With the many good opinions and ideas being put forward I would like to remind readers of a few things:
CFL light bulbs produce unintentional radiation while Part 15 transmitters produce intentional radiation, using the FCC's own language.
If our radiation is "intentional" it stands to reason that we are viewed as senders of program material with no restrictions given as to content.
It is therefore unfair to call Part 15 intentional radiations "interference."
Matter of fact the only restriction required by FCC Part 15 Rules for AM & FM are technical restrictions. Except for that, intentional radiations can be anything you want them to be.
As for Rich's latest ad hominem: "Gibberish, Mr. Blare," he is still agonizing over a post I made days ago in another thread which is actually "palaver," to use the correct word.
To avoid disruption of this thread, I am again inviting Rich to join us at the ALPB Meetings where Part 15 issues are on the table.
As I mentioned on the revitalization of AM thread that the noise level here is 4 out of 5 blocks on the Grundig 450 Radio I use for tuning and monitoring my AM Transmitter. Listeners complain and question my sanity for even wasting time with AM. If the transmitter was not donated I would sell it for a Ramsey 100BEX FM transmitter or at least something like an EDM. The almost $300 for an AM TX could have got me a super nice FM Transmitter that would be a dream to any Album Rocker. If I move from where I live I can only hope the interference is not so bad. But there is really little hope for AM here.
TheLegacy,
Brother I am starting to feel your pain.
I don't care what federally backed trolls monitor this forum, the fact of the matter is these rules were made back when the noise level in America was almost 0%.
The noise floor was nominal back when these rules were drafted and radio's were built with pride and dedictation. Now we have millions of devices and our own power grid wiping out reception of even the most powerful Am stations across the nation.
I want my house to be noise free, no not the kids but the RFI, EMI generated by the microwave oven, cell phone chargers, tablet chargers, wall warts, wifi and the power line control singals. I have nagged about turning off the wifi and installing ethernet cables all through the house just to eliminate some racket from the cheap motorola modem. (wife isn't having it)
To enjoy radio, i mean really enjoy it, I need to make like a hippy and be one with my radio in a field of daisys and cows. I don't have that luxury though and so I have to hope for a power failure just so I can enjoy my radio.
As for Part 15 AM, yup you guessed it. Noisy as hell here on the mountain.
My newly aquired SSTran has a nice signal outside in the yard and past two houses on either side of me. Past that, power line noise wipes my station out completely.
I really expected my signal to be hampered by the mountains but that is not the case here.
Part 15 FM? PFFT, forget about it. That is 4 homes on my road, that is if the signal even penetrates those homes. Highly doubtful.
I find it funny too, not in a ha ha kind of way, but the rules plastered on the FCC website state 200 feet for both AM and FM. Say what??
Quoted from the FCC Website:
Unlicensed operation on the AM and FM radio broadcast bands is permitted for some extremely low powered devices covered under Part 15 of the FCC's rules. On FM frequencies, these devices are limited to an effective service range of approximately 200 feet (61 meters). See 47 CFR (Code of Federal Regulations) Section 15.239, and the July 24, 1991 Public Notice. On the AM broadcast band, these devices are limited to an effective service range of approximately 200 feet (61 meters). See 47 CFR Sections 15.207, 15.209, 15.219, and 15.221. These devices must accept any interference caused by any other operation, which may further limit the effective service range.
For more information on Part 15 devices, please see OET Bulletin No. 63 ("Understanding the FCC Regulations for Low-Power, Non-Licensed Transmitters"). Questions not answered by this Bulletin can be directed to the FCC's Office of Engineering and Technology, Customer Service Branch, at the Columbia, Maryland office, phone (301) 362 - 3000, OET Laboratory Division help page and search for "Part 15".
End quote.
So, here we are trying to squeeze more than 200 feet of effective service range out of these puny transmitters. Are we legal? I don't know. Maybe , maybe not. Perhaps 200 feet is all our illustrius government thought we could handle, you know since we are all beligerant citizens bent on taking over the airwaves.
I wonder sometimes why i quit running a pirate radio station years ago, the reason I ran a few watts on FM back then was the range was pitiful. 200 feet in the middle of no where with only 2 neighbors close enough to hear my signal and over 100 potential listeners further way.
I don't pirate now and I don't intend to ever start again, I am too poor to pay attention and I dam sure cannot afford a $10,000 fine, because believe me I like to challenge authority and an NOUO would just challenge me to continue broadcasting over the limit.
This is by far the most frustrating hobby I have ever dealt with and these tight rules are outdated, things have changed. Noise is on rise in the AM and SW bands and the FCC could care less. It seems all they care about right now is more ways to connect to the interent wirelessly , even if it means re-locating or shutting down t.v. stations across America.
Off my soapbox now, let the bashing being.
Barry of Blue Bucket Radio - all two hundred feet of it.
EDITED: I forgot to attach a picture from Google Earth, this is what 200 feet gets me here.
Rock 957 is pretty much spot on about noise levels of the time.
