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The AM Transmitter Challenge has arrived
- Thread starter RadioMan203
- Start date
This statement/viewpoint is unwarranted from objective readers of my posts. But certainly Mr. Roos is entitled to his opinion.
I have never claimed/wanted to be considered an "expert," only to compose and illustrate technically accurate posts that might help others -- which posts seldom have been disproven (even by Mr. Roos).
You are correct.
pascoradio,
You have previously described yourself as an EMC specialist, and you indicated in this thread that you have achieved considerable success in your field although, like Fry, you do not possess an engineering degree. I want to say that I have great respect for what you do, and there is no need for you to join in circling the wagons around Fry simply because he is a fellow non-degreed technical specialist.
If you would, please consider Post #32 in this thread, which Mr. Fry was kind enough to supply as an example of his many "paper blizzards." Fry now embraces the term, "paper blizzard." Tell me, John: do you think that Post #32 was intended to inform the reader, or to dazzle and impress him with Fry's brilliance? Do you think anybody actually read Post #32? Would you, yourself, have the cajones to write such a post? I'm sure that you can produce such a post by simply getting a hold of the software (if you haven't already), which in a version suitable for Part 15 AM, can be obtained for free on the Internet.
You have previously described yourself as an EMC specialist, and you indicated in this thread that you have achieved considerable success in your field although, like Fry, you do not possess an engineering degree. I want to say that I have great respect for what you do, and there is no need for you to join in circling the wagons around Fry simply because he is a fellow non-degreed technical specialist.
If you would, please consider Post #32 in this thread, which Mr. Fry was kind enough to supply as an example of his many "paper blizzards." Fry now embraces the term, "paper blizzard." Tell me, John: do you think that Post #32 was intended to inform the reader, or to dazzle and impress him with Fry's brilliance? Do you think anybody actually read Post #32? Would you, yourself, have the cajones to write such a post? I'm sure that you can produce such a post by simply getting a hold of the software (if you haven't already), which in a version suitable for Part 15 AM, can be obtained for free on the Internet.
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Odd that Mr Roos is encouraging a post from pascoradio to include a paper blizzard when Mr Roos apparently dislikes paper blizzards.
Mr. Fry's answer to my previous post puzzles me. It appears to be a non sequitur. Perhaps he doesn't know the meaning of the term "cajones," which is a Spanish word now commonly used in English. Maybe Spanish lingo (lingua) is not very common in his area.
Probably most of the readers of this thread are more interested in posts referring to the purpose of this board, which is not personal attacks.
I know I have come at least close to such attacks lately, but after this response I intend not to reply to posts of Mr Roos that have no technical content.
I know I have come at least close to such attacks lately, but after this response I intend not to reply to posts of Mr Roos that have no technical content.
@Ermi, Thanks for the compliments but they are unnecessary.
Actually I was not circling the wagons but simply injecting humor which I admit is tasteless from time to time. With regard to post #32, it is unclear to me what Rich's intent was as the graphics he posted are familiar to all involved with this thread. So from your point of view I can see your case for grand standing. Now if someone unfamiliar with the expectations of Part 15 whether AM of FM, then I could see his tutorials as being helpful.Probably most would think those graphics were familiar, but then in post # 29 Mr DeFelice wrote (about me): Keep in mind the same attack of credibility comes from the person who penned the ad nauseam statement that a "functionally compliant" Part 15 AM transmitter wouldn't transmit beyond 200 feet, usually accompanied with a barrage of NEC charts and graphs.
I never stated that a Part 15 AM transmitter wouldn't transmit beyond 200 feet, and for accuracy did not want to let DeFelice's comment here stand without correction.
That was the reason for my post #32.
Pascoradio,
Yes, I am familiar with your brand of dry humor, which I had called "European style" in another thread on this site. Of course, you are a true American USN vet, not European at all.
I enjoyed your link to the tutorial explaining Class E tuning on another site, and the good humor you used to deal with the enforcer from the Cult of Phil, who saw your contribution as a possible threat to orthodoxy.
Yes, I am familiar with your brand of dry humor, which I had called "European style" in another thread on this site. Of course, you are a true American USN vet, not European at all.
