I think this is starting to make sense, maybe. My RF ground rod which is directly
under the station about 6' directly down, also ties to a series of additional rods
about 10 feet apart in both directions from that first rod (I am thinking this is
like a radial since the bare wire connecting them is also on the earth (?). Should
I connect the furthest rod of this series to the house mains ground rod which is
actually not that far away at that point? Would I be ok then?

-bill




Richard Clark wrote:

On Sat, 17 Apr 2004 18:42:44 GMT, zeno wrote:

Hi Bill,

By the points offered:

Then I turn around, and experienced hams are telling me the exact opposite, eg.
not to tie the RF ground to the house AC safety ground.

Experienced Amateurs (as distinct from experienced Professionals).

To tie the RF ground to
the house safety ground rod means a much longer run and thus the potential
problems of 1/4 wavelength resonance also mentioned here.

The basic confusion that arises is in the distinction between RF and
Mains ground. You can keep your RF ground rod (add some radials to it
to actually make it RF ground) as long as you tie it to the Mains
ground (usually in close proximity to the drop and meter). The
distance between THESE two points is immaterial RF wise as your RF
ground will insure little or no RF current travels to the Mains
ground. In THIS sense, they are separate.

If there is noise (RF) on the Mains, it may seek your RF ground
through this connection, but as long as you are not sharing it (you
are not using this lead to both connect your equipment AND connect the
two grounds) then there will be no problem.

You should have a lead from your equipment to the RF ground and THEN
to the Mains ground (two paths, one conductor) in that order:

MAINSGROUND-------------RFGROUND------------SHACK GOOD
MAINSGROUND----------SHACK-----------RFGROUND BAD

By the way, I am using an older Kenwood TS530S (until I get some experience and
decide to invest in a more current rig). Are current rigs now always with three
pronged polarized/grounded plugs? My unit here has a two prong non-polarized ac
plug, just like the old audio tube amps I still use for hi-fi.

Most rigs aren't AC powered at all - they require 13.6VDC that comes
from an AC powered DC supply. AC power is floating with a
Hot/Neutral. Neutral eventually finds ground but you are in jeopardy
of relying on that. Ground, the third wire, is a safety consideration
and is never expected to conduct current except as a consequence of
failure. Modern construction practices and code certainly mandates a
thick enough conductor, but not for the purpose of supporting power
needs.

In 1953 when I was first a novice, I used a bizarre little homemade transmitter
with one 117N7 tube which only plugged into one side of the house current!!!!

This is also from an era when newspapers reported the passing of
husbands or wives who, while washing the dishes, leaning on the stove,
playing with the toaster, putting down the iron, turning off the
mixer, or holding the refrigerator door.... leaned over to turn down
the radio volume - classic across the heart scenario - classic
results.

They were killed by "modern" engineering design techniques to reduce
noise (caps across the mains to the metal frame). Let's see, is it
suppose to plug in this way, or was it the oth.*#!!**#.....

73's
Richard Clark, KB7QHC

On Sat, 17 Apr 2004 20:15:21 GMT, zeno wrote:

I think this is starting to make sense, maybe. My RF ground rod which is directly
under the station about 6' directly down, also ties to a series of additional rods
about 10 feet apart in both directions from that first rod (I am thinking this is
like a radial since the bare wire connecting them is also on the earth (?).

Hi Bill,

The additional ground rods don't do much, RF-wise. You are far better
off with wire laid out radially on or just below the ground surface.
However, what you have is good.

Should I connect the furthest rod of this series to the house mains ground rod which is
actually not that far away at that point? Would I be ok then?

Depends on what you mean by furthest, but it sounds OK. Look at my
answer in the other post.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

The additional ground rods don't do much, RF-wise. You are far better

off with wire laid out radially on or just below the ground surface.
However, what you have is good.

How long should those radials be? and would just a couple be better than none?

Bill

On Sun, 18 Apr 2004 17:48:23 GMT, zeno wrote:
Richard Clark wrote:
The additional ground rods don't do much, RF-wise. You are far better
off with wire laid out radially on or just below the ground surface.
However, what you have is good.

How long should those radials be? and would just a couple be better than none?

Hi Bill,

The current is densest at the feed point for a quarterwave vertical.
Invest copper density in the first eighth wavelength with fewer
radials migrating out beyond there, and so on for as much as you can
tolerate.

The classic FCC grounds run from 112 to 120 quarterwave lengths to
give something like 95% shielding from ground (the point of radials).
Scaling does not follow a strict law of proportionality as 60 would be
85% effective. The proportion is more log based than arithmetic such
that a dozen (roughly a tenth of the FCC standard) would be at least
50% effective. Now, such pencil-whipping is based on abstractions
drawn from full quarterwave radials under a full quarterwave radiator
(classic field work for AM stations). As such, there are a lot of
variables to consider, and yet a dozen, eighthwave long would be a
solid RF ground.

However, few of us have properties that long/wide (without things in
the way) when trying to get into the 160M band game. So ultimately
you do what you can and don't gloat to those who know better. On the
flip side, 160M RF penetration into the ground is substantial and the
traditional ground rods do offer some advantage, and as Reggie offers,
so does the water service - find pipes.

Another myth exploded is when you hear DXers crow about horizontals
have no need of ground systems - they obviously have enough "gain" to
discard the 1 or more dB advantage in a ground screen below their
prima donna antenna.

RF ground serves many functions:
1. A reference to tune against (stability, a sink - what you seek);
2. A shield to reduce ground loss (more gain);
3. A reflector to enhance low propagation angles (more gain).

Please note that number 3 is offered for verticals only, at distances
of many wavelengths away - such is the advantage of shore placed
antennas. As such, "ground" is a misnomer (swamp, lake, ocean, or sea
serves instead) - and ignore the babble about the "conductivity" of
these being so much better. It is the drastic mismatch between the
æther and the body of water that does the DX charm, conductivity is in
the toilet.

73's
Richard Clark, KB7QHC