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

[John W2XS]

I am hoping that Elecraft will have a different option for AM listening by
the time that my K3 arrives (in April).  A simple, lower-cost ceramic filter
would be nice.  Or, perhaps the roofing filter can be bypassed for AM
listening. There are several receivers out there that have DSP-only
selectivity for AM or SW listening. Or, at least, the audio BW will be
opened up to 6kHz for AM listening.

I ordered the 6kHz filter thinking that I can use the entire 6kHz for AM
listening.  The process of amplitude modulation produces 2 sidebands and a
carrier.  Each sideband has the same information (one is a mirror-image of
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.

(I have heard some SW stations that must be using a wider bandwidth, based
on how nice they sound on an old Hallicrafters radio.  Radio China
International comes to mind).

Not to be able to have a 6kHz BW with a 6KHz filter is a surprising
limitation (IMHO).

72,

John W2XS
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