I enjoyed your link to the tutorial explaining Class E tuning on another site, and the good humor you used to deal with the enforcer from the Cult of Phil, who saw your contribution as a possible threat to orthodoxy.
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Back On Topic
There ARE some valid criticisms to the AM Transmitter Challenge as it stands right now.
The biggest is the fact that different antennas were used with each transmitter. In Part 15 broadcasting systems, having a good ground and antenna system is probably the most important factor in maximizing field strength. I understand that one of the conditions of the test was to use the antennas supplied with the transmitter, but the title of the test (and magazine article) is not Transmitter + Supplied Antenna. The 2 tests involving identical Talking House transmitters with different antennas (wire and ATU/whip) clearly demonstrates that using different antennas on the same transmitter can positively or negatively affect field strength to a large extent.
The major point of contention in the results of the Challenge seems to be relatively poor showing of the AMT5000. The fact that it was tested using its supplied wire antenna certainly raises questions in my mind. It is highly unlikely that anyone going to the trouble of assembling the kit would use that wire antenna for anything other than testing. I doubt very much that the individual who supplied the transmitter uses the wire antenna - the manufacturer recommends using a base loaded whip (i.e., something similar to the ATU/whip of the Talking House).
So while the Challenge was indeed a worthwhile exercise (the testers are to be praised for their hard work), it still leaves open the question as to which transmitter (and transmitter alone) is the most effective at delivering a signal to an antenna. And I suspect that testing each with an identical base loaded whip would have produced better - and different - results.
There ARE some valid criticisms to the AM Transmitter Challenge as it stands right now.
The biggest is the fact that different antennas were used with each transmitter. In Part 15 broadcasting systems, having a good ground and antenna system is probably the most important factor in maximizing field strength. I understand that one of the conditions of the test was to use the antennas supplied with the transmitter, but the title of the test (and magazine article) is not Transmitter + Supplied Antenna. The 2 tests involving identical Talking House transmitters with different antennas (wire and ATU/whip) clearly demonstrates that using different antennas on the same transmitter can positively or negatively affect field strength to a large extent.
The major point of contention in the results of the Challenge seems to be relatively poor showing of the AMT5000. The fact that it was tested using its supplied wire antenna certainly raises questions in my mind. It is highly unlikely that anyone going to the trouble of assembling the kit would use that wire antenna for anything other than testing. I doubt very much that the individual who supplied the transmitter uses the wire antenna - the manufacturer recommends using a base loaded whip (i.e., something similar to the ATU/whip of the Talking House).
So while the Challenge was indeed a worthwhile exercise (the testers are to be praised for their hard work), it still leaves open the question as to which transmitter (and transmitter alone) is the most effective at delivering a signal to an antenna. And I suspect that testing each with an identical base loaded whip would have produced better - and different - results.
Doesn't the AMT5000 have an internal, ferrite-core inductor that can be used to resonate whatever ~3 meter conductor is attached to its r-f output terminal?
In that case the transmit system when using a 3-meter, linear wire antenna would perform almost identically as to when using a 3-meter stainless steel whip, other conditions the same.
The possible difference would relate to the r-f bandwidth of the system -- but measuring such was not one of the objectives of the test, or at least, was not reported.
There seems to be an obsession with the relatively poor showing of the SStran. There may be other factors. What I have not seen is any comments from the person(s) that loaned the SStran. Also, testing the Procaster, Grain and Rangemaster with anything other than the supplied/authorized antenna would have been inappropriate.
The rules for the Challenge were published over a year before the results were published, and people had a problem with them only after The pre-ordained AMT-5000 did not win. The AMT 5000 uses the canonical Class E circuit of the inventors, the Sokals, and has a fairly efficient internal loading coil, and it probably would have won even with the supplied antenna wire if it had actually been tuned for Class E operation. Unfortunately, the instructions do not tell the user how to tune for class E operation.
