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I’m became curious about something as I was observing the ongoing discussion in the “CB whip atop another antenna thread”.. and I almost asked it right then and there, but suppose it deters a bit from topic, so instead started a new thread..
But anyway, in that thread, while the subject of top hats was brought up it reminded me of something I had pondered on previously..In the case of using a certified transmitter like the Rangemaster, one could not incorporate a Top Hat into the design because it would void the certification – correct?
But what if a pole, or some such structure were to be erected parallel to the transmitter and it’s antenna in such a way that you could attach to that parallel pole, and extend from it a Top Hat directly over the top of the antenna and just about an inch or less above it..
(I hope I’m conveying this clearly)Would this still increase the performance of of the antenna?
Would it make much difference. Would it be legal?
Or is this just a crazy idea?
Total posts : 45366In the case of using a certified transmitter like the Rangemaster, one could not incorporate a Top Hat into the design because it would void the certification – correct?
If I understand the certification correctly then the answer is yes. A part 15 intentional radiator is certified with a particular antenna which is either permanetly attached or uses a unique connector to assure that only that antenna is used.
Regarding your suggestion about a nearby conductor with a top hat functioning as an antenna element, a conductor near a radiating antenna will pick up a signal by coupling and radiate its own signal possibly enhancing the total radiation from the system. It is only speculation, but an inspector would probably see through this and consider the extra element(s) as part of the antenna.
My experiments with a coil loaded antenna system yielded data which shows a significant effect on the antenna tuning caused by a nearby wire (4 inches distant and parallel to the radiating element). I did not measure the field strength to compare this situation with the one with the wire removed but since the parallel wire affected the tuning in a major way it is logical to conclude that RF energy was being coupled into the passive conductor and radiated by this conductor.
Neil
Total posts : 45366The diameter of the top hat may be added to the 3 m length budget, but I have not seen any FCC ruling about top hats.
Using a larger diameter antenna (maybe up to 3″) for the Rangemaster should improve performance, but also void the certification. It may not matter that the certification is voided if the Section 15.219 requirements are met. Only certified transmitters (not in kit form) can be sold, but the FCC does not seem to be concerned about the use of uncertified 15.219 transmitters provided that the technical requirements are met.
Total posts : 45366It is only speculation, but an inspector would probably see through this and consider the extra element(s) as part of the antenna.
Neil, even though it was making absolutely no physical contact with it?
It may not matter that the certification is voided if the Section 15.219 requirements are met. …
That’s a curious statement Ermi.. It stunned and puzzled me a tad, but I suppose it is accurate!
I never considered the the fact that voiding the certification does not mean it makes it any less legal, but somehow the thought doing that still bothers me. — Throws me off a little. hmmm.. curious.
Total posts : 45366but the FCC does not seem to be concerned about the use of uncertified 15.219 transmitters provided that the technical requirements are met.
Exactly correct. There was a time when people playing with radio actually built their transmitters…part of the hobby…actually it was once the core of the hobby. You are allowed up to 5 units of your own making and they cannot be sold unless you get them certified.
This is why kits that require assembly and do not have any certification can be sold. But there are stipulations to that. You cannot modify them that alters their RF output, you cannot use parts that were not supplied in the kit, and the kit must be designed to meet those specifications.
Most kits abide by those stipulations, therefore are perfectly legal to sell and use.
Reputable kit manufacturers will ensure their kits meet the specifications. Take SSTran for example, Ramsey among a few others. Then you have those less than reputable places that spit out stuff that no doubt would raise an eyebrow at the FCC.
As to the “passive” antenna question, it works much like how two tuning forks work. Strike one and bring the other close to the vibrating one and the two will begin to resonate. With a certain configuration and placing of the passive element, it can function as a pattern director, ie make your signal more directive this way instead of that way.
RFB
Total posts : 45366Neil, even though it was making absolutely no physical contact with it?
Yes. In fact I saw through this and removed the parallel wire (which was left over from another experiment) so there would be no question about the antenna length.
Question for RFB:
You cannot modify them that alters their RF output, you cannot use parts that were not supplied in the kit, and the kit must be designed to meet those specifications.I am not aware of anything in the part 15 rules which prohibits the modification of a kit (other than a “TV interface device”). Can you enlighten me?
You and others might be interested in this:
http://www.part15.us/node/938
and this:
http://www.part15.us/node/2669I have modified my Ramsey AM-25 to meet the 100 mW DC input rule. Should I have not done so?
