When it is legal to modify a part 15 device?

[drdiesel1]

I thought there were provisions allowing modification if certain rules were followed, such as max EIRP. As you can see below section 15.203 does list a few Or's on antenna modifications.

Can anyone cite regulation that permits antenna modification on the 2.4ghz band? Can a device originally sold as a part 15 be operated by anyone on part 97?

Section 15.203 Antenna requirement.

An intentional radiator shall be designed to ensure that no antenna other than that furnished by the responsible party shall be used with the device. The use of a permanently attached antenna or of an antenna that uses a unique coupling to the intentional radiator shall be considered sufficient to comply with the provisions of this Section. The manufacturer may design the unit so that a broken antenna can be replaced by the user, but the use of a standard antenna jack or electrical connector is prohibited. This requirement does not apply to carrier current devices or to devices operated under the provisions of Sections 15.211, 15.213, 15.217, 15.219, or 15.221. Further, this requirement does not apply to intentional radiators that must be professionally installed, such as perimeter protection systems and some field disturbance sensors, or to other intentional radiators which, in accordance with Section 15.31(d), must be measured at the installation site. However, the installer shall be responsible for ensuring that the proper antenna is employed so that the limits in this Part are not exceeded.

 

[N4DES]

I don't think that there are a specific regulation that allows for antenna modifications on lets say a 2.4GHz router, which is why the manufacturers designed reverse SMA's on the units that satisfied the FCC antenna requirement. But as we all know there are tons of aftermarket 2.4GHz antennas that are on the market today. YMMV on the legality of use as the manufacturer waives the liability and puts the responsibility totally on the seller and end user.

On your second question, as long as the Part15 device operates in the Part97 spectrum it can be utilized and modified as long as it fits the Part 97 rules to include no encryption. As an example, if you are using a modified wifi router for Part 97 you cannot legally utilize the provided encryption and must operate it in the clear. We have had discussions locally on this between amateurs that use their router in a Part 15 application but blast their callsign as the SSID and use encryption. The FCC or an OO doesn't know really what the device is really being used for, so a notification could come in the mail requesting clarification as to why a wifi router is operating in the Part97 spectrum, transmitting a call sign, and is utilizing encryption.

 

[zz0468]

I thought there were provisions allowing modification if certain rules were followed, such as max EIRP.

No. But some radios are certified for use on any antenna, provided that EIRP guidelines are followed. Other radios are required to use the manufacturer supplied antenna.

As you can see below section 15.203 does list a few Or's on antenna modifications.

That is not a "modification".

Can anyone cite regulation that permits antenna modification on the 2.4ghz band?

No, because no such regulation exists. Are you confusing this with Part 15.407 which includes EIRP regulations, and how to calculate compliance?

Can a device originally sold as a part 15 be operated by anyone on part 97?

By "anyone"? No. It would have to be a licensed amateur. But it IS legal to modify a Part 15 device, and operate it under Part 97, so long as Part 97 rules are adhered to. This would include the type of traffic it carries. A wireless router with additional power, and a large directional antenna using SSID as a form of identification would be legal, so long as it's not carrying general internet traffic. If it's restricted to carrying, say, IRLP link traffic, then that would be fine.

 

[drdiesel1]

Guys, thanks for the replies.

 

[kb2vxa]

Why complicate the issue? Here's the short and sweet answer.

"Can a device originally sold as a part 15 be operated by anyone on part 97?"

Yes. Just to make short a little longer, Amateur equipment needs no FCC certification so as long as a transmitter meets spectral purity standards you're good to go as long as you're licensed.

 

[zz0468]

Why complicate the issue? Here's the short and sweet answer.

Short and sweet... you left out "wrong". The OP's question asked if ANYONE can operate a Part 15 radio under Part 97. The accurate answer is no. Only a licensed amateur can do that.

 

[drdiesel1]

Essentially correct. Section 15.203 states that you must follow one of the three options and gives an out under the listed sections numbers.

This requirement does not apply to carrier current devices or to devices operated under the provisions of 
Sections 15.211, 15.213, 15.217, 15.219, or 15.221. Further, this requirement does not apply to intentional 
radiators that must be professionally installed, such as perimeter protection systems and some field 
disturbance sensors, or to other intentional radiators which, in accordance with Section 15.31(d), must be 
measured at the installation site. However, the installer shall be responsible for ensuring that the proper 
antenna is employed so that the limits in this Part are not exceeded.

