433MHz Maximum Tx level in Texas if that matters) ?

[Jester]

I did some preliminary testing of HC-12 modules operating at 433MHz, they seems to work pretty well. Near 1000' at 1/10 output power level.

I'm not up on the FCC rules, any of you Southern guys and gals no if these HC12 modules can be used license free in the USA and if so, at what maximum power levels?  Idea was to use in Texas if that matters.  Data will be sent very intermittently perhaps a few seconds per day total in a few bursts of 15-50 ms.

Thanks

[nealix]

These boards can transmit in two licensed bands, requiring the appropriate radio license in order to be legal
and to coordinate/avoid interference.  430-450 MHz requires an amateur radio license, and channels above
450 MHz would require a different license.

Permitted power level is based on which band you are using, and what class your license is.

For those who enjoy ignoring the rules, licensed users in both of the above bands have
excellent equipment and skills for locating rogue signals and pin-pointing the exact
location.

Get licensed or DO NOT USE.
Just because an international seller can offer something on eBay, that does not
automatically mean it is legal to use it in your specific country/location.
In fact, various vendors paid $millions$ in fines last year due to this same
type of thing;  Selling modules and equipment to USA buyers that violated
local licensing and use requirements.
Ignoring the rules can be very expensive.

[bdunham7]

These boards can transmit in two licensed bands, requiring the appropriate radio license in order to be legal
and to coordinate/avoid interference.  430-450 MHz requires an amateur radio license, and channels above
450 MHz would require a different license.

Permitted power level is based on which band you are using, and what class your license is.

For those who enjoy ignoring the rules, licensed users in both of the above bands have
excellent equipment and skills for locating rogue signals and pin-pointing the exact
location.

Get licensed or DO NOT USE.
Just because an international seller can offer something on eBay, that does not
automatically mean it is legal to use it in your specific country/location.
In fact, various vendors paid $millions$ in fines last year due to this same
type of thing;  Selling modules and equipment to USA buyers that violated
local licensing and use requirements.
Ignoring the rules can be very expensive.

The law actually appears to allow this sort of use without licensing, within certain limitations and subject to interpretation.  There are all sorts of these devices and the only reason I can think of why they'd be illegal is exceeding power limits, which is what the OP appears to want to know about.  I don't know anything about the HC-12 specifically, but the rules are here:

https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-15/subpart-C/subject-group-ECFR2f2e5828339709e/section-15.231

It looks to me that the OP's device would at least be permissible under section (e) provided it meets the power limits.