I'm more inclined to believe they just evolved that way.
Obviously they evolved into something besides what they once were when they were written in clear distinctive language. Part 15 is not a major part of the FCC's management of the spectrum duties. It is only a tiny fraction of it, as so you can clearly see when looking at Part 15 versus Part 73 or 79...much more detailed and concise...because those are "bigger fish" to fry...literally.
What has become Part15 public broadcasting is an entirely different creature than garage door openers and home security systems, and should have been treated as such when it's existence became evident.
Yes, indeed different from yesteryear to today..even so when the Part 15 section was first revised in 89....the so called "Part 15 public broadcasting" was not so much of in existence during that year. The Part 15 rules have not been revised since what...92? Here it is 2011, and between 1992 and 2011, Part 15 public broadcasting become more in of existence. So here we all are trying to apply rules written when Part 15 public broadcasting was not so in existence in a time when it IS in more of existence....quite a big pot hole in the road wouldn't you say?
So again, I will state that us radio people, most of which out here are licensed HAM's, must use our radio engineering knowledge and good ol common sense to find that compliant level out of the controversial rules as they are today.
I am sure that you licensed HAM operators are not going to just throw things to the wind simply because you have a piece of paper with the "Great Seal of the FCC" stamped on it. You will use your knowledge of radio engineering and common sense..right? Just as you have when you began to apply for those licenses..you had to have pre knowledge of radio engineering and electronics...right? They don't just hand you a ticket like it used to be for CB by simply filling out some card and sending it in. You have to know a thing or two about radio, transmitters, antennas, radio energy propagation, interference potentials and remedies, building proper systems using "good engineering practices". All pointing to the fact that you must "use your head and the brain within" in order to earn that license.
For the sake of Part 15, a section of the FCC rules setting the standards and limits for unlicensed transmitters, no matter if it is 1950 or 2011, the FCC expects you to use the same good engineering practices and knowledge and common sense as used in obtaining your HAM ticket to begin with. Bottom line is that there really is no difference between the two except that one comes with a license, the other does not and that one allows for the use of power levels in the watts range and the other limits you to the flea power range. But there is no difference in the two when it comes to the bottom line..staying within compliance.
Until they do write these rules so that we can clearly see what is meant for Part 15 public broadcasting, we therefore must use our better judgments and experiences as radio engineers and station operators/owners...plain and simple. And in that respect, using our knowledge and experience is the best sure fire way to comply, regardless of how confusing or contradicting the rules are currently written.
No one says you must drive down road A to reach point B when you have 5 paths to choose from and 3 of them are flooded, one has a downed tree and the other is clear. But yet it is so surprising to see that even a layman would know the blocked roads would give less chances of reaching point B, but take them anyway because they are shorter to point B than the clear road is. Is that using common sense and knowledge?
Hardly.
One thing we all can agree with here is that Part 15 is a highly controversial subject to begin with, especially for broadcasting to the public and not so much with using garage door openers or baby monitors. Clearly the revised Part 15 rules points more to those latter devices than a device intended to broadcast to the people, but devices that are designed to broadcast to the people are there and some carrying certification. Even with that, in the end it relies on the operator/owner to use them in compliance which is what is expected from the FCC prospective.
Someday our hobby, key word there, will be recognized a bit more by the FCC and in turn write some rules specifically for public broadcasting at low power levels. So what do we do until then?
I say we use plain ol common sense and good judgments with respect to the cluster mess of the rules. At least we can say to ourselves, and to the inspecting FCC agent, we did just that to comply.
RFB
RFB, thank you for your effort to clarify this discussion but we are not yet in agreement. First, my reference is the Part 15 rules themselves, not the OET 63 bulletin you mentioned. My copy has a cover letter which states "The following Part 15 regulations contain all updates and changes adopted and released by the Commission as of September 19, 2005."
Part 15.25 clearly and specifically states that this section applies to a TV interface device and does not include nor mention other kits such as those intended for operation in the AM broadcast band.
Further indication of the lack of restriction is demonstrated by the fact that the two kits I have purchased both provide an antenna jack which is a RCA phono pin connector.
