Is there a specific grounding wire you need to use to ground the Talking House ATU? Is there a type you reccomend that works best with the Talking House ATU?
Larger is better.
WDCX is right that a larger gauge wire transfers energy better than a smaller, thin wire, but I have always wondered...
Does it matter so much at the very small power levels of Part 15?
That is a true question and not at all a different opinion.
A wire gauge of 18 or larger wire (smaller gauge) will work as an RF ground but for safety you should consult local or national codes. Do a search on National Electric Code antenna grounding.
Here's an excerpt from the NEC:
"The grounding conductor shall be connected to the nearest
accessible location on the building grounding electrode, the
grounded interior metal water piping system or the power service
ground. The grounding conductor can run inside or outside the
building and shall not be smaller than no. 10 Copper or no 8
aluminum or no. 17 Copper-clad steel."
Neil
WDCX is right that a larger gauge wire transfers energy better than a smaller, thin wire, but I have always wondered...
RF travels on the surface of the conductor. So large is better than small regardless of power levels. Thanks, Neil for the code on grounding.
Thanks everyone for the help! 🙂
If one looks closely at the ATU, the shield of the coax is common to ground lug. So if the ATU is mounted very high the shield contributes to the radiation. And as Rich correctly points out, you now have an off-center fed vertical dipole.
The Talking House certification included the use of coax. This means the FCC accepted the use of coax.
Of course, you have to use it in a test chamber to lessen your chances of a NOUO...
Of course, you have to use it in a test chamber to lessen your chances of a NOUO...
Are you serious?
Yes. I can see your point and you are correct. There is no way to power the device without incurring additional AC ground length which you have stated results in a violation of the certification.
Therefore, the device would have to be installed exactly as it was tested, in a test chamber.
You did say the extra length incurred due to the AC gound system would violate the 3 meter rule.
You did say the extra length incurred due to the AC gound system would violate the 3 meter rule.
No. Only for those installations exceeding the limit permitted by FCC ¶15.219(b).
Of course if this or any of the other sub-paragraphs of FCC ¶15.219 are not met, then a field inspector might revert to ¶15.209.
NO...
Any installation connected to the AC ground system for use as an RF ground would exceed the limit permitted by FCC ¶15.219(b). Unless of course you isolate the AC ground at the receptacle and connect it to a non-radiating ground.
So, your choices are - earth. That rules out most any place besides outside or a house on a slab.
You can't back-pedal this. I agree with you. Plugging into the typical AC ground would create "installations exceeding the limit permitted by FCC ¶15.219(b)."
One can only assume these items would have been located on the table with the transmitter in the test chamber connected to a common power source.