K2: Change filter BW without realigning filters?

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K2: Change filter BW without realigning filters?

Andrew Moore-3
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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Re: K2: Change filter BW without realigning filters?

Don Wilhelm-4
  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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Re: [Bulk] K2: Change filter BW without realigning filters?

Bill Coleman-2
In reply to this post by Andrew Moore-3

On Dec 31, 2010, at 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

Yes.

It should be just a minor tweak to one sideband, and perhaps a larger adjustment to the other.

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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