Regarding my modifications to my Ramsey AM-25 transmitter, your analysis appears to be based on the contents of Part 15.209 in which case doubling the output power and/or changing the antenna could result in non-compliant operation. However, I am operating under the rules of Part 15.219. Using the definition of efficiency as RF power out divided by DC power into the final it is easy to see how doubling the efficiency can double the output power while keeping the input power constant. Since 15.219 only limits the DC power into the final and does not address the efficiency of the final there is no conflict with the rules with increased efficiency. Part 15.219 does not address the field strength but combines a limit on the final input power with antenna system restrictions as a de facto limit on field strength so it becomes unnecessary to actually measure the field strength.
You made two comments:
1. You changed out components and their values in the output network that obviously are not of the design parameters which allows this kit to be marketed and used under the Part 15 rules, thus taking the kit outside of being compliant.
Yes, and as you stated in your previous post the responsibility for compliant operation lies with me. Though it is technically no longer a Ramsey designed kit, it is compliant under 15.219 for my use since I am not marketing it.
and:
2. You increased the ability for the final RF stage to put out more RF energy, which cannot be done unless you increase the final RF stage's operating parameters beyond 100mW in by changing its biasing parameters and/or increasing the collector/gate voltage to more than what the kit was originally designed to work under.
The ability of the final RF stage to put out more power can be achieved by optimizing the matching/filtering network which is what I did. This resulted in an increase in the DC power to the final and I had to lower the drain voltage (and current) to bring the operation below 100 mW.
So, perhaps due to my changes to the kit as designed and marketed it can now be considered a "home brew" unit but I fail to see how this is prohibited in the rules.
Using a "stock" kit unmodified does not release the user from compliance with the rules. In fact, if you follow the links in my previous post you will see that according to my measurements the "stock" kit was not compliant with 15.219 at all.
Neil
I actually know a HAM operator who uses a top hat for his part 15 station, no problems.
Putting the antenna next the the antenna with the top hat would cause a directional signal to the direction of the antenna with the top hat. It's not illegal, since it is not attached. there is no reason they would factor what is physically not connected.
The discussions here on the blog/forum have caused my p.o.v. about a few things to take on new beliefs about several things.
I used the word "belief" on purpose, because a belief is not the same thing as definite fact, it is only a personal point of view.
On the subject of "top hats," I "believe" that the vertical measurement of the top hat adds to the 3-meter limit. It's width does not count;
I believe that a non-attached pole or wire placed parallel to the 3-meter vertical is a whole new playground for experimentation. If it can provide a boost or perhaps a desired directionality, I would agree with those who say it will not be a violation because it is un-attached;
I believe a ground lead wire, which is part of the 3-meter limit, is a one-conductor unshielded wire, but a transmission line, a shielded cable intended to deliver RF from the transmitter to a distant antenna is NOT a lead in wire.
Part 15 is my bible (the word bible means book) and we are the "bible" debate society.
Everyone who doesn't agree with me will attract lightning.
Well written Mr. Burns.
Am I correct that the original radio broadcast were HAMs?
Something I very much regret was that I never became one.. My grandfather was a life long ham and he had so much equipment it was unbelievable.. What originally was the outside side porch which ran the entire distance of their house in Bristol Tennessee was at some point was built in and enclosed, and this was his broadcasting room.
Working and active equipment ran the entire length or the room and he spent the greatest percent of his time in there for as far back as I can remember talking to people he had known for years from around the world - although from as far a I know in his whole life he never left the state of Tennessee, except for on road trips back when he was a still a truck driver for Overnight.
But the equipment set up in that room was just the tip of the iceberg. There were also two large metal enclosed sheds out in the yard which had shelves lined up against all four walls and running down the center, literally stacked to the ceilings with equipment, all of which he made a point to insist was all in perfect working order, and then back in the house was a unused bedroom totally flooded with all kinds of indiviual parts, tubes, meters this, that, etc, etc...
He was obsessed. He loved his ham.
When my Dad retired, we all moved to Tennessee, only a few miles away from my grandparents house, so needless to say I was over there quite frequently, and spent considerable time using his equipment and call letters.. it was a major thrill.