Neil
Total posts : 45366I have modified my Ramsey AM-25 to meet the 100 mW DC input rule. Should I have not done so?
Your modification of the AM-25 so that it meets the 15.209 spec is perfectly fine. The modification did not jack up the power or cause it to do the hokey pokey dance all over the spectrum.
There is somewhere on the net a site showing modifications to one of those where several key components, mostly the audio circuitry and output circuitry that made it go way beyond Part 15.209 specs. The person who did the modifications claims they were done so that it could be used for a Carrier Current configuration and has the unit inside a bigger cabinet containing a tuning network for that purpose. If this is true who knows.
Yes there is not a specific rule regarding kits and using parts that did not come in the kit. However if you have ever built one and carefully read the manufacturer’s notes and warnings, you will find most of them do state that you should use the parts supplied with the kit.
However one tidbit rule that does point to that is the rule specifying kits use a specific type of antenna and connector. That my friend is saying “you must use the antenna and connector supplied with the kit”. It also means you cannot modify it with some off the shelf connector and antenna. It is safe to apply that same aspect to ALL of the components that came in the kit.
Prior to the revision of the rules in 92, there were specifics written down in the rules that clearly stated kits must be assembled using the supplied parts.
The reason for that is because even today, kits are designed with specific types of components to make them operate like they should operate. Using different components can cause the kit to operate incorrectly, such as throw too much power or put spurious on the band or some other thing.
But the bottom line with any kit, certified or otherwise..is the one thing that ALL of them say in their manuals. “You are responsible for the proper assembly/operation of this kit and to comply with all federal regulations”.
RFB
Total posts : 45366================= BREAK ====================
I read your-alls post in this thread a couple times. and I’m hesitant to say this because I don’t want it to be taken wrong. But if I may summarize what I’m hearing.. and you tell me if I’m hearing this right..
Rich:
Can I put this thing here next to my transmitter to improve it’s performance?Neil:
Positioning a radiator that is not making any physical contact, but is in close proximity to the transmitter antenna would likely be deemed to as exceeding the 3 meter rule, thus it is illegal.Ermi:
Agreed; a top hat positioned separately on its own with no connection might be considered illegal, but it probably would be legal to attach a 3″ thick pole in place of your antenna, but you lose certification.RFB:
You’re precisely right! The FCC doesn’t care if you modify a certified unit as long as you adhere to the 15.219 requirements. But whatever you do don’t go altering the construction of a kit, that’s against the law. But as for the late certified unit; putting something close to it creates an entirely different situation, so…Neil:
So… don’t put nothing near it! I certainly wouldn’t do such a thing. But I did modify some kits.. You mean I shouldn’t have done that?RFB:
Oh, that’s not what I meant, you were perfectly fine to modify those kits, there’s nothing that says you can’t.. that is unless you read between the lines of the manuals they provide.Rich:
…Huh?
Total posts : 45366RFB:
You’re precisely right! The FCC doesn’t care if you modify a certified unit as long as you adhere to the 15.219 requirements. But whatever you do don’t go altering the construction of a kit, that’s against the law. But as for the late certified unit; putting something close to it creates an entirely different situation, so…
RFB:
Oh, that’s not what I meant, you were perfectly fine to modify those kits, there’s nothing that says you can’t.. that is unless you read between the lines of the manuals they provide.NO, the FCC DOES care about modifying kits that have original parts included in them. What they do not want you to do is use parts that are outside of the design factors of the kit…ie use a bigger transistor on the output of a transmitter that although will work with 9 volts and meet the specs, you could easily feed it with 15 volts and jack up the power by simply supplying that with more B+.
Now as to your modification to the Ramsey, yes you misunderstood what I meant. Your modification did NOT change it so radically that you made the thing go beyond its design parameters. You actually brought it INTO specifications for 15.219. There is a HUGE difference between modifying a kit to BRING IT INTO FCC specs and modifying a kit to take it OUTSIDE of both its design parameters as well as 15.219.
Modifying a kit using components of the same type, not necessarily the same value which improves the unit’s performance to MEET specification of 15.219 again is different from using parts of the same or different value but allow the unit to boldly go where no TX should go is a no-no.
Example….lets say the output of the transmitter uses a small signal 2n3904 transistor and it has 9 volts on the collector for B+ The design of the TX used the 2n3904 because the characteristics of that transistor help keep the TX from operating outside of 15.219. But you then replace with with a transistor that can take 15 volts B+ and has heavier characteristics which can handle the increased B+ voltage, this will obviously increase the TX output..and take it outside of 15.219.