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The Rangemaster, the winner of the challenge, uses the same iron powder toroid core material as the AMT-5000, but on a smaller core, requiring smaller diameter wire to get the required inductance to tune the antenna. So, the AMT-5000 loading coil should be more efficient than the one in the Rangemaster, because the larger core and larger wire diameter would give higher Q. Also, the Rangemaster has a single-ended class D configuration, while most Class D RF amplifiers are push-pull, resulting in lower efficiency than is obtainable with conventional Class D designs. If the AMT-5000 were actually operating class E, it would definitely have had technical superiority over the Rangemaster. But the manufacturer said a scope "should" not be required for tuning. Unfortunately, if you want class E operation, it is indeed required. It is the trickier tuning requirement of Class E that has kept Class E from overtaking Class D in commercial AM broadcast transmitters.
The point of the challenge was to test each transmitter in the operational configuration as specified by their respective manufacturers. Since the Talking House / i.AM.Radio transmitter accommodates both an external factory-supplied antenna tuning unit as well as an integrated wire lead antenna (like the AMT5000) that transmitter was tested in both operating environments. The Grain GI-100/1000, Ranegmaster as well as the Talking House external ATU all used the same whip antenna. The Chezradio Procaster is supplied with its own antenna, which is an integral part of its FCC certification, and was tested with such. In this case, transmitters were tested in the manner with which they are intended to be operated by the typical end user.
The factory supplied documentation for the AMT5000 makes no mention of any accommodation for any external antenna, nor does the manufacturer produce or supply any external antenna tuning device like the Radio Systems i.AM.Radio. I'm sorry, Geets, but your own feelings hardly stand the test as if the manufacturer doesn't supply the information or the accessory it's simply conjecture on your part to suggest a typical user is going to use anything but the wire lead antenna. In fact, the person who had supplied the loaned AMT5000 for the challenge still had its wire lead antenna attached to the transmitter!
It had been discussed that the ground conductivity in the test area has been documented as being poor, which appears to be the downfall of the AMT5000. Had the manufacturer of the AMT5000 been more forthcoming and supplied ample information on tuning beyond the scope of the information supplied in the accompanying product documentation I would imagine the unit would have proved better. Each manufacturer was contacted, some multiple times, to participate in the challenge. While the manufacturer chose not to supply an evaluation sample of the AMT5000 there was nothing preventing them from supplying any information (tuning, engineering or otherwise) that may have provided a better outcome for the product. Failing any communication from the manufacturer, the supplied documentation was consulted and the outlined procedures adhered to for all tuning and operation. This was the very same methodology used for all the other test specimen.
With staying within the specifications of how the four manufactured transmitters were certified it would be impossible (and meaningless) to use a single antenna for all the tests as you suggest. Each transmitter was configured as it was certified with the exception of the AMT5000, which is exempt from certification being a kit transmitter.
The quote above apparently is the opinion of Mr Roos, but it is unsupported by fact and his due research -- despite any engineering degree(s) and patent(s) he may hold.
Commercial AM broadcast transmitters invented, patented, introduced, and manufactured by Harris Corporation (USA) starting more than 15 years ago use digital techniques with the following proven performance:
Total Power Consumption, Harris DX-10:
- 11.6 kW typical at 10 kW, 0% modulation
- 17.4 kW typical at 10 kW, 100% tone modulation
Note that for the DX-10, the overall a-c input to r-f output efficiency is about 86%, about what would be expected from the r-f amplifier of a practical Class E final r-f stage, alone.
Here is a link to more complete specifications for the Harris DX-series transmitter line:
http://mze.com.ge/uploadfiles/Radio...ansmitter Family/DX AM Transmitter Family.pdf
Appealing to common sense, aren't ALL antennas used with "Part 15 AM" transmitters installed external to such transmitters?
No "external antenna tuning device" is needed to Z-match a ~3-m linear conductor connected at/to the r-f output connector of a Part 15 AM transmitter containing an internal "tuning device" designed for that purpose.
Is such a tuning device NOT included in the AMT5000?
There would be NO relative difference in the affect of ground conductivity on the fields radiated by, and (accurately) measured for any of the systems of this "Challenge."
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Hopefully someone will relay these comments to Mr. DeFelice (RadioCityBill), who IIRC has stated that he has arranged not to directly receive anything I post.
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