Around that time I was maybe about 14 to 16 years old and began taking ham courses which were available locally. My grandmother paid for them. I don't know what it takes to get a HAM license now, but back then (mid 1970's) - the way I recall it, you had to go in stages... the initial permit only allowed you to transmit using morse code, and to get that permit you had to pass test on a novice level of electronics theory and knowledge of certain components, and to be capable to send and read the code at a certain speed.. I had reached the point of acquiring, if I recall correctly, what was called a "novice license", which was the lowest level. But somehow, during jr and high school, my attentions drifted other directions and I never perused HAM further, although I continued semi-frequently talking to my grandads friends around the world on a semi-frequent basis for a few more years.
When I was in Tech school in the Air Force my field was 'Aircraft Electrical Systems Specialist'... Tech school was a cram course in "6 blocks". Each block was a month. Towards the end of my second block one day I got called down to CQ... and I didn't know for what.. I was directed into an office and told to sit down.. I didn't know what was going on and was afraid I was in some kind of trouble. I was 18 years old. The officer sat down behind his desk in front of me, and my sergeant sat down in another chair in the room.
I'll never forget this day, it's one of the stronger memories of my life. My heart was pounding in my head, I think I was shaking a little bit and I felt nauseous. A few days before a few of us had smoked a joint behind one of the dorms and I thought I must have been caught..
The officer was silently looking at some papers on his desk for what was probably only a few seconds, but it felt like ten minutes..
"Airman Powers.. have you had previous training in electronics?
No sir.
Nothing?
No sir (The Ham course several years earlier didn't even come to my mind). Then my Sargent spoke up, "What about in high school, you didn't take any electronic related classes?
No sir.
Airman Powers, said the officer, do you realize you are a full month and a half ahead of anyone else in your class?
No sir.
Do you like your class?
Yes sir
How so?
Well sir, Airman Larry and I get along real well, and I like...
No Airman, not your classmates, your study, do you like it?
Yes sir.
What do you like?
I remember staring at him with my mouth open feeling dumbfounded.
Airman, what interest you most about the class?
Well sir, I like it when we get the paper telling a malfunction and having to use the schematic to find the possible answers.
Why is that Airman?
Again I stared with my mouth open..
I asked you a question Airman.
I don't know sir.
You don't know?
No sir.
He stared back at me and looked pissed, and I knew I had to answer.
Well sir, I guess I like it because it's like a puzzle. I used to like to do the puzzles where you have to convert the numbers to letters to figure out what the answer to the riddle is, and the schematics remind me of that.
It was a totally ridiculous answer, but it was the first thing I could think of to say, and it made the office smile, although I could tell he was trying not to.
Airman Powers, we're making you a yellow rope, you are in charge of or your dorm, from now on you report here at 0500 for the daily duties, it is your responsibility to see to it that they are done, you are not to take part in them, only to direct, do you understand?
Yes sir.
Your excused.
Well... If that isn't drifting off topic, I don't know what is.
The thing is, now days, I couldn't tell you the difference between a diode and a transistor.. it's all gone, been away from it for so long. I once was sharp minded, now I just fumble. It's gone.
Odd thing is, after tech school when I went on to my permanent duty base, I didn't really need to use what I had learned and enjoyed.. the job became more of a "remove and replace" task.. Never actually used a schematic again.
I forgot what this post was supposed to be about.
Evidently it ended up being about me.
I just got carried away
All apologies.
Wow, while I was off in another world, the on-topic discussion has been going on in the present.
Sorry about that guys. Not sure what just happened.
But I'm back now! (awkwardly embarrassed).
Part 15.25 clearly and specifically states that this section applies to a TV interface device and does not include nor mention other kits such as those intended for operation in the AM broadcast band.
OBVIOUSLY! LOL!! Ya it does say "TV Interface Device"...again I believe I stated that in my post...did I not? AHEMM!!!
Regarding my modifications to my Ramsey AM-25 transmitter, your analysis appears to be based on the contents of Part 15.209 in which case doubling the output power and/or changing the antenna could result in non-compliant operation.
WRONG! Attempting to divert the point of someone's clearly written response? Please re-read my post and note how I clearly state "without changing that 100mW maximum input to the final stage" part. That pretty much rules out your assertion of me referencing 209 for that particular case. But I also see where your assuming I meant 209..it was a typo.
