you should consider adding an AGC bypass switch, redesigning the output stage of your iAM for Class E mode (if possible) and adding a +4dbu professional input to your iAM. maybe a redesign of the external ATU to make it more efficient in terms of power transfer to the antenna with maybe an air coil / cap design like the procaster or toroid / cap design like the rangemaster.
maybe one of the forum posters here who is on good terms with dan (calling MRAM) can point him to this post or otherwise suggest these modifications to him.
it should be easy to add +4dbu to the iAM and redesign the ATU, not sure about modifying it for class E maybe Phil B can chime in on that one and better explain modifications for going from the class "C" of the iAM to Class "E" like the amt5k.
these mods would most certainly make an already great little tx system even better.
the iAM now modulates to +125% but it's ATU and Final output stage is still very inefficient like most certified part 15 am transmitters and there is room for improvement there.
maybe since the ATU when attached is considered the Final RF stage the iAM can be configured to bump up to 100mW TPO input to the ATU (final RF Stage) when ATU mode is selected. and when switched to the internal wire antenna can be 100mW input to the final transistor. since when Selected the ATU is the Final it should be legal to put 100mW input to the Final Stage being the ATU not the final transistor in this case. gotta squeeze every little legal drop of Milliwatts we can get out of these things. Efficiency, Efficiency, Efficiency. that is the nam,e of the game. we are limited to 100mW and a 3m antenna and have to get every last drop of efficiency out of the final RF stage and the antenna tuning design.
this already good little transmitter system has some greater potential if radio systems will consider the input from the part 15 community and make suggested modifications if technically and legally possible.
right now i am torn between the iAM because of it's unique system design and fcc certification and my SSTRAN amt5000 because of it's pro inputs, pos. modulation capabilities, and class E output stage coupled to an efficient ATU design but it's only drawback is it is not FCC certified which means more scrutiny from an inspecting agent and some agents take a dim view of kits while others don't.
not sure how denver FCC which i live only 10 minutes drive from would view a kit transmitter.
presently the iAM with it's Class "C" mode applies 60mW to the External ATU connector and the AM double loopstick tuning design of the External ATU is very inefficient. if the mode was changed to class "E" 90mW would amke it to the RF connector and if a Efficient ATU design were employed then more of that power would make it to the 3m antenna which would garner greater range. my tests showed that under similar circumstances the SSTRAN 5k generated a higher F/S than the rangemaster or TH5/ATU combo when mounted in the same circumstances.
i Used a FIM to tune the SSTRAN to resonance though and didn't follow phils instructions on the antenna tuning portion and then proceded to follow phils table to tune for 100mW input. under those conditions the SSTRAN 5k ran rings around competing transmitters that i tested it against for the same installation location.
these are just some thoughts. i am all for pushing the legal/technical limits of part 15 without breaking them and remaining FCC legal.
that leaves us with improving efficiency of the antenna and RF stage.
just imagine an iAM runnning class E mode at +125% using an efficient ATU unit with it's unique system design. it just might blow away all other part 15 certified transmitters out there in terms of performance.
i know in reality i can wish in one hand and crap in the other but i can certainly dream about it.
in terms of audio quality the amt5k, rangemaster rev. b, and the iAM all has similar audo. raw peak F/S (i own a calibrated FIM) the SSTRAN blew them all away.
It is reckless and irresponsible to say
"some agents take a dim view of kits while others don't."
This is an out-of-the-blue unsubstantiable comment which has no basis in fact nor history. It is potentially harmful to kit makers.
It is also misplaced to suggest that "certification" is like a stamp of approval almost bordering on an actual license to broadcast. That's not what certification is in the proper context.
Certification ONLY means that a manufactured pre-built transmitter can be commercially sold by it's maker. Kits do not require being certified and can be legally sold, the governing factor being the Part 15 rules themselves.
