[Antennaware] Grounding needs

[K9AY]

>I live in a 1 story home with a accessible attic.
>
> I have an Icom AH-4 tuner mounted in the attic, and need to run a real
> ground to the 8' ground rod we just pounded in.
>
> My question is - should the ground wire coming from the AH-4 be of a wire
> gauge of #12, or should I consider running 1/4" copper tubing?  The total
> length of the run is approximately 30'
>

Howard,

At a length of 30 feet, there is no RF "ground" -- it's nearly 1/4 
wavelength at 40M and will always be part of any antenna connected to the 
attic-mounted tuner. If you include the ground wire in a computer model of 
the antenna, this will be quite obvious. I have three suggestions:

1. Install the ground wire as short as possible, with as large a conductor 
as is practical. If the tuner and antennas work as you expect, you are 
finished.

If the antennas fail to perform as expected, or if the tuner behaves 
erratically, the new wire has created an unwanted resonance and/or increased 
the RF levels at the tuner. One of the two other options may work:

2. Add an RF choke in the power/control wires of the tuner -- ferrite beads 
or a few turns of all wires through a large toroid. This will "disconnect" 
the wires at RF.

3. Run multiple ground wires (e.g. 3) of different lengths to different 
ground rods. This will create different RF paths with different resonant 
behavior. Odds are that this will change things enough to reduce the 
problem.

73, Gary
K9AY