[Elecraft] New K3 SN#207 built but question on AM Filter

[David Woolley (Elecraft)]

John W2XS wrote:

> the other).  If the highest modulating frequency is 5kHz, then the BW of
> each sideband will be 5kHz, and the total AM signal will have a BW of 10kHz.
> At the receiver, one of the sidebands is discarded, and the other is
> demodulated. So, a 6kHz filter should produce a nice sounding AM signal
> since a 5kHz-wide signal is passing through it.

If  you do that with standard AM (envelope) detection, you will get up 
to about 20% (even) harmonic distortion.  You will probably get better 
audio treating it as SSB, in spite of frequency and phase errors.

To reproduce single sideband full and reduced carrier signals 
accurately, you need synchronous detection.  (It should also be quieter 
for double sideband full carrier.)

(For Scroggie fans, consider the phasor diagram for 100% modulation at 
the point where the sideband is at 90 degrees to the carrier.  That 
gives an amplitude of sqrt(2) when you should just have the nominal 
carrier amplitude of 1.  At 0 and 180 degrees, you get the expected 
amplitudes of 2 and 0.)


-- 
David Woolley
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