In article , says...

Here's a question I can't seem to find the answer to: what are the
harmonic emission requirements for spectral purity for HF radio
transceivers in the US? I *think* its either -30 or -40db below, but
it's been years since I've used these transceivers. Thanks.




Look in the FCC part 97 rules. Such as he

http://www.arrl.org/files/file/Regul...08,%202018.pdf




(d) For transmitters installed after January 1, 2003, the mean power of
any spurious emission from a
station transmitter or external RF power amplifier transmitting on a
frequency below 30 MHz must be at
least 43 dB below the mean power of the fundamental emission. For
transmitters installed on or before
January 1, 2003, the mean power of any spurious emission from a station
transmitter or external RF
power amplifier transmitting on a frequency below 30 MHz must not exceed
50 mW and must be at least
40 dB below the mean power of the fundamental emission. For a
transmitter of mean power less than 5
W installed on or before January 1, 2003, the attenuation must be at
least 30 dB. A transmitter built
before April 15, 1977, or first marketed before January 1, 1978, is
exempt from this requirement.
(e) The mean power of any spurious emission from a station transmitter
or external RF power
amplifier transmitting on a frequency between 30-225 MHz must be at
least 60 dB below the mean power
of the fundamental. For a transmitter having a mean power of 25 W or
less, the mean power of any
spurious emission supplied to the antenna transmission line must not
exceed 25 µW and must be at least
40 dB below the mean power of the fundamental emission, but need not be
reduced below the power of
10 µW. A transmitt