Not too much is happening on the forum tonight so I'll take the mic.
This week I've been alternating between the essays of John-Paul Sartre and the Rules Part 15 of the FCC, so I think I'll start writing essays on rules.
15.21 is informative, and answers a mistaken belief held by some that "making changes to a certified transmitter voids the certification." That's not true. Not according to "15.21 Information to user - The users manual for an intentional or unintentional radiator shall caution the user that changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment."
First, we see that it will not void the certification, but only the user's authority to operate the equipment. That's a different thing.
Second, it COULD void the user's authority to operate the equipment. It doesn't say it WILL void the user's authority.
Don't be in such a hurry. 15.23 is perhaps even more interesting.
15.23 Home-built devices. (a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use.
This answers a question we had earlier today, about whether a home-made carrier current transmitter would be eligible for use. Obviously the answer is yes.
But there's more to 15.23:
"(b) It is recognized that the individual builder of home-built equipment may not possess the means to perform the measurements for determining compliance with the regulations. In this case, the builder is expected to employ good engineering practices to meet the specified technical standards to the greatest extent practicable."
Since (b) is bundled under "Home-built devices" we are obliged to believe that it only relates to "home-built equipment" and not any other kinds of Part 15 equipment, but it reveals a small glimmer of humanity in recognizing radio hobbyists as deserving respect for their interest.
Unless the FCC meant (b) to apply to all Part 15 at home hobbying and just messed up on collation. It could happen.
I've been pointing to 15.23 for years.. Every time someone tells me "it's not exactly calibrated, therefore illegal."
Part 15.23, a little wiggle room there.
That's good.
Bruce, DOGRADIO