Tim -
Have you ever measured the daytime field intensity at that 7100-foot distance using your calibrated FI meter? If so, what value did you measure?
Also, have you used your Tecsun radio at that location to see what its dBµ display read when tuned to your station? If so, what did it show?
What is your carrier frequency?
15.23 says use good engineering practices to make sure equipment meets the standards to the greatest extent practicable.
I would guess the FCC knows the field strength 100 milliwatts can produce into a perfectly matched 3m antenna over perfect ground for the entire range of 510-1705 kHz. If they are investigating an unlicensed AM signal trying to determine if it is a pirate or a part 15 transmission, a reasonable first step would be to see if it is even physically possible for the measured field strength to be compliant with the constraints of 15.219. If it is possible for a part 15.219 compliant setup to generate the field, they may go on their way. If it is not, they will probably investigate.
So someone can have an elevated 15.219 install, but if they do anything that could be considered “gaming the system” they are not using good engineering practices to make sure their install meets the standard. The FCC does not care about electrical code grounding requirements; if a 15.219 compliant install and a NEC compliant install are mutually exclusive the FCC has no obligation to change 15.219. (For an example of the FCC not changing rules to help a sub set of people look at the FCC’s over the air reception rule, people with north facing balconies can’t receive satellite service but the FCC is not changing the rule just to help them. For example of the FCC not caring about grounding, the limited protections of the over the air reception rule do not allow a code compliant ground of satellite dishes installed on balconies unless the power entered the apartment/condo on the balcony.)
The AM elevated NOUO’s I have read all involved obvious (at least to the inspector) use of the ground/support to radiate. I have never seen a NOUO for an elevated install with the ground RF choked. So as long as someone is not trying to get extra range with an elevated install, they can probably show best engineering practices.
Here is an example of trying to game the system: Installing a range master at the top of a tower in a back yard. At the top of the tower the transmitter is not grounded to the pole, but at the bottom of the pole the ground side of the DC power cable and the audio shield are tied to the tower’s lightening ground radials. There could be radiation from the DC power and audio cables that would enhance the field strength. If the person has enough yard to put up a tower, they have enough space to do a unquestionably compliant ground install so the tower install is probably an attempt to get more range. (Note, the FCC does not care if your signal can clear obstacles around your property; they are just looking at the technical requirements of 15.219. Nothing in 15.219 or anywhere in part 15 gives you any right to your signal being receivable at some distance from your transmitter.)
Here is an example of best engineering processes for a balcony install: A talking house is setup on the balcony in a weather proof box. The supplied wire antenna is used, extending up as high as practical while staying in the space exclusively under the control of the balcony user and as allowed by the property owner. The supplied power supply is used and plugged into the closest convenient outlet preferably without an extension cord; if an extension cord is used it should have an RF ferrite core on it. Audio is fed with a standard audio cable; it should probably have an RF ferrite core.
If the only place someone can put an AM transmitter is on the roof of a building they cannot comply with 15.219 and NEC grounding requirements at the same time. In that case, the best option is to install the transmitter as close as possible to how the manufacturer recommends, put RF ferrite core’s on the power and the audio leads (to demonstrate an attempt to use best engineering practices), and ground the unit only through the audio and power leads with a surge suppression before the cables come inside. The goal would be to show that while lightening energy would get shunted off the lines to ground no RF would be radiated by the ground.
I did a ton of FS readings with my FIM when I first went on the air. If I can make sense out of two pages of yellow legal pad scribbling, at my "test parking lot" which is right on the 7100 foot line it looks like 80 uV/m. But I wouldn't swear to that and that could very well have been when I was in the experimental stages, so it may not have been my present permanent install. Generally I get reception past that spot on the car radio during the day but the background noise builds pretty quick so I consider that my fringe limit.
I'm at 1620.
I'm sure I tested for reception with the Tecsun but if I wrote anything down I can't find it. But it would be easy enough to stop and check. I tested reception all over the area when I was out with the FIM. I checked with the car radio, probably the Super Radio, a large portable Grundig, a crummy thrift store transistor radio and my daughters boom box that she had in high school (she's 30 now). All received OK in the parking lot. Couldn't get inside there to test any indoor reception. If I get a day when it's not raining (no snow yet thank heaven) I could take a quick FS reading at that spot.
TIB
.... If I get a day when it's not raining ... I could take a quick FS reading at that spot.
Thanks for your comments in Reply 18, Tim.
Hope you will have the opportunity/conditions to measure or confirm the field there with your calibrated FIM as well as the reading there on your Tecsun, and post whatever you find.
Quote from Neil and I agree. Enough already.
"
I am tired of obsessing about the rules as I think this is killing the hobby. We all want to operate legally and doing so is easy under 15.219 but we continually propose to exploit perceived loopholes and push the limits by applying our own definitions and interpretations to the rules which may or may not have factual basis."