There used to be a time where the FCC went after utility companies with noisy lines. Some utils still like being informed when their lines get annoying, that being said I haven't tried lately.
I think higher power levels in part 15 would only be a patch to a much larger problem at hand. The ammount of interference these devices pump out should be considered unacceptable. I think the FCC needs to tighten regulations on unintentional radiators, thats what we need to be pushing for. That might actually get us somewhere.
Im glad someone is on the same ]age.
Right on the money about AM. I went on a big rant about this subject of AM and the noise from hydro(A/C power) and the demise of the AM band because of it in past posts.
The FCC doesn't care because most people don't care. I grew up on AM radio...in the 50s 60s and 70s AM was king...and clean. Spent evenings for years listening to stations all around the USA from Toronto....no electrical noise!
If I were to have my hobby station on AM now no one would listen...even the people that are my age wouldn't...'cause they can't.
Fortunately here in Canada we have a classification of unlicenced use that allows a hobby station to get a decent signal to an immediate small neighbourhood with FM.
If you want to see how AM used to be turn off the Hydro in your house for a bit and enjoy a revitalized AM band!
Mark
Tim's field tests have given us a never before available look at what typical certified Part 15 FM transmitters are doing.
Right at the same time I obtained a new C.Crane FM2 and, keeping in mind Tim's finding that adding audio cables sometimes increases the radiated power, I have added a 10-foot extension to the audio so I can locate the transmitter over there.
On the spectrum analyzer the field strength increased 2 dBu.
What I did to compensate was collapse the telescoping antenna of the transmitter until it was back down by 2 dBu, thus now having the audio extension and retaining the certified output.
Some would not agree, but Part 15 operators are good thinkers.
I thought about the C. Crane because of the great Audio quality it has. How does the harmonics and spurs on the spectrum analyzer? That is something I'd like to know.
Both C.Crane FM1 and FM2 are clean and have no harmonics or spurs.
I don't know how they do it, but up above the FM band the spectrum analyzer shows some very slight blips, but they are NOT coming from the C.Cranes, because turning the transmitters off does not make those blips vanish.
Hold on, hold on, I went to the 2nd harmonic of 89.9, which is 179.8 MHz, and I see a very low level signal that is 22 dB below the main carrier, making it legal with 15.209.
Some wonderful news about the C. Crane Carl. Its really the best news I have heard about an FM Transmitter.
Has anyone tested the C Crane FM2 in a hot environment for an extended period, such as an attic?
The Manual for C.Crane FM2 says:
Heat: Never put the FM Transmitter 2 in direct sunlight or behind glass such as a car's interior. The transmitter should be kept away from heat sources such as radiators, heat registers, stoves, or other appliances that produce heat.
An attic probably gets just as hot as a car's interior, so I'd not risk it.
Maybe there are ways of keeping it cooled down with equipment fans.
A thought about why you got 3dB less with A/C.
Looked carefully at the schematic of C.crane FM 2 on FCC site.
The DC power( 3-6volts )whether applied to the adaptor jack or the battery compartment terminals is the same thing with a switching diode to have auto. power switching to battery if power goes out. Makes no difference where power is applied....goes straight to a regulator that supplies 2.5 volts to the transmitter. You can put 4 AAs( 6v )in the battery compartment instead of 2 AAs...doesn't matter, 2.5 volts is still what the regulator supplies the transmitter....so why the loss of output with the adaptor?.....by adding more antenna via the 6 ft cord from the A/C adaptor you added "too much" antenna combining with the 6ft audio cable and created a mismatch which resulted in a drop in field strength.
This is really a good transmitter that sounds as good as any of them...even Decades, and the transmitter chip(S14710 DSP) has compression/limiting that actually works.
Mark
Although the sound is quite good (no scientific testing done in this regard) is is still limited in range by the rules like all the legal transmitters.
This past weekend I wondered what kind of range it would give if I simply set it in the window of my storefront office on main street. With it cranked to full (very illegal) high power, a 3 meter field strength of 5850 uV/m (remember the legal limit is 250 uV/m) it got just short of half a block -- this from across the street with the transmitter in plain view in the window to where I was standing. It did better in the open testing field, but few of us set up out stations in a large open field far away from anyone who could possibly hear us, so this was an unofficial test in the "real world".
All this showed me is that, as I've believed all along, that attempts at legal Part 15 "broadcasting" are more trouble than they're worth. I can't imagine the coverage with it set at the legal limit. But remember too that the two certified transmitters I tested were well above the high power of the C. Crane and didn't have much more range.
I just may be putting this C. Crane up for sale. I can find no reason to use it for anything.
TIB
TIB - Was the ~ 1/2-block range described in Reply 59 above consistent for all compass bearings from the transmitter?
Especially in an "urban" environment, radiated signals of 30 MHz and above are subject to multipath effects which can either reduce or augment the field arriving on the line-of-sight path.
Might your signal have had much better range in some other directions?