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List:       elecraft
Subject:    Re: [Elecraft] K2: Change filter BW without realigning filters?
From:       Don Wilhelm <w3fpr () embarqmail ! com>
Date:       2010-12-31 17:53:16
Message-ID: 4D1E188C.5060209 () embarqmail ! com
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  Andrew,

The easy answer is YES.

The Lower sideband setting will not change much, but the upper sideband 
BFO will change a lot.

Do you have the KSB2 fitted to your K2?  If so, I recommend you use it 
for a wide CW filter rather than using the variable filter at such a 
wide width - at wide widths (over 1.5 kHz) the filter passband becomes 
quite ragged within the passband, and would be quite noticeable with CW 
although it will provide intelligible SSB copy.  If you choose the OP1 
filter for a wide CW filter, just set the BFOs to the same frequency (or 
DAC value) as you have for a properly aligned SSB filter.

In other words, 1.50 kHz was chosen as the wide CW default because that 
is about the widest that the variable filter can be set and expect a 
relatively flat passband.

Use Spectrogram and a wideband noise generator for best results when 
setting the filter BFOs.  If you are not familiar with the process, take 
a look at part 3 of the K2 Dial Calibration article on my website 
www.w3fpr.com

73,
Don W3FPR

On 12/31/2010 11:24 AM, Andrew Moore wrote:
> For best performance do I need to realign BFO settings (Spectrogram etc.) if
> I change the filter bandwidth setting on the K2?
>
> ex: FIL1 from the usual 1.50 to 2.49
> etc...
>
> --Andrew, NV1B
>
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