[Elecraft] K2 Filter Shape Factors

Sat Apr 10 22:51:01 2004

Darrell,

I don't know of any advantage or disadvantage to using any particular
sidetone pitch.  The only point that I can make about it is that the way you
align the CW filters/BFOs should be modified when the bandpass width
approaches twice the sidetone pitch.

If your passband width is 2X the sidetone pitch, AND the filter passband is
centered at the sidetone pitch, you will have an in-passband response down
to zero frequency and possibly across to the other side of zero - therefore
you sacrifice single-signal reception.  I would recommend that the BFO be
set to skew the filter center upward a bit so that the low (audio) frequency
side of the filter is somewhere between 100 and 300 Hz - you take your pick
of the exact frequency - but be consistent for all the relatively wider
filters (center the more narrow ones as usual).

73,
Don W3FPR

----- Original Message ----- 
From: "Darrell Bellerive" <[email protected]>
To: "Elecraft Email List" <[email protected]>
Sent: Saturday, April 10, 2004 9:13 PM
Subject: Re: [Elecraft] K2 Filter Shape Factors

> As Eric points out below, the CW filter is optimized for 400 Hz
> bandwidth. Is there a similar optimization for offset/sidetone
> frequency? Other than personal tonal preferences, what are the
> advantages and disadvantages of the offset/sidetone set to 400 Hz vs.
> 600 Hz vs. 800 Hz etc?
>
> Darrell   VE7CLA   K2 #1973
>
> On Sat, 2004-04-10 at 16:41, Eric Swartz WA6HHQ - Elecraft wrote:
> > Above 1000 Hz you will see increasing ripple in the variable CW filter.
At 1.2
> > kHz and above it has significant ripple and a wider shape factor and is
really
> > only intended for tuning the band and casual SSB reception.
> >
> > It is optimized for impedance match at around 400 Hz or so. It can be
set
> > wider for SSB receive, but is not optimal. For best SSB reception the
fixed
> > filter on the SSB board has a much better, flatter response :-)
> >
> > 73, Eric   WA6HHQ
> > ------
> >
>
>
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