Grounding Possibilities
 

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'

73's

Grounding Possibilities
 

Howard W3CQH wrote:
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'
========================================
That 30 ft run ,whether wire or tubing could possibly radiate RF ,hence
it might be better to have an artificial ground (a series resonant tuned
circuit + a length of insulated wire) located on the loft .
The unit is tuned for maximum current .

Such a unit can be easily homebrewed ,however it can also be purchased
from MFJ (their model MFJ-931) , be it that it is to be locally
operated which might be a problem when the Icom AH-4 tuner is remotely
operated away from the loft.

Frank GM0CSZ / KN6WH

Grounding Possibilities
 

Howard W3CQH wrote:
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'



Are you running that ground for RF reasons, or electrical safety
reasons? For instance, are you using it to match a dipole style antenna
or a vertical?

Is the antenna inside or outside?

For electrical safety, the coax shield will probably meet the NEC
requirements (assuming you've got the appropriate "shield to electrical
safety ground" connection at the bottom). And, if the antenna is
entirely inside, there's no issue with the NEC anyway.


From an RF resistance standpoint, the resistance difference between
1/4" copper tubing (3/8" OD (.375")) and AWG #12 (about 0.081 inch
diameter) is about 1:5 (skin effect means that you're really concerned
about circumference, rather than area). If you're interested in
reducing the RF resistance, using the shield of a piece of coax might be
better (i.e. it's larger in diameter, and the center isn't carrying any
current anyway).. But even for the AWG12, the resistance is pretty low
(sub 1 ohm for your 30 foot run)

From a RF impedance standpoint, the inductance is a bigger problem.
That 30 feet is about 10 microhenries, not to mention that it is
probably a good fraction of a wavelength or more.