Hope that was some help in clarification…at least for my part in answering your initial question. 🙂
RFB
Total posts : 45366More Mind Mashing Mods Means Mania.. Try saying that three times fast – or even once!
Hope that was some help in clarification…at least for my part in answering your initial question. 🙂
Well it doesn’t answer my question, but I hear what you’re saying.
Glad you took it in the jest it was intended RF, I was worried the sarcasimic wit could ruffle a feather or two.
Total posts : 45366Rich, if I have not made it clear that what I posted is my opinion and is not literally in the rules then allow me to try again. Ultimately, the compliance with the rules regarding the antenna system is the decision of the FCC inspector if it comes to that. A conductor in proximity to an active antenna receives RF energy by capacitive and inductive coupling which both depend upon the distance of separation. Whether this would violate the rules is a subjective judgment call and I have chosen to avoid this question by removing the parallel wire I mentioned earlier. This is my decision for my installation and it is not based upon any enumerated rule. You are free to do what you want.
RFB, I ask again where in the rules is modification of a kit prohibited? I am trying not to confuse kit modification with operating outside the rules since these are two different issues. There is nothing I am aware of which prohibits such modifications regardless of the extent of the changes. There is something wrong when changes result in non-compliant operation and we seem to agree on this point. The non-compliant operation is prohibited by the rules but the means by which it is done are not. It is the outcome which counts, not the method.
Here’s an example. I performed modifications to my Ramsey which doubled the efficiency of the final output stage and it is operating at less than 100 mW power input yet the RF output power to the antenna is doubled. The out of band emissions are well below the limits stated in the rules. I see no compliance problem with this and will appreciate your input if you do.
Neil
Total posts : 45366RFB, I ask again where in the rules is modification of a kit prohibited?
THE FOLLOWING IS NOT MEANT TO BE ANY SORT OF POKE, JAB, DISRESPECT, OR DEMEANING TO ANYONE. I AM SIMPLY ANSWERING YOUR QUESTION TO THE BEST OF MY KNOWLEDGE, EXPERIENCE AND COMMON SENSE AS A RADIO ENGINEER/HOBBY ENTHUSIAST!!! Just want that very clear before more misinterpretations start flying in this place!
I believe I answered the question already. Obviously it appears your referencing the OET bulletin 63, which is NOT the be all end all of the rules, it is a publication to provide a general “layman” level explanation to the rules, in fact it says that within the OET 63 bulletin on the onset within the Introduction….as follows:
“This bulletin is intended to provide a general understanding of the FCC’s regulations and policies applying to products using low-power transmitters. It reflects the current text and interpretations of
the FCC’s regulations. More detailed information is contained in the regulations themselves, which can be found in Part 15 of Title 47 of the Code of Federal Regulations. This bulletin does not replace
or supersede those regulations.”Ok now that we clearly identified that OET 63 is NOT the be all end all of the actual rules…lets proceed.
The FCC, as well as the kit manufacturers want you to build your kit using the supplied parts. Modifying it with components which would allow the unit to operate beyond its design parameters would make the unit non-compliant or void a certification. Are you with me so far?
If not…read on…
Taken from the always mistaken for the real letter of rules, OET 63, which in this case I am going to use an excerpt from that OET 63 publication which states:
Changing the antenna on a transmitter can significantly increase, or decrease, the strength of the signal that is ultimately transmitted. Except for cable locating equipment, the standards in Part 15 are not based solely on output power but also take into account the antenna characteristics. Thus, a low power transmitter that complies with the technical standards in Part 15 with a particular antenna attached can exceed the Part 15 standards if a different antenna is attached. Should this happen it could pose a serious interference problem to authorized radio communications such as emergency, broadcast and air-traffic control communications.
In order to prevent such interference problems, each Part 15 transmitter must be designed to ensure that no type of antenna can be used with it other than the one used to demonstrate compliance with the technical standards. This means that Part 15 transmitters must have permanently attached antennas, or detachable antennas with unique connectors. A “unique connector” is one that is not of a standard type found in electronic supply stores. Section 15.203
It is recognized that suppliers of Part 15 transmitters often want their customers to be able to replace an antenna if it should break. With this in mind, Part 15 allows transmitters to be designed so that the user can replace a broken antenna. When this is done, the replacement antenna must be electrically identical to the antenna that was used to obtain FCC authorization for the transmitter. The replacement antenna also must include the unique connector described above to ensure it is used with the proper transmitter.
OK…now this is talking about an antenna and connector supplied with the kit. Right? With me so far?