JOHN SAID: Agreed. I know of a particular agent who could care less as long as there are no rules violations or complaints of interference to licensed services. This same agent went after a local power company when a case was made that a bad lightning arrestor on a pole was interfering with AM and amateur radio reception. But then again, John could be wrong.
1st, guess you haven't heard of oregon and a FCC guy named NGuyen and 2nd just skip over the entire topic which was about modification suggestions to the iAM / ATU combo.
Modification suggestions are fine and I read them with interest, but couldn't think of anything to add.
I was defensive about Part 15 kits, and am familiar with the peculiar actions taken by agent nguyen, but those had nothing to do with kits so I don't know why he is brought into the conversation.
Doing the best I can.
Hi Guys You guys really need to read this and download it if you haven't already, It's called FCC OET BUlletin no. 63
OFFICE OF ENGINEERING AND TECHNOLOGY FEDERAL COMMUNICATION COMMISSON
UNDERSTANDING THE FCC REGULATIONS FOR LOW-POWER, NON- LICENSED TRANSMITTER
Carl I'm tired of hearing you say that a certified transmitter is only to sell the unit . NO IT ISN'T !!
Here what it says : Although an operator does not have to obtain a license to use a part 15 transmitter, the transmitter itself is required to have an FCC authorization before it can be legally marketed in the united states !!
Here is another reason: This authorization requirement helps ensure that part 15 transmitters comply with the commission's TECHNICAL STANDARDS AND, THUS, ARE CAPABLE OF BEING OPERATED WITH LITTLE POTENTIAL FOR CAUSING INTERFERENCE TO AUTHORIZED RADIO COMMUNICATIONS !!
Here is another reason: For a certified transmitter procedure requires that test be preformed to measure the levels of the radio frequency energy that are radiated by the device into the open air or conducted by the device onto the power lines.
That is word for word in the OET BULLETIN 63
It also Talks about homebrew transmitter, antenna requirements, certification & verification transmitter,labels, modifications, Etc.
Happy reading
Station 8 your candor is good and I appreciate your speaking directly to me in such a way.
I actually don't disagree with you.
But my point is true based on pure law, and your point is true based on that OET Bulletin which is not actually part of the rules and is only a guideline, perhaps not perfectly worded.
It doesn't matter, does it? No matter what people believe, the actual truth never changes, even if we doubt it.
The exception to that is if an FCC agent gets it wrong.
Carl is actually right. You can install a certified transmitter incorrectly (such as having a long ground wire) and that will get you in trouble with the FCC. You can also modify a certified transmitter, with the same results. Certification, if you install within the Part 15 guidelines, should mean that you get no hassle from the FCC. That being said, there is an indivdiual that claims that he installed an unmodified Talking House with a wire antenna and still get an NOUO. In some cases, it appears that it does boil down to the FCC agent.
"Certification, if you install within the Part 15 guidelines, should mean that you get no hassle from the FCC."
Just to note that FCC Part 15 does not contain "guidelines" for unlicensed systems using the AM/FM broadcast bands.
FCC Part 15 specifies the absolute upper limits required for legal performance in those bands.
This is true whether or not a given installation uses transmit hardware that has been certified by the FCC for such applications -- based on the installation configuration of that hardware.
It is the unlicensed operator's responsibility to research/understand the degree of their compliance to FCC Part 15, if they wish to avoid FCC citations.
From a recent thread on this board:
"perhaps common sense goes out the window with Part 15."
For most operators, an accurate understanding of these systems takes more than just common sense.
Rich, don't stop there, you didn't respond to Station8's mention of FCC OET Bulletin 63.
Am I right in saying that such OET bulletins are not part of the Part 15 rules and are, in fact, guidelines of a more general nature?
I like the way you think Blare.
Hi Carl The Fcc OET Bullentin no. 63 does talk about part 15 and where it can be located in the part 15 Rules & regulations law.
So look or print both out : Fcc OET Bullentin no. 63 and do the same with part 15 Rules & regulations law section.
And you will see what i'm talking about.
