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Re: [TCML] Is my 10" Tesla Coil Illegal ?



Jim Harvey (UDN) wrote:
Greetings...
I don't post very often but a comment made in this thread said,

========
As far as the RFI, you're probably ok. You're not an "intentional radiator",
and, in fact, you're probably not subject to Part 15 rules at all.
Basically, the folks who are getting interfered with just have to lump it. -
Jim Lux
================

As an amateur radio operator (call sign W7YV), I've had a few opportunities
to defend my own station with regard to interference to others. My hobby is
covered under 47 CFR Part 97. As long as I meet the requirements of being
licensed and do not exceed certain limits, then the folks I might interfere
with "just have to lump it." In reality, I would do what I could to resolve
the problem in the interest of being a good neighbor.
(heh... except if you're operating in a band where hams are a co-primary or a secondary allocation.. 70cm?)

I agree that negotiation and consideration is the best plan, however...

However, the real question is whether a TC is subject to FCC operating restrictions at all. Not everything that happens to emit RF is subject to FCC restrictions on use: examples are arc welders, DC motors with brushes, your vacuum cleaner (a notorious source of conducted RFI), etc. For example, if your car has a lot of ignition noise, to the point of interfering with the radio reception of all the cars around you, I don't believe the FCC can regulate it.

The difference revolves, I think, around whether you are a "incidental" radiator or a "unintended" radiator. (and let's not even get into conducted interference, which is where this thread probably started<grin>).. The FCC doesn't get into conducted emissions for the most part.


I think a TC is what is referred to in the definitions section (15.3) as an
(n) Incidental radiator. A device that generates radio frequency energy
   during the course of its operation although the device is not
   intentionally designed to generate or emit radio frequency energy.
   Examples of incidental radiators are dc motors, mechanical light
   switches, etc.

although some may feel that (z) is more appropriate (depending on whether you think a TC is an RF device or just a HV pulse transformer)
(z) Unintentional radiator. A device that intentionally generates radio
   frequency energy for use within the device, or that sends radio
frequency signals by conduction to associated equipment via connecting wiring, but which is not intended to emit RF energy by radiation or induction.

so then we get to 15.5 "General conditions", which applies either way:
(b) Operation of an intentional, unintentional, or *incidental* radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.

>>> So Jim's (not me, Jim Harvey) comment that the FCC does care is probably right.. even if a TC is an incidental radiator.

However, there's no requirement to meet any particular technical standards (homebuilt provisions in 15.23, for instance) other than "good engineering practice", whatever that might be for tesla coils.

By the way, you also need to look at Part 2, as well as Part 15, because it has some key definitions... Subpart I or Part 2 is the "marketing of RF devices".. which is interesting "2.801 Radio Frequency Device defined": As used in this part, a radiofrequency device is any device which in its operation is capable of emitting radiofrequency energy by radiation, conduction, or other means. Radiofrequency devices include, but are not limited to:
   (a) <snip> (transmitters)
(b) The *incidental*, unintentional and intentional radiators defined in part 15 of this chapter. {Jim added emphasis for incidental}
   (c) <snip>of ISM
   (d) Any part or component thereof which in use emits radiofrequency
 energy by radiation, conduction, or other means.

- so it's pretty clear that from a 2.801 standpoint, TCs are RF Devices.


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