On K3 crystal filter gain compensation (FLx GN)

[wayne burdick]

Lately there has been some discussion about how much gain to add when
compensating for loss in the K3's individual crystal filters. The
general guideline is "as little as possible." I'd suggest starting with
0 and working up to as high as a few dB only if it seems necessary.

Narrow bandwidths themselves create a psychoacoustic "gain" effect, so
you don't really have to make up for the entire loss relative to wide
filters. Also, excessive gain can in extreme cases worsen the
performance of DSP signal processing, such as noise reduction (NR).
Finally, AGC tends to flatten signal amplitudes in general, further
reducing the need for per-filter compensation.

While I'm on this topic, I'd also like to suggest using a minimum of
both RX and TX EQ. The '0' levels were carefully determined
empirically, and in most cases the optimal values will be well below
the maximum range provided. Unless you have an aural sensitivity issue
in some pitch range, or a serious mic deficiency, I'd stay between +/-
6 dB. As with filter gain settings, excessive values can result in
adverse interaction with the DSP.

And yes, there will be per-mode RX EQ in a future firmware revision.
Thanks for all the suggestions on this.

73,
Wayne
N6KR

---

http://www.elecraft.com

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[Doug Turnbull]

Wayne,
   Oh so quickly the forecast comes true may I eat humble pie regarding the
earlier comments about features.   A separate RX EQ for CW and SSB might be
really useful.   I listen to CW with a low pitch close to 310 Hz and being
able to further attenuate high frequencies above 800 Hz might be agreeable
to my ears but of course I would not want to be constantly adjusting this
setting when I switch to listening on SSB.   You guys are good.

         73 Doug EI2CN


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[Leigh L. Klotz Jr WA5ZNU]

wayne N6KR wrote:
> And yes, there will be per-mode RX EQ in a future firmware revision.
> Thanks for all the suggestions on this.
>
>  
As long as you're still reading suggestiosn on per-mode RX EQ for the
future,
I think it'd be really fascinating to see RX EQ combined with AGC for
data modes.

As Lyle KK7P points out here:