[Elecraft] Shortwave filters for K3

[Steve Ellington]

Don
Please believe me. I'm not confused. It just needs to be made clear to 
people who purchase the 13 Khz filter will only see 5 Khz on the display. 
Someone else asked the original question because HE was confused and I can 
understand why. I don't recall this to ever be a point of confusion on any 
other rig.
Steve Ellington
N4LQ at carolina.rr.com
----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: "Steve Ellington" <n4lq at carolina.rr.com>
Cc: <elecraft at mailman.qth.net>
Sent: Sunday, May 03, 2009 5:03 PM
Subject: Re: [Elecraft] Shortwave filters for K3


> Steve,
>
> Please do not be confused.  The DSP *is* at the IF frequency, *and it 
> does* process AM at the full bandwidth for all modes as required.
>
> The AM bandwidth *used to be* displayed as the IF bandwidth, but many were 
> confused because it was double the bandwidth that could be heard - so it 
> was changed to *display* the audio bandwidth.
> It is a matter of display only, and not the actual operating IF width.
>
> The display of the audio bandwidth in AM is consistent with the bandwidth 
> displayed for other modes - the audio bandwidth is what is displayed.  (FM 
> might be different, I don't have the FM filter to try).  In any case, now 
> the DSP displayed bandwidth is equal to the audio bandwidth, no matter 
> what the actual IF processing width may be.
>
> 73,
> Don W3FPR
>
> Steve Ellington wrote:
>> Don
>> I understand the demodulation theory just fine but the concept of having 
>> the DSP act as an audio filter instead of an IF filter causes some 
>> confusion since we've been hyping up "IF-DSP" filtering for several years 
>> now and suddenly we talk about AF-DSP in only one mode, AM.
>> Maybe if the BW display showed 10 Khz instead of 5 Khz it would limit the 
>> confusion since that seems to be what most of us are used to. We 
>> understand that we only hear one of the two sidebands anyway. Oh well,,, 
>> I guess the question will keep coming up.
>> Steve Ellington
>> N4LQ at carolina.rr.com
>>