On Wed, 29 Jun 2016 12:53:28 -0400, rickman wrote:

I'm back from the dentist drilling holes in my teeth and bank account.

Thanks for the links. I found 15.217 and it says,

15.217 Operation in the band 160–190 kHz.
(a) The total input power to the final
radio frequency stage (exclusive of fila-
ment or heater power) shall not exceed
one watt.

Yep, that's it.

Since they specifically exclude the filament power I supposed that 1
watt limit is on the power from the supply rather than the "input" power
to the grid/base/gate of the active element. So in reality the 1 watt
limit at the input to the final stage will produce less than 1 watt at
the output of the final stage.

With the frequency being so low, a class D output could potentially
provide nearly the full watt to the feedline I expect. Some amount of
filtering would be needed to prevent the carrier from making it out the
antenna, but using sigma-delta techniques should help to minimize that.

Yep, except why bother with an amplifier? You could just modulate a
200Khz switching power supply and get similar results. Lots of other
options available, but few of them involve a traditional amplifier
multiplier chain.

With such low power and simple output stage, it could be placed at the
antenna which would allow the full 15 meters to be antenna.

Any way you look at it, it's going to be flea power buried under tons
of atmospheric noise. Everything you do up to about 300 meters range
is near field.
http://www.part15.us/forum/part15-forums/general-discussion/part-15-am-communications-near-field
http://www.part15.us/forum/part15-forums/general-discussion/longwave-broadcast-dx-171-khz

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558