Exactly. The only thing worse is hams obsessing over Part 97. Except they don't.
In Lansing, Michigan I've heard some really heated conversations about the rules. One was talking about RF exposure rules. It really got heated. But for the most part I dont see why they would get too heated about the rules. Hams are allowed a lot of power and can do quite well QRP when conditions are right. I didn't mean to hijack the topic. Just wanted to chime in on stuff I've heard while listening.
Well guys let's face it, the restrictions in my opinion are too limited.
Ham radio operators are allowed some leeway and that is a hobby just like part 15 broadcasting.
Listen I totally understand the reasons for the restrictions, it's to prevent interference to licensed radio services, but HAM radio can also cause interference to other radio services.
The difference being that HAM radio transceivers are built to filter out unwanted harmonics and potential interference, part 15 devices can be built the same way.
If a HAM says hey I was working China last night from California, the FCC does not come and hit them up with a fine, everyone's response is "Hey that's great!"
In part 15, you so much as say hey I reached 10 houses up the road last night and the response is "You're breaking the rules..you're a pirate.blah blah..blah.."
I'm not asking for the world, just a little more room to breath in this hobby without us alwyas being in fear of passing that limit.
Edited to add:
If people still want to break the rules after we are granted more leeway, then that is on them, but I still feel the current limit is too restrictive. If this industry can't come up with a transmitter that is well filtered to prevent harmful interference, then I don't know what to tell you, but I know it can be done.
Bruce.
Part 15 rules are like a cage.
Aspiring broadcasters voluntarilly enter the cage so they can broadcast legally for the pleasant experience of it.
Self-appointed keepers come along with sticks and start poking at the confined hobbyists through the bars of the cage.
Wanting a slightly bigger cage is not a violation of the rules.
Keep your stick out of my thread!
"Ham radio operators are allowed some leeway and that is a hobby just like part 15 broadcasting."
Not true. Ham operators have to follow FCC Rules as well.
"Listen I totally understand the reasons for the restrictions, it's to prevent interference to licensed radio services, but HAM radio can also cause interference to other radio services."
Very unusual in this day and age about interference. Generally it's the other way around. Hams typically receive interference from the same sources that plague AM radio.
"If a HAM says hey I was working China last night from California, the FCC does not come and hit them up with a fine, everyone's response is "Hey that's great!""
Why should the FCC come around?
I think the big difference here is that amatuer radio operators have a FCC issued license. Part 15 operators do not.
Well said WDCX.
WDCX said "Not true. Ham operators have to follow FCC Rules as well."
MrBruce says "Correct, but they are not as restricted as we are. I do understand RF power output rules are applied, but signal distance and range is not"
WDCX Said: "I think the big difference here is that amatuer radio operators have a FCC issued license. Part 15 operators do not."
MrBruce says: "I would be willing to apply for such a license, if need be, to operate such a part 15 station."
When I speak about a license, I'm not referring to a part 73 type license, just a form of registration with the FCC that I am allowed to operate a part 15 station with authroization.
Remember those old CB radio licenses? I realize those are no longer needed, but a similar license could be authorized for a part 15 station.
Bruce.
The other big difference between ham operators and Part 15'ers is that ham operators do not share spectrum with broadcasters - at least, broadcasters that the FCC receives money from and thus cares about (they do share spectrum with broadcasters on the 40 meter band, but those are on the other side of the world).
Good point ArtisanRadio in post #26
Although I do believe there is a HAM frequency in between VHF television's channels 4 and 5?
That is why the FCC should reallocate the frequencies below 50 MHz, perhaps the old Cordless telepone/baby monitor frequencies to a new expanded FM broadcast band for experimental purposes and also to relieve the current FM broadcast band congestion.
With more and more AM stations wanting FM translators, there is only so much original FM band spectrum left for any possible expansion.
Like it or not, the FCC is going to have to do something evetually, you can't make miracles happen when you've already exhausted the current 100 available channels already. If you think it's bad now, what about 5 years from now?
Bruce.
I realize this topic was about AM broadcasting with elevated antennas, I did introduce FM into the topic, because I felt it was, out of the available options avaialble to us, too limited in range.
Briefly I will mention something WDCX posted in another topic about a site called 49MHz club, the link: http://www.qsl.net/49mhz/ I seen that and wanted to share that here to compliment my request about opening up the frequencies below 50 MHz for FM part 15 experimentation (with extended range) purposes, including the broadcasting of music and entertainment.
I think a lot of you would agree, that we use AM because it has the most likely chance to be picked up by a public listener, but given if the restrictions for FM were changed and lifted, I believe more people would chose FM over AM as their mode of broadcasting.
Bruce.
"Although I do believe there is a HAM frequency in between VHF television's channels 4 and 5?"
That is incorrect. The 6 meter band is 50 to 54 below VHF TV channel 2.