Re: A question about grounds
> Hello,
>
> Just a question about something you wrote.
>
> "If the supporting structure is metal, grounded, has another
> use, and is pre-existing, then the ground can be considered
> an unintentional radiator."
>
> Is this an "official" interpretation of grounding for part15
> AM. Just curious as to where it came from.
>
> Thanks.
>
> Neil
>
Neil,
Take a look at this diagram from Rangemaster and look carefully at the tower and it's ground lead to the radials or ground rod... Does this look legal?
http://www.am1000rangemaster.com/hints.pdf
http://www.am1000rangemaster.com/elradial.pdf
Rfry... you are the radio police here, please input your comments as well!
Below are FCC rules for reference:
[Code of Federal Regulations]
[Title 47, Volume 1, Parts 0 to 19]
[Revised as of October 1, 2000]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR15.203]
[Page 726-727]
TITLE 47--TELECOMMUNICATION
CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
PART 15--RADIO FREQUENCY DEVICES--Table of Contents
Subpart C--Intentional Radiators
Sec. 15.203 Antenna requirement.
An intentional radiator shall be designed to ensure that no antenna
other than that furnished by the responsible party shall be used with
the device. The use of a permanently attached antenna or of an antenna
that uses a unique coupling to the intentional radiator shall be
considered sufficient to comply with the provisions of this section. The
manufacturer may design the unit so that a broken antenna can be
replaced by the user, but the use of a standard antenna jack or
electrical connector is prohibited.
*****This requirement does not apply to carrier current devices or to devices operated under the provisions of Sec. 15.211, Sec. 15.213, Sec. 15.217, """"Sec. 15.219"""", or Sec. 15.221.*******
Further, this
[[Page 727]]
requirement does not apply to intentional radiators that must be
professionally installed, such as perimeter protection systems and some
field disturbance sensors, or to other intentional radiators which, in
accordance with Sec. 15.31(d), must be measured at the installation
site. However, the installer shall be responsible for ensuring that the
proper antenna is employed so that the limits in this part are not
exceeded.
[54 FR 17714, Apr. 25, 1989, as amended at 55 FR 28762, July 13, 1990]
See Sec. 15.219....
[Code of Federal Regulations]
[Title 47, Volume 1, Parts 0 to 19]
[Revised as of October 1, 2000]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR15.219]
[Page 732]
TITLE 47--TELECOMMUNICATION
CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
PART 15--RADIO FREQUENCY DEVICES--Table of Contents
Subpart C--Intentional Radiators
Sec. 15.219 Operation in the band 510-1705 kHz.
(a) The total input power to the final radio frequency stage
(exclusive of filament or heater power) shall not exceed 100 milliwatts.
****** (b) The total length of the transmission line, antenna and ground
lead (if used) shall not exceed 3 meters.******
(c) All emissions below 510 kHz or above 1705 kHz shall be
attenuated at least 20 dB below the level of the unmodulated carrier.
Determination of compliance with the 20 dB attenuation specification may
be based on measurements at the intentional radiator's antenna output
terminal unless the intentional radiator uses a permanently attached
antenna, in which case compliance shall be deomonstrated by measuring
the radiated emissions.
**** This rule says 3 meters total for the antenna and ground 'lead' if used...
This does not imply, what the attach point for the ground lead should be....
Radiopilot
<P ID="edit"><FONT class="small">
Edited by radiopilot on 01/02/06 09:35 PM.</FONT></P>