[TCML] Is my 10" Tesla Coil Illegal ?

[jimlux]

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.