I am still not completely clear to be honest. If professionally installed, whatever that means, can it be modified and used under part 15?

As you can see carrier current devices and sections 15.211, 15.213, 15.217, 15.219, or 15.221 are not bound by this rule.

I am guessing what they truely mean is if it came with an attached antenna, your stuck with it, under part 15! If it has a normal antenna jack your bound by "professional installation", even though a reverse SMA is now pretty common.

Clear as mud.

 

[zz0468]

I am guessing what they truely mean is if it came with an attached antenna, your stuck with it, under part 15!

Yes, that's what it means.

If it has a normal antenna jack your bound by "professional installation", even though a reverse SMA is now pretty common.

What they mean is that some devices are plug and play, designed for consumer use. Others require "installation", as in climb a tower, hand a dish, bolt the radio into a rack, etc.

In that type of equipment, the EIRP requirements need to be determined and complied with.

Clear as mud.

Yep.

So, maybe if you were to state what you're actually looking for here, we could cut to the chase. Picking and choosing an antenna for a device that has an N connector on it is NOT a modification. Pulling off the built in 1/4 whip and replacing it with an N connector is.

If you actually modify something, it's no longer Part 15 compliant. If you connect an antenna onto it's N connector and calculate the EIRP to insure it's compliant, is NOT a modification.

A modified device can be operated under Part 97 if you're a ham. It can no longer be operated under Part 15 if you're a non-ham. There are pitfals and caveats no matter how you look at it. I don't know how much clearer that needs to be.

 

[drdiesel1]

Here is why is came up.

You have a part 15 device that has a 6dBi antenna that broke off the primary antenna jack. This particular device also has an internal U.fl connector. Using the same gain and type of antenna (omni, yagi, panel etc as original) can you utilize the internal connector and stay part 15 compliant?

What they mean is that some devices are plug and play, designed for consumer use. Others require "installation", as in climb a tower, hand a dish, bolt the radio into a rack, etc.

In that type of equipment, the EIRP requirements need to be determined and complied with.

I also believe the above is incorrect. On a device meant to be professional installed your only allowed to use antenna's at less than or equal to the antenna's used during the FCC certification.

For example, the FCC/Metlabs certified device A on a 6dBi omni and a 12 dBi panel. Hence your only allowed to use a max of a 6dBi omni or less on your install, same for the panel.

I'd love to see a written section on the statement above, this understanding has caused heated debate many times. Now consider I'm talking part 15 only. I'm full aware of the EIRP limits when operating in part 97.

 

[DaveNF2G]

Just for clarification, once a Part 15 device has been modified, it cannot be un-modified and then used as a Part 15 device again without re-certification.

 

[zz0468]

Here is why is came up.

You have a part 15 device that has a 6dBi antenna that broke off the primary antenna jack. This particular device also has an internal U.fl connector. Using the same gain and type of antenna (omni, yagi, panel etc as original) can you utilize the internal connector and stay part 15 compliant?

I don't think the rules are nitpicky enough to distinguish that between a repair and a modification. You're using the same type antenna, it's got the same gain, it's got the same ERP. I don't see a problem here.

I also believe the above is incorrect. On a device meant to be professional installed your only allowed to use antenna's at less than or equal to the antenna's used during the FCC certification.

Can you show me where in Part 15 it says that? Look closely at 15.407, and see how it deals with high gain antennas on point to point links. The language is quite technical, but it says that for some devices, there is no limitation on antenna gain. There is a limit on EIRP when using high gain antennas.

Simplified, it's stating that you can't use a large antenna to increase your ERP, but you can indeed use large antennas. There are scads of radios out there marketed to cellular carriers, telcos, business, ISP's, etc. that are intended to install in a rack, hook to the site's 48 volt battery plant, connect to a big antenna with a chunk of waveguide, and it's all legal.

The caveat is the operator of that device has to back down on the power. 15.407 shows you how.

I'd love to see a written section on the statement above, this understanding has caused heated debate many times. Now consider I'm talking part 15 only. I'm full aware of the EIRP limits when operating in part 97.

You can end the debate by looking up 47CFR part 15. It's all there. No hidden content or meaning. If you're curious as to what section of Part 15 a device might fall under, there should be a mention of the specific rule in the operator manual. The thing to remember, and maybe this is what's causing any debate is, there's different sections of Part 15 intended for different types of devices. A radio carrying a DS3 to a cell site is not subject to the same limitations as a wireless router in your living room.