What exactly does it mean by saying:
“each Part 15 transmitter must be designed to ensure that no type of antenna can be used with it other than the one used to demonstrate compliance with the technical standards.It means that the kit must be designed so that it takes only ONE type of connector for the antenna and the antenna must be one that will work with that special kind of antenna connector. Pretty straight forward right?
In the basic sense, it means USE THE SUPPLIED ANTENNA AND CONNECTOR!!
With me so far?
This is a FIRST good indication that the FCC wants you to use supplied parts that come with your kit.
Now in 15.25…
FCC Part 15.25 found at this link:
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=867a520dbbf52369e0b5f4faa48775a1&rgn=div8&view=text&node=47:1.0.1.1.14.1.242.13&idno=47We see it says “TV Interface device”. What does that mean? TV Interface device?….a video/audio to RF converter?…ahh….must be..right? Hmm….well what about….15.209 and OET 63?
Which OET 63 says:
“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.”A contradiction between 15.25 and 15.209 perhaps? A mistake perhaps? With the clutter of rules crammed into the Part 15 section alone….possibly a mistake..but highly unlikely.
So for the sake of argument….referencing 15.25 and 15.209, we should take into account that although 15.25 says a “TV Interface Device”, it should not be taken literally that the FCC is only talking about an audio/video RF converter, which by the way is normally used via a coax cable connected directly between the audio/video RF converter output and the TV receiver RF input connector and not running through an intentional radiator!! Unless the unit is designed with a “whip”, which by the way COMES WITH the assembled OR kit unit, most of those types operate in the 900Mhz band or higher in Part 15, which are NOT within the TV broadcast frequencies at all.
Now…again for the sake of argument, and to have a good margin of safe assumption in interpreting their rules mess, it is clear that the FCC wants you to use the supplied parts that came with your kits and to not use parts that did not come with the kit which would make the kit operate outside of its design parameters and/or make the kit operate outside of its authorization..ie emission limits, spectral purities, bandwidth utilization, frequency stability, interference limits and so on, for the given section of the rules authorizing its use..in this case…Part 15.
With me so far?
Let me throw this out here, as a side note, as I did in email conversation with a former member of this board, which the conversations continues to this day and has been over the last week or so…
Do we, meaning us RADIO people with adequate level of knowledge to know about transmitters, antennas, receivers, components etc, need the FCC to actually spell it out as A, B, C….and connect every dot and dash for us “RADIO” people to know exactly what they are saying in these rules?
Are we saying that although we are smart and know the difference between what an A is, what a B is, and what a C is, that we cannot fully comprehend what they mean in these rules unless they spell it out for us at pre-entry beginner radio person or average joe public knows nothing about anything about radio layman level other than knows how to turn it on and tune in?
Do we need to go back to elementary school and learn our ABC’s again?
With me so far?
Now..on to your modifications…and it is interesting that in the first post you left out some crucial information and now included it in your later post…which does change things and raises concern that you are currently operating in violation…and I will explain why I am saying that.
Here’s an example. I performed modifications to my Ramsey which doubled the efficiency of the final output stage and it is operating at less than 100 mW power input yet the RF output power to the antenna is doubled. The out of band emissions are well below the limits stated in the rules. I see no compliance problem with this and will appreciate your input if you do.
Now there is only one of two ways to “double” the RF output power to your antenna from the transmitter…and it wont be due to increasing efficiency of the output circuit without changing out components that did not come supplied with the kit. Only one of or combination of the following two ways this doubling of efficiency and doubling of RF output to the antenna can take place without the use of an external piece of equipment such as a linear or larger B+ voltage source…
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.
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.
Claiming that you “doubled” the RF output to the antenna and still operating at 100mW final stage limits is pretty bold and leaves you wide open to being suspect of possible violation without showing us your data, measurements, photos of these modifications, any evidence that can support your claim that you have this Ramsey AM 25 still operating within the Part 15.209 limits.
Now, have you done any field strength measurements off that antenna at the given distance per your frequency of operation for intentional radiator?
If so, what type of measuring equipment and antenna used to make the measurement, and is this verified by reasonable comparison to a calibrated measuring equipment?I would be most interested in seeing these modifications, both in picture form and schematic form, as well as seeing field strength measurements…even for just curiosity sake, which it would be..just out of curiosity.
After all….it will be YOU that will have to prove to the inspecting FCC agent that your modifications did not take your Part 15.209 setup beyond the authorization limits of 15.209. When they decide to field strength test your setup and you claim you doubled RF output to the antenna…..well we will leave it at that and let the chips fall where they may.