To me there no guidlines with Fcc it's law and that it !!
I have my own printed ( keep updated when needed in book ) book of the Fcc part 15 rules & regulation law & the Fcc Oet bulletin no. 63 & Fcc public notice as well and have it ready for an Fcc inspection any other documentations i might need as well.
I call it cover your butt!!
First of all, kg8gpd said "... but it's only drawback is it is not FCC certified which means more scrutiny from an inspecting agent and some agents take a dim view of kits while others don't." This is one of those perpetuating urban myths that don't have any factual basis whatsoever.
Here is a response from the FCC in reply to a question about the legality of kits submitted back in 2005 by a manufacturer of certified Part 15 AM transmitters.
(START OF FCC RESPONSE)
”There has been quite a bit of confusion regarding the legality of kits of Part 15 transmitters. I've been coordinating with other staff members and believe that I can clarify our existing policy.
In 1987, the Commission proposed to rewrite its Part 15 regulations. One proposal was to require that all transmitter kits be specifically included under our certification equipment authorization procedure. However, the text that was eventually adopted in 1989 did not contain this language. Rather, it was silent regarding transmitter kits. Further, while Section 15.23 was added to permit home-built devices, kits were specifically excluded from that section.
Section 15.1(b) states that the operation of a transmitter must be in compliance with the Part 15 regulations or the operator must be licensed by the Commission. Section 15.1(c) states that a transmitter must comply with the Part 15 rules, including any requirement for an equipment authorization, in order to be legally operated or marketed. Section 15.201(b) states that a transmitter, other than a home built device (which excludes kits) or certain products detailed in 15.201(a), must be certified prior to marketing. Part 15 also provides a definition of kits under Section 15.3(p).
These regulations, on their face, appear to require that kits be certified by the Commission as a prerequisite to legal marketing and use. However, the fact is that except for kits of TV interface devices and external RF power amplifiers, as described in Sections 2.815, 15.25 and 97.315(b), the Commission has not required kits to be certified as a condition of marketing or operation. This does not mean that the kits are necessarily legitimate. Any assembled kit must comply with the appropriate standards and the marketing of any non-compliant kit would be a violation of our regulations. In addition, we have issued many citations and fines to operators of broadcast frequency transmitters that were assembled from what were supposedly Part 15 compliant kits.
I agree that the regulations themselves could be clearer. Hopefully, we will be able to resolve these discrepancies in our forthcoming clean up of the Part 15 rules.
I'm sorry about the earlier misunderstanding on these issues and hope that the above clarifies matters."
(END OF FCC RESPONSE)
Regarding the statement above: "In addition, we have issued many citations and fines to operators of broadcast frequency transmitters that were assembled from what were supposedly Part 15 compliant kits", I am not aware of ANY FCC citations that have been issued related to the use of US manufactured Part 15 AM transmitter kits. This is not true for FM kits and possibly for AM kits sold by non-US vendors. As of now, all Part 15 AM transmitter kits offered by popular US vendors are in compliance with the Part 15 rules.
Actually, the name "Kit" would be very good if you're having any part 15 children.
But, I wish to follow some of what's been said on the subject of part 15 kits.
PhilB mentioned Part 15.3 (p) "Kit", which says: "Kit, any number of electronic parts, usually provided with a schematic diagram or printed circuit board, which, when assembled in accordance with instructions, results in a device subject to the regulation of this part, even if parts of any type are required to complete assembly."
An important thing about the writing of legal contracts, documents and regulations, is that the "definitions section," which 15.3 is, is a formal and official part of the total document and presents only definitions relevant to the purpose of the document. By giving a formal and legal definition of kit, the Part 15 rules therefore do enable transmitter kits as legal products. Consider the wording, "results in a device subject to the regulation of this part." That statement actually lifts this definition to the status of a green light for transmitter kits.
The opinion expressed here holds true throughout the Part 15 rules, because at no time is it contradicted.