possible dumb question

[holden]

Ray,

My thoughts on grounds.

They are vital for operator safety in any shack, for protection on the AC line,
and for lightning protection. This ground need not be a good RF ground.

There should be only one "ground" point inside any shack, and, as appropriate
(like for a ground-mounted vertical antenna) a ground at the antenna.  This helps
prevent common mode problems. This point should go DIRECTLY to earth ground. EACH
separate piece of equipment should have its own separate grounding line going to
the one ground point, no "daisy-chaining" here.

The quality of the earth ground may or may not be a factor in antenna operation.
If you are using a balanced feed antenna (dipole, doublet, J-pole, Zepp, etc.)
the ground is not  important for RF performance. Likewise, ground may or may not
help TFI/RFI.

If you are using a half wave or multiple thereof end fed antenna, while an RF
ground is necessary, it is not as critical from a current carrying standpoint as
it would be for a quarter wave or odd quarter wave multiple antenna. Voltage feed
vs current feed.

In light of the increasing use of microprocessor-controlled equipment in many
shacks, grounds become even more critical. Case in point: I am the primary
maintainer of a set of VHF UHF amateur repeaters in NNJ. We recent had to replace
our 2M machine due to a direct lightning hit. We decided to go '21st Century"
with both repeater and controller fully processor-controlled, no physical
switches or knobs.

We instantly encountered a serious desense problem with the receive side, which
came and went erratically. We completely revamped the ground system, new
interconnecting cables, relocating equipment, tweaking the cavity resonators, you
name it. In desparation we searched for a possible source of RF nearby in
frequency to our receive which might have been desensing us, and found that there
were myriad broadband spurs all around our input. The spurs were immediately
traced to the microprocessor-operated repeater controller. This controller was
mounted in the same rack as the repeater, but checks with an ohmmeter showed the
case panels were not grounded because of paint, anodizing on the rack, etc. Using
star washers on all case screws (to cut through the paint) and providing a proper
ground directly to the controller instantly cleared up the spurs. In this case,
the panels, floating from ground, actually acted as antennas, instead of shields
to contain the uP noise.

Ground is important, but in what capacity depends on each situation.

Howie WB2AWQ


rayfri wrote:

> This may be a dumb question, especially from someone who has been a ham for
> over 30 years..... BUT here goes anyway.
> How important really is a station ground to operation of a ham station?  I've
> operated with one, and without one in the past.
> Does it help with TVI and RFI, does it help with antenna operation, etc?
> To be honest, personally I havent noticed much difference, except for a few
> times
> I have been RF bitten in the shack....
> Ray  wa7itz

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