It is the outcome which counts, not the method.
Not so simple as that. So what is the outcome keeping that unit in compliance when the outcome is doubled? And despite your quote up there, it took a method to obtain that doubling in efficiency and RF output. Not to be demeaning or anything, but your saying two different and contradicting things there within your entire post with that last statement.
RFB
Total posts : 45366I’d like to make a side comment/question not directly related to your subject:
HOW DOES THIS MAKE SENSE?:
….This means that Part 15 transmitters must have permanently attached antennas, or detachable antennas with unique connectors. A “unique connector” is one that is not of a standard type found in electronic supply stores. Section 15.203
It is recognized that suppliers of Part 15 transmitters often want their customers to be able to replace an antenna if it should break. With this in mind, Part 15 allows transmitters to be designed so that the user can replace a broken antenna. When this is done, the replacement antenna must be electrically identical to the antenna that was used to obtain FCC authorization for the transmitter. The replacement antenna also must include the unique connector described above to ensure it is used with the proper transmitter….I’ve noted this quote several times before, and everytime it sounds like a contradiction to me.. in relation at least to the Rangemaster.
1. A “unique connector” is one that is not of a standard type found in electronic supply stores.
The Rangemaster most absolutely utilizes a standard whip CB connector commonly found in electronic supply stores2. Part 15 allows transmitters to be designed so that the user can replace a broken antenna. When this is done, the replacement antenna must be electrically identical to the antenna that was used to obtain FCC authorization.
Ok, makes sense in itself.3. The replacement antenna also must include the unique connector described above to ensure it is used with the proper transmitter… There’s that contradiction again!
The certified Rangemaster certainly DOES utilize a standard connector, and was certified with use of one, and obviously DOES NOT utilize a “unique connector” which is not commonly found in electronic stores…
So how is the quoted statements accurate? – They’re not!
Total posts : 45366I have to agree Rich. The rules are certainly not clear at all, and is the very reason why many of us, even veteran engineers always go back and keep looking at those same confusing rules to try and dig out some sense of it all.
But in the case of the “permanently attached antenna” issue, in my view I believe they mean a device that has one already attached from the factory and not meaning devices assembled at home where not only the supplied antenna and connector can be installed, but a different one as well.
As to the Rangemaster, and even Procaster, which both do use a “common” type of connection, it is easy to substitute the antenna on both, in whereas the Rangemaster, you simply screw on a different antenna if it can properly fit the threads of the stud, and in the Procaster case, simply loosen the two nuts holding the aluminum rod in place, and replace the aluminum rod with another, re-tighten the nuts. Both of these units carry the FCC certification.
In my opinion, the meaning of the rules here is saying you cannot unscrew or unbolt the supplied rod or whip with one that lets these units operate beyond their certification…ie put a longer whip or rod in place of the original one.
This is why I was saying that as radio people with radio engineering knowledge MUST use our knowledge with a dose of common sense in these matters in order to be within the compliance of the rules as written.
We all know that during the revision, they left out a lot of the revisions. Ironic to say the least..and is why I believe it was done on purpose to cause all this confusion, which in turn makes it quite easy for the FCC to readily tag a setup as being non-compliant, even though the operator/owner took great steps of good engineering practices to maintain compliance. Sort of having a dead bolt lock on a door with no dead bolt locking element, yet it is called a dead bolt lock.
In all aspects, we must take into account that the FCC is letting us radio engineer types use our better judgments and knowledge to know what is right and what is wrong. They are saying that we should know better and do not have to have our hands held all the time. If we do not use our better judgment and knowledge to know the difference of right and wrong..then they come along and show you the difference with the NOUO or NAL’s.
What do you think?
RFB
Total posts : 45366We all know that during the revision, they left out a lot of the revisions. Ironic to say the least..and is why I believe it was done on purpose to cause all this confusion
I’ve heard several make that comment…. But I’ve always tended to doubt that. It just seems unlikely to me that the Part15 rules and regs were intentionally written to be contradictory, vaque, and confusing.
I’m more inclined to believe they just evolved that way.I assume that a basic and clear set of rules were put to paper when part 15 transmitting originated, which did make perfect sense.
And then through the years were repeatedly amended so many times to cover various new situations and diversities of applicable uses, that it ended up as a big mesh-mash dumped into a single pot that would have been better served out in separate portions.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.
We as broadcasters are the genie that came out of the bottle.. and you cant put it back in.. just can’t fit. And they don’t know what to do with us.
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