On 6/29/2016 12:19 PM, Jeff Liebermann wrote:
On Wed, 29 Jun 2016 11:29:12 -0400, rickman wrote:

Mostly yet.

That should be "yes". In a hurry today (like all other days).

However, some bands do not require a license and operate
under FCC Part 15:
http://www.lwca.org
https://en.wikipedia.org/wiki/LowFER
http://www.arrl.org/lf-low-frequency
https://hackaday.io/project/6882-lowfer-transmitter-for-your-arduino
etc...

Very interesting. I see a difference between the ARRL article and the
Hackaday page. ARRL says the power limit on the US 1750 meter "free
band" is 1 W into the "transmitter's final stage" while the Hackaday
page says the limit is 1 W into the "feedline" and antenna system.

This might help:
http://www.lwca.org/sitepage/part15/index-what.htm
http://lwca.org/library/reference/
Note that it's a bit out of date. Adjust the links for 2016.
You want part 15.217 (Operation in the band 160-190 kHz.)
http://www.ka7oei.com/ct_lowfer_archive.html

I see that kind of stuff quite a bit in the FCC rules-n-regs. They
sometimes fail to specify WHERE the transmit power is to be measured.
Is it at the input to the xmitter, output of the xmitter or at the end
of a lossy feed line. What does one do if the system is not 50 ohms?
I don't have an answer and since the FCC never will admit to making a
mistake, it's unlikely to be fixed. Should you ask for clarification,
you'll probably get an answer from the FCC which you don't want to
hear. Been there, many times. My best advice is do your best with
what you have, don't try to play FCC attorney, and muddle onward into
the unknown.

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.

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.

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.

--

Rick C