficult - but you've done one
  important thing - you probably have a very very low loss ground and probably
  a very low impedance r.f. ground.

  73

  David N1EA

  ----- Original Message ----- 
  From: "Jerry Keller" <k3bz at arrl.net>
  To: "ICOM Reflector" <icom at mailman.qth.net>
  Sent: Friday, July 30, 2004 11:07 AM
  Subject: Re: [ICOM] Icom, Grounds and Mikes


  Dave... I have all my equipment chassis-grounded to a single copper bus that
  connects directly to a single point ground (large copper plate in a box) at
  the entry point to the shack. All of the equipment AC power cords are
  three-prong. Every coax line is grounded at the SPG and at the feedpoint.
  The SPG is bonded to a peripheral ground line that encircles the house and
  is bonded to the AC service ground. There are ground rods every 15 - 20 feet
  along the peripheral ground. The vertical and tower grounds are all bonded
  to the SPG. Seems to me this combines all power and RF grounds into a single
  common system with none of those "audio loops" you mention. Would you agree?
  If not, where do you see a problem?

  Any critical help or suggestions appreciated, 73 Jerry K3BZ
    ----- Original Message ----- 
    From: David J. Ring, Jr.
    To: ICOM Reflector
    Sent: Friday, July 30, 2004 1:06 AM
    Subject: Re: [ICOM] Icom, Grounds and Mikes


    Jerry,

    Ground loops (in audio) are caused by multiple grounding paths (audio
    ground).

    Sometimes a tape recorder (or some other auxilliary equipment such as
    equalizer or preamps) which using a grounded 3 pin USA electrical plug is
    plugged into a sound board, or recording mixer and it will cause a ground
    loop, but putting a 3 to 2 electrical adapter (and NOT using the ground
  pin
    to ground the adapter to the wall outlet) will solve this problem.  Now
  the
    tape recorder will be connected to the recording mixer only by the audio
    cable ground - and NOT by the electrical ground.  This eliminates the
  ground
    loop.

    Many audio engineers and audio recordists keep a few 3-to-2 adapters in
    their tool box just for this purpose.

    In ham radio, the ground loop problem can be solved by having only ONE
  path
    for ground.

    Western Electric (part of AT&T at one time) used to engineer a common
  ground
    at their medium wave radiotelephone stations at the antenna ground screen
    common point.  All the antennas ground screens and radial common points
  were
    lead to this common point, also the electrical local ground was at this
    point (green wire of AC wiring).

    Coaxial cables leading to transmitters grounded those transmitters at the
    Antenna Common Ground Screen Point.
    Likewise the receivers were connected to this ground via the coaxial
  cables.

    I know that there have been A.C. ground loops also.  Some of the symptoms
    were R.F. on the 120 VAC line.  I believe a similar cure for this was to
    install a single point of R.F. ground at the power pole line drop.  (A
    filter at the power company pole where it fed the radio station).  These
    A.C. ground loops would introduce regenerative distortion to r.f.
    transmitters.

    73

    David Ring, N1EA


    ----- Original Message ----- 
    From: "Jerry Keller" <k3bz at arrl.net>
    To: "ICOM Reflector" <icom at mailman.qth.net>
    Sent: Thursday, July 29, 2004 11:22 PM
    Subject: Re: [ICOM] Icom, Grounds and Mikes


    Bill.... I have a similar problem here, and I'll bet there's lots of us
  out
    here...so please let us all know what you figure out for reconnecting the
    station ground set-up. 73, Jerry K3BZ



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  Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
  Icom Users Net: Sundays, 1700Z, 14.316 MHz
  Icom FAQ: http://www.qsl.net/icom/

  ----
  Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
  Icom Users Net: Sundays, 1700Z, 14.316 MHz
  Icom FAQ: http://www.qsl.net/icom/