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Post by Deleted on Jan 18, 2016 22:32:44 GMT
Some are naturally disappointed by the 1/10th Watt of power allowed for legal Part 15 radio transmission, or, by the same token, equally downcast about the 3-meter antenna limit.
But my experience tells me the 100mW 3-meter figures were very intelligently calculated by the FCC as the right signal level to allow for compliance with 15.219.
Consider these observations and tell me if you don't agree...
About 6-feet from the metal window frame serving as the antenna for an AMT5000 transmitter is a Panasonic table radio tuned to that transmitter. The radio is very sensitive and extremely useful for DXing far away AM stations.
But with the AMT5000 set at exactly 100mW, the antenna length measured to a precise 3-meters, the radio is over-saturated and the audio sounds like it's coming from under water.
The FCC obviously calculated this delicate relationship, and with the further recognition that most Part 15 users are living near other households, any more power and Part 15 stations would be jamming their nearby neighbor's radios leading to a steep rise in complaints.
On the other side of the coin the Part 15 rule for FM, 15.239, is set ridiculously low without any obvious rationation, virtually guaranteeing violation of anyone trying to make use of the FM band for low power operation.
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Post by Admin on Jan 19, 2016 3:26:49 GMT
It would be interesting to know what the push was for the FCC to create the Part 15.239 rule. Was it Mr. Microphone from so many years ago or some other wireless "toy" such as that.
It seems if you are a manufacturer you can lobby the Feds for new application approval.
I suppose given the efficiency of small antennas at FM frequencies the FCC had to work the numbers to obtain a safe coverage area to mitigate interference complaints.
As of the last few years there has been some furor over the "IPOD" fm transmitters operating in the non-com part of the band where NPR stations work. Many complaints from people receiving interference to their favorite NPR station while driving in their car as the "IPOD" transmitter users are close by prompted action by the FCC.
So even though the restrictions for Part 15.239 make "broadcasting" as we do nearly a worthless endeavor we still strive to get the programs out there.
Perhaps one day, as the current chatter goes, the commercial AM and FM stations will succumb to "Streaming Stations" and we will inherit those bands with a new class of service for the license free, low power broadcaster.
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Post by thelegacy on Jan 31, 2016 0:03:15 GMT
As far as the Mr.Microphones and other wireless mics back in the early 70-1985 when finally the transmitters went digital there was an issue with drifting off frequency. So if 88.3 was blank and there was no channel 6 as well as 88.5 being blank the time it took for the transmitter to drift was less than 1/2 hour at times. So the transmitter started to jam nearby stations in the NPR Radio area. Plus remember those analog Radio's with the AFC as wide as a barn? Any signal that was stronger than the frequency your listening to would force tune your Radio to that frequency. I hated those damn Radio's. So that could have been what the deal is. But NOW 90% of the household Radio's are Digital. So that would not be an issue. Plus if the FCC banned non Digital Radio's to be sold. Sort of like the 23 channel CB when 40 Channels came out. This would make it easier for someone to tune into a Radio station. Even a talking Digital Radio for the Blind should be made. As far as AM goes I do agree the 100mW rule isn't too bad. Just think they should get rid of the antenna and ground rule. You can do a lot with 100 mW. And Station8 has proven that a fatter 6 foot antenna can beat a 9 foot antenna. So we just need to try and have better engineering for the AM side of things. My Talking House does a nice 1/4 mile to 1/2 mile from the Wire Antenna. This is placed indoors too. And having it near an electrical box causes a little carrier current effect which is not illegal. So I'm very pleased with what my Talking House AM Transmitter can do. I also learned that having the power supply plugged directly into the wall without a power strip makes better range too. Even the patch cords you plug into the talking house makes it go further if you have them as straight as you can. Didn't believe this till I experimented and found this to be true. We just need that company to machine the new 6 Ft antenna so we can get it off and running. Then we'll have 3 miles on a Talking House in an area where the interference is not bad.
FM needs to be petitioned with the FM Initiative to get things done for the better.
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Post by Druid Hills Radio on Feb 16, 2016 15:36:56 GMT
"And Station8 has proven that a fatter 6 foot antenna can beat a 9 foot antenna..."
Really? Fat antennas have wider bandwidth but not more efficiency.
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Post by Deleted on Feb 16, 2016 16:43:38 GMT
Fat but Short
The so-far secret experiments being done by Station8 have me between two mutually exclusive points of view...
On the one hand I know from radio school that longer is better for medium wave, I also hear talk in these days of "AM Revitalization" that shorter AM antennas are being invented by innovators as a way of solving the expense and large real-estate needed by conventional AM stations.
Of course Part 15 AM antennas are already short (3-meters) so I am very eager to hear how an even shorter design would be "more efficient", but it sure would be great if it is true.
Jeff Station8 is somebody I know and trust, so I'm very open minded about his project.
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Post by Admin on Feb 17, 2016 2:23:17 GMT
Kintronic Labs offers the Kinstar antenna system for MW broadcasters. It's basically a four legged folded wire monopole which is physically shorter than a standard 1/4 wave. Read about it here: The Kinstar MW AntennaIt has been approved for broadcast use by the FCC.
