Tom Boucher wrote:
In message <[email protected]>, g3kev
<[email protected]> writes
>Square wave generators/dividers and class D/E amplifiers are fine for
>small antennas and low erp but NOT SUITABLE for larger antennas and high
>power. An abundance of LPF and BP filters might help to clean up the
>signal.
If you read the literature published by one of the researchers/experimenters
of class D/E amplifiers, he states that if you push the amplifiers, which
most amateurs do, and do not pay attention to the LPF, you are then radiating
a distorted square wave, with all its odd order harmonics, he goes on to say
that for larger than normal antenna systems one would need possible more than
the normal 5 pole filter between the mosfets and the antenna.
I own a quality spectrum analyser and can verify what he says to be correct.
Very few signals generated by such amplifiers and used by radio amateurs have
a pure sine wave output after one 5 pole LPF, except at very low power
levels, also have a look at the ripple content super imposed on the signal
because the power supplies normally used by radio amateurs are not regulated
or well smoothed. .
With your modest amplifier and long wire a few feet above ground you have
nothing to worry about.
G3KEV
Absolute rubbish!
73, Tom G3OLB
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