The reference to 209, as seen in the OET, as well as in the linked ACTUAL rules I provided, tells you exactly what I meant and had posted in response to this. And that is...once again:
"With the exception of intermittent and periodic transmissions, and biomedical telemetry devices, Part 15 transmitters are not permitted to operate in the TV broadcast bands."
Yep..pretty darn clear right there as to what the reference was for. But I will explain that again. The two sections of the rules, 15.25 and 15.209 contradict each other..and that was the point! It was not using them as reference to what your unit is operating under to be compliant or not! 😀 LOL!!
Though it is technically no longer a Ramsey designed kit, it is compliant under 15.219 for my use since I am not marketing it.
No one said you were intending to market it. Regardless if Ramsey is marketing it or not, or regardless of if you "think" it is a Ramsey design or not, the fact is this...IT IS a Ramsey design. Just read the front plastic plate and your manual. Just because Ramsey is no longer selling this thing or improving its design with newer versions, does not dismiss the fact that it is a Ramsey design! LOL!!! This one really makes me laugh!! Especially when on the PC board itself clearly says "Ramsey AM-25"
So you made a few component changes that helped the poor little thing. Are you saying that these few component changes and adjustments turn this thing into a non-Ramsey design? How do you support that conclusion sir? By a percentage factor of component/circuit changes? Just how much of this thing did you modify anyway? Well in my point of view, in order to "technically" shift it from a Ramsey design over to a new and unique design would require a heck of a lot more than just a couple or three component changes at the output and re-adjusting a bias!! 😀
Ok while I am sitting here holding my gut laughing and keeping from spitting my coffee all over my keyboard....anything else we should cover....oh ya...the modifications themelves.
Her we go....
The ability of the final RF stage to put out more power can be achieved by optimizing the matching/filtering network which is what I did. This resulted in an increase in the DC power to the final and I had to lower the drain voltage (and current) to bring the operation below 100 mW.
Hmm...didn't I state that very same thing that your modifications brought it INTO spec the first time!! This was also going by what you had left out of the first post..you know the part about the doubling of RF output to the antenna.
Provide the particulars of this modification so that it can be validated, duplicated and verified. As I said..for any purpose as far as I am concerned, it's purely curiosity.
I have an original Ramsey AM 25 un-modified and original as original can get as pulled out of the box as well as the original schematic with the original component values.
I was hoping the next reply would have been links to photos and schematics showing these changes you have made.
I, and others I am sure, would love to see these modifications, perhaps we can all learn something from them after all this time Ramsey no longer has been marketing this thing or improving it.
There must be those who use this particular transmitter would like to get the same high efficiency as you are and would highly appreciate it! I know I would if I were using mine. Nothing better than to improve efficiency by simply swapping out a few parts and turning down the bias and get double the RF to the antenna! Every Part 15'er's dream!!
Again don't take all that up there on a personal level. It is not intended out of disrespect..but purely from a technical standpoint. Your not talking to a newbie here, and that goes to anyone who thinks otherwise...OK? I can read schematics and run numbers too...I just need the things that will help me do that, your particular schematic with these changes to compare to a stock unit.
If its too much to ask that's ok. To that end I am glad you found a unique way to improve the thing. But I sure would like to duplicate your results and see for myself! 🙂
RFB
Ahh a little diversion never hurts! Keeps things fresh and hopping!! Like putting on a different record for a dance...mix it up a little! 😉
RFB
a little diversion never hurts
Quite true! I actually believe it to be essential, but I think diverted a bit to extreme in my last post.. just forgot where I was!
Putting the antenna next the the antenna with the top hat would cause a directional signal to the direction of the antenna with the top hat. It's not illegal, since it is not attached. there is no reason they would factor what is physically not connected.
That (concerning the no physical contact) is what I was suspecting Crow, bit as for it acting as a directional signal.. Could that actually potentially increase range in one particular direction? Or does it just decrease the opposite direction?
I used the word "belief" on purpose, because a belief is not the same thing as definite fact, it is only a personal point of view.
On the subject of "top hats," I "believe" that the vertical measurement of the top hat adds to the 3-meter limit. It's width does not count;
I believe that a non-attached pole or wire placed parallel to the 3-meter vertical is a whole new playground for experimentation. If it can provide a boost or perhaps a desired directionality, I would agree with those who say it will not be a violation because it is un-attached;
I believe you are correct Carl.