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Post by station8 on Feb 18, 2016 3:03:36 GMT
Hi Guys: As for 100 mW its not bad for some transmitters,But in some cases it would be better to have the fcc to give us approval to have a little more power do to all transmitter don't function the same in performances.
Also keep in mind it also depends on your antenna as well.
I have 23 part 15 am transmitter and seen so much power difference between each one its not funny.
I have 2 tx that were made from the Same company and I used the same complete set up,But got 2 different results in range.
But these tx should of had the same input power but guess what they did not!
Also keep in mind everyone different location is going to be an issue for that 100 mw range !
This is why in my personal opinion I don't see an issue with part 15 am power being increase legally.
Station 8
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Post by Druid Hills Radio on Mar 1, 2016 18:24:22 GMT
Kintronic Labs offers the Kinstar antenna system for MW broadcasters. It's basically a four legged folded wire monopole which is physically shorter than a standard 1/4 wave. Read about it here: The Kinstar MW AntennaIt has been approved for broadcast use by the FCC. I clicked the link but it says it's a bad link. Page not found.
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Post by Deleted on Mar 1, 2016 19:12:47 GMT
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Post by Druid Hills Radio on Mar 2, 2016 15:14:26 GMT
Yes thanks. I remember this antenna.
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Post by Admin on Mar 3, 2016 4:22:10 GMT
Thanks for fixing the link Carl. My link reaches the Kintronics page where you can type Kinstar in the search box and will come up.
That wasn't what the link was supposed to do.
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Post by Deleted on Dec 25, 2016 3:03:29 GMT
Thoughts About the Reason for Part 15 Intentional Radiators
Historically the phonograph oscillator, the original part 15 AM low power transmitter, was a cost-saving measure to keep the cost of phonographs low by eliminating on-board audio amplifiers.
Since everyone in the 1940s and 1950s had a radio, the inexpensive oscillator served as an input device to use the radio's power amplifier to listen to the record player.
It was genius experimenters at the time that realized the oscillators could be used as small radio stations and the hobby was born.
The modern FM dash-board automobile transmitters are the same thing... they serve as an input device to use the car radio's audio system to play audio from personal digital devices.
We are the modern geniuses who have inherited low power radio built from radio-audio wireless input devices.
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Post by End80 on Jan 12, 2017 20:22:04 GMT
Hi Guys: As for 100 mW its not bad for some transmitters,But in some cases it would be better to have the fcc to give us approval to have a little more power... ...This is why in my personal opinion I don't see an issue with part 15 am power being increase legally. As much as I would love that to happen, the reality is that it probably never will..
I suppose it is the personal opinion of most part 15 broadcasters that a legal power increase is a positive, but to the FCC it's a negative. It was Part 15.219 which ultimately resulted in giving us better range (then 15.204) was created in 1957, but it was never supposed to, and this fact is illustrated clearly in the history. Years later, in 1974, the FCC amended the 15.219 rule (then 15.115) to include the ground lead as part the 3 meter limit specifically for the reason to eliminate radiating grounds since it came to the attention of the FCC that such installations were providing much too much range.. I had contemplated that this might have corresponded with when Talking Houses began becoming wide spread use, but no, the TH didn't come into the picture until about 1985, so not sure what made it such an evident problem in the FCC eyes, but they definitely considered the extended range a problem, so they limited it. And then.. only a year and a half later, in 1976, when the FCC realized 15.219 was still enabling too much range even when extended ground were not used, they proposed more changes to 15.219 again, to absolutely insure the capable range could not exceed the same as 15.209.. Fortunately for us the FCC choose not to write those proposals into 15.219, but instead only included in Docket No. 20780, paragraph 16, a specific note that .219 was not intended to exceed .209. (By the way, I've been unable to pull up docket 20780 from the FCC site, perhaps some one else could? I may be searching it incorrectly).
It is Part 15 we are able to utilize for our stations, but it's purpose of existence is not really not so much for us, so our little stations are not much of a concern to the FCC at all. The entire purpose of part 15 is specifically for the reason to limit interference.. to increase our power limitations would actually mean increasing interference potentials - So for that reason, it seems very unlikely the FCC would ever allow increased power levels just for a niche group of individuals. I recently wrote about all this on my blog. The information was compiled from the research of Erma Roots, Neil-Radio8z, and most importantly from the history provided by John Reed of the FCC.. part15lab.blogspot.com/2017/01/origins-of-part-15-closer-look-at-15219.html
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Post by End80 on Jan 12, 2017 20:32:30 GMT
Of special note.. I never knew until recently, that originally .219 was supposed to be 200mw! That would make a big difference, to bad they lowered it to 100mw
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Post by thelegacy on Jan 12, 2017 20:42:38 GMT
In 1974-Mid 1975 it was getting very popular for a teen to get a hold of an AM Transmitter and have at it. In catalogues (Christmas Wish Book) you would see AM transmitters in them and they were quite appealing to a child at that age.
If your neighborhood youngster was able to transmit 2-3 miles with his little AM Transmitter and several other children did it too I could somewhat understand the concern. But with the Internet taking over we're looking at a new day and time where the coolness of a transmitter is not as intense.
So that said and the appeal of AM altogether is definitely not anything that a teen would ever care about these days. Face it the band is dying so why not loosen up the reigns and give hobby broadcasters something appealing and useful as 2 miles in range? Just some wise food for thought
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