No, not the bible, I am talking about Part 15 myths that won't die.
There are two such myths that I encounter all the time on all the Part 15 forums, and chances are you know a few more.
One myth is the notion that certified transmitters give the user some kind of special protection. That's FALSE. The certification only exists to show that a factory-built transmitter has been FCC Certified so that it can be sold legally by the manufacturer. That's ALL the certification means. That transmitter will STILL be evaluated the same as any other for compliance with Part 15.219, except for that unexplained inspector in Oregon who goes only by 15.209.
My second myth is "underground radials will not radiate." The true answer is IT DEPENDS. If only a single radial wire is connected from transmitter ground and run underground for whatever distance, IT WILL ADD RADIATION TO THE OVERALL LENGTH INCLUDING THE ANTENNA! The minimum proper radial installation must consist of TWO wires of equal length from transmitter ground and reaching in opposite directions in a straight line, in which case the two branches of the radial achieve 100% phase cancelation of any added radiation. No matter how many radials are added, there must be an even number, otherwise the odd numbered radial WILL add radiation.
There is a third myth that has been invented by posters on a smaller website as part of a character attack against a popular transmitter maker, claiming that AM transmitter kits are not allowed under the Part 15 rules. That, simply, is a lie.
Know any more Part 15 myths?
Yep - with a quick note that the manufacturers of the certified units will *sometimes* go to bat for you if you are running the tx in compliance. If you are running your tx outside of complaince, you are on your own. SOME manufacturers will go to work on your behalf if you are running in compliance, and are still told you can't broadcast - this would make them less likely to be able to sell the unit if they didn't.
You are technically right, Carl, but the reality is that if you are running a certified transmitter and have it installed in compliance with Part 15 rules, you will likely receive far less scrutiny than a non certified one, kit or otherwise.
Hello Arisan. You are very definite by saying "the reality is," but with my different point of view the most I would say is that it's a "possible reality" that a compliant certified transmitter will suade the inspectors to go lighter.
Home made (kit) transmitters are also allowed by Part 15 Rules, and under the best circumstances I would expect the inspector to check ANY part 15 transmitter against 15.219 and if that fails, against 15.209.
But I think I see another aspect of the "myth" that I hadn't considered...
It is my opinion that the antenna and other parts that form the basis of gaining the Certification is only of significance within the compliance engineering test process, and that the end-user is free to use ANY Part 15 compliant antennas and grounds without penalty.
I think the word "compliant" has been used to mean two different and separate things.
From what I've seen, most of the issues on Part 15 AM are the result of non compliant antenna/ground systems and NOT the transmitter (unless, of course, you're using watts instead of milliwatts).
While the FCC (and Industry Canada) can inspect ANY station, from what I've seen they generally won't unless 1) By measuring your field strength, it's obvious that you're not complying with Part 15 rules or 2) By looking at your antenna/ground system, it's obvious that you're not complying.
If you get by those 2, and you're using a certified transmitter, I don't think that the FCC would give you another look. They probably wouldn't even if it wasn't certified, however, depending on the inspector, the odds are greater that they might want to look deeper. But I wouldn't bet on it. It would be like beating a dead horse.
As it sounds like those guys are doing on that other Forum (wherever it is).
First lets draw a big distinction between AM and FM transmitters. FM draws most of the FCC attention. Historically, there have been many non-certified FM transmitters on the market, both manufactured and kits, that are capable of violating the rules. The FCC crackdown on FM has changed this picture somewhat and many of the FM transmitters have been dumbed down to produce the expected 200 to 500 ft range.
On this board we see very little discussion of FM transmitters and a lot of discussion about AM transmitters. Yet, we still see the typical blanket statement that you will be "safer" with a certified transmitter. Different people seem to repeat this over and over as if it somehow became a fact just because it was repeated over and over. In fact, there is no evidence that using an uncertified transmitter has contributed to any of the FCC NOUOs. The only evidence related to "certification" has been entirely to the contrary. By secondary sources of information posted on forums, we know that NOUOs have been issued to Rangemaster and TH users, both are certified. Nothing has ever been posted linking an NOUO to use of an uncertified transmitter other than obvious pirate operations.
The very, very few number of non-pirate NOUOs for AM have been issued to people who violate the antenna and ground lead length rule (visible by the FCC from the street), not because they used an non-certified transmitter. These are the unlucky users. Many people operate with antenna/ground lengths far in excess of the rules and slide by under the radar for years.
I know of no serious AM transmitter kits on the market that violate the only part of the rules that pertain to the transmitter: 100 mW power and spurious emissions leas than 20 dB. It's pretty hard to get that wrong.
So, the myth about being safer with a certified AM transmitter is confirmed by the total lack of evidence to the contrary. Why do we still hear this myth repeated over and over?
...So, the myth about being safer with a certified AM transmitter is confirmed by the total lack of evidence to the contrary. Why do we still hear this myth repeated over and over?
Probably for three reasons.
- It tends to improve the sales of the manufacturers of those certified transmitters.
- The subject was not well researched/documented.
- "People" want it to be true.
Maybe there are part15ers out there, more than on this board, that have had the FCC come a knocking, and nothing ever became of it because the user of the certified transmitter showed the FCC the certification paperwork for the tx?
NOTE: This is as much the same speculation as above.