[Elecraft] FM Filter for AM?

[Joe Subich, W4TV]

 > The present filter imitations serve to protect some of us
 > from both unintended and intentional excessive bandwidth.

AM/ESSB/SSB bandwidth is determined by the DSP modulation
not the roofing filter bandwidth.  This can easily be seen
in the use of the 6 KHz filter for ESSB where the occupied
bandwidth (3.0 - 4.0 KHz) options are significantly less
than the -6 dB bandwidth of the AM filter.

In any case, even the tightest filter will not prevent
"wide" signals caused by over driving the final amplifier
since the filtering occurs well before the amplifier.

Quite simply, the only time the SSB filter controls the
bandwidth is with analog SSB generation using the filter
method.  With both AM and SSB generated by either the
phasing method or using DSP techniques, the bandwidth is
determined by the bandwidth of the audio input (that is,
the highest modulating frequency.

73,

    ... Joe, W4TV

On 10/8/2010 1:58 PM, Ken Kopp wrote:
>
> If this change is made, we should be prepared for
> complaints about Elecraft transmitters being "wide",
> "splattering", etc.  The present filter imitations serve
> to protect some of us from both unintended and intentional
> excessive bandwidth.
>
> Elecraft's excellent reputation for "clean" transmitters will
> likely be tarnished.
>
> 73! Ken Kopp - K0PP
>         ElecraftCovers at rfwave.net
>
>
>
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