It has become quiet evident that the existence of Part15 broadcasting is a matter of faith.
Carl is correct. Adding another element, same dimensions etc, but without an electrical connection, and placed at a certain point and distance will cause the omni-pattern of the emitted signal off the transmitting antenna to change.
The "real" stations do exactly that, by using added towers and phasing to change the pattern of the main tower carrying the signal. Sometimes the other towers will also have the signal...often phased differently from the main tower to achieve a particular pattern.
RFB
I'm on a relatively slow netbook at the moment; searches are slow, so I'll get back with the specific regulation sub-parts in about an hour or so.
For now, I can say I've pored over the regs a great deal;, trying to figure out what and why.
There absolutely are regs covering Part 15 kits and homebrew units. One is that kits approved for sale cannot be modified for resale. For example, an SSTRAN's parts you assemble on the board cannot be replaced with parts that reconfigure it and then resold.
You can install and operate as many kits as you like, but you may not do so with an altered kit. My take is that it then becomes a homebrew, and you cannot operate more than 5.
Homebrew units are to be built and operated according to good engineering practices, but you can't operate more than 5 simultaneously.
In the end, the main thrust of what the FCC is doing is to protect legally licensed operations, meaning you can't interfere with your neighbor's radio or TV reception of licensed stations.. Basically you could say all Part 15 regulations are based upon non-interference.
IOW, in any case whatsoever, the operator, not the manufacturer, is responsible. Even if the transmitter is certified, it does not relieve the operator of that responsibility.
And so, IMO, tho' not a lawyer, the FCC has written the regulations to be able to police the appropriate laws deliberately with enough latitude to allow field agents to cite an operation, whether commercial, NPO, or unlicensed, for a violation if they think it is out of compliance.
Do whatever you please, but be aware that interpretation is going to be up to the FCC and its agents, but responsibility for compliance is up to you, the operator.
Seems incongruous, but from all I've read, that's my understanding.
I'll get back in awhile with the collection of regs, which is on the other machine, up at my studio.
Our original exchange here had to do with whether or not the FCC rules forbid changes to AM transmitter kits and then diverged into other technical matters. We have both addressed this topic sufficiently.
I am not trying to claim that my changes to the AM-25 is a new design. Both what I have done and the original Ramsey output circuit are designs which are well known to those practicing the art and both can be found in numerous references I researched while doing this project. The original circuit has been changed and the label on the box is a moot point.
You have asked for my data and I intend to write and post a report when the project is finished. My tests so far indicated a more than doubling of efficiency but I am not prepared to publish my data until I have tried some more changes. At my present pace this may take a week or two.
Neil
Agreeing with Neil Radio8Z on the subject of "changing kits," I will relate my experience with Ramsey AM25. AS IT CAME FROM RAMSEY it was not acceptable for use. When used with the supplied 1000mW wallwart power supply, it was a hum blaster.
The support person at Ramsey was very reasonable and was aware that the power supply was (probably) the source of the hum. So I added a better filtered power supply, and the hum was fixed. But the modulation was noticeably poor, certainly a situation the ordinary user would want to improve. I was able to improve the modulation by replacing the modulation transformer with something different, but then the input to the final stage was above acceptable level, which I think it was to begin with, but it's been a few years.
In any case, my goal was to A.) lower hum; B.) improve modulation, and, C.) meet FCC specs by supplying no more than 100mW to the final amp.
THE ONLY WAY TO ACHIEVE THESE OBJECTIVES WAS BY CHANGING THE KIT.
Therefore, I was obligated to change the kit.
Take another example. The SSTran. As designed, it has no flaws. It does not hum, the modulation is the best, and the output does not exceed 100mW to the final. There is nothing to improve. BUT, it is still my responsibility to check those things and make sure. But in this case, there is no reason to change the kit as designed.
At the end of the day after all the discussions and posturing, if someone hears your signal where they don't want to you'll be shut down even if you are 100% legal.
So, roll the dice, take your chance, try to stay within the rules and have fun because this is really gettin' old.
It's true what's been said by MRAM 1500. Namely, it's political. Holy saints who follow all the rules can be shut down if that's what is decided by titled people with money bag support.
But, if we stop talking about it, part15.us will become obsolete.