Have no fear, mir, Part15.us does not kick people out!
I am not an official spokesman for the site, but over a very long time as a member I have noticed that the site is very democratic and welcomes everyone with a Part 15 interest.
Secret societies are not democratic, and these might include the nazi party of the 1930s, the ku klux klan, and a few that had best go unnamed.
Check out the windows to make sure everything is ok out in front of the house.
Comments have been made on various Part 15 boards (even recently) to the effect that this particular setup as described for Mr. Gaule using an FCC-certified Part 15 AM transmitter could not have produced the 1,800 µV/m field that the FCC measured at 175 meters.
The graphic below shows a NEC4.2 analysis of a system possibly similar to the one used by Mr. Gaule. The top of the antenna system is elevated 7 meters above the surface of the earth. A wire path representing the a-c wiring in the structure connects the transmitter chassis to a 3 meter buried conductor, which represents the utility ground rod at the service entrance.
The analysis shows that an r-f power of 60 mW applied to the input of the loading coil produces a field intensity of 1.8 mV/m (1,800 µV/m) at a horizontal distance of 0.175 km (175 meters). That field intensity was shown for that distance in the FCC NOUO issued to Mr. Gaule, for this 1700 kHz frequency.
The two outlined areas shown in the left pane of the graphic give some of the relevant parameters of this study.
So it does not appear to be unpredictable or mysterious that a system such as this could produce the field measured by the FCC at that distance -- whether or not its transmitter was FCC-certified for Part 15 AM.
Right clicking on the image and choosing "View Image" will bring up a larger-sized image (in Firefox, anyway).
While having no doubt about your finding, Rich, which has been published before, you don't mention taking into account that Mr. Gaule's equipment was reported as being indoors and not out on open ground.
It would be interesting to hear whether operating a seemingly compliant system from an indoor location could achieve the fields readings claimed in the NOUO.
It also remains entirely baffling that rule 15.219 was never mentioned in the NOUO, which demands its own explanation.
Normal residential structures built without an above-ground steel framework to support them essentially are transparent to radio waves in the medium-wave band.
So far no description has been given on Part 15 boards about the construction of the building wherein this transmit system allegedly was installed. But unless that was in a "high-rise" type structure, probably it would not make much difference to the field that the FCC measured 175 meters away.
I also wonder why there was no reference to 15.219 in this NOUO.
Google Street View indicates 2 story wood framed structure.
Yes, field strength would seem to be a moot point if the unit was operated as described.
The original story stated the Talking House was on the floor, using the supplied wire antenna with internal auto-tuning, the wire strung vertically from floor to ceiling.
No mention of interference to other services was noted.
As such, the unit being certified for Part 15.219 use would have satisfied that requirement.
The question remains; why was this installation challenged as a Part 15.209 violation of field strength?
The original story stated the Talking House was on the floor, using the supplied wire antenna with internal auto-tuning, the wire strung vertically from floor to ceiling. ... As such, the unit being certified for Part 15.219 use would have satisfied that requirement.
But what if a system FCC-certified under Part 15.219 was installed such that it did not comply with all of Part 15.219 -- in that the radiating length of its antenna system was greater than the 3-meter length permitted by Part 15.219(b), whether or not such was recognized by its installer/operator ?
But what if a system FCC-certified under Part 15.219 was installed such that it did not comply with all of Part 15.219
Then it would fall under Part 15.209 and if the field strength was in excess of that it would be in violation.
antenna system was greater than the 3-meter length permitted by Part 15.219(b), whether or not such was recognized by its installer/operator
But, as the situation was reported, the Talking House was setup using the proper power supply and antenna wire. Are you insinuating the power supply ground system is the problem? This seems to be the only "unknown" as the AC ground length to earth is unknown.
When the device was certified the method of gounding was taken into consideration so I fail to see how that is a factor. Now, if a separate grounding wire was attached to some point of the system this could be a problem. But, none was reported to have been used.
So, other than the supplied wire antenna and accepted gounding method, where do you suspect the extra length is found?
Member Rich wrote:
"But what if a system FCC-certified under Part 15.219 was installed such that it did not comply with all of Part 15.219"
But you see, if that were the case, the NOUO would need to specify in writing that the transmitter did not comply with 15.219.
Trouble is, the NOUO didn't reference 15.219 one way or the other.
Now, if a separate grounding wire was attached to some point of the system this could be a problem.
But what is the difference as far as physics is concerned whether such a grounding wire is one of three conductors in the a-c house wiring that connects the transmitter chassis to a buried ground rod at the service entrance, or a single conductor separate from the a-c house wiring that connects the transmitter chassis to the buried ground rod?
The fact is that the electrical conditions at radio frequencies present at the connection point at the top of the ground rod are not the same as at the connection point at the other end of a "ground wire" connected between the ground rod and the transmitter.
Both such conductors add radiating length to the ~3-meter whip considered to be "the antenna."
The difference is the FCC OET test included the use of the AC ground. AC grounding is described in the patent information supplied for certification. The FCC accepted the fact that the AC ground, regardless of where it runs, is the system ground.
Without researching the entire situation of Mr. Gaule but taking Rich's statement that he was operating at 1700 kHz it is possible that the signal had components above 1705 kHz for which a much lower field strength limit applies compared to below this frequency. Could it be that this is the reason for the cite under 15.209?
A bit of a stretch, perhaps equivalent to a dusty tail light, but perhaps the rationale.
Neil
Someone complained.
No interference problem was noted, only field strength. It would answer a lot if the NOUO explained what the alleged complaint was.
Channels are 10 kHz, +/- 5 kHz from center so sideband energy at 1705 would be normal, yes? What commercial station stays within channel especially the digital stations?
The difference is the FCC OET test included the use of the AC ground. AC grounding is described in the patent information supplied for certification. The FCC accepted the fact that the AC ground, regardless of where it runs, is the system ground.
Measuring the added radiation from the "ground" conductor(s) of the a-c wiring of a building that are used to connect the chassis of a Part 15 AM transmitter to a non-radiating r-f ground of a Part 15 AM system (such as a buried ground rod) most likely was not included in the compliance testing of that system.
Probably those compliance tests were conducted in an anechoic chamber which volume would not permit the emulation of a system installed on the second floor of an apartment building.
Even if those tests were conducted at a "Open Air Test Site" (OATS), it would be highly unlikely that such a structure/installation would have been used there.
The FCC accepts/certifies a Part 15 product based on the test conditions and data they collect.
But if a buyer/installer/user of that product does not follow the installation configuration described in the FCC compliance test and certification, then it is reasonable to predict that s/he may be at increased risk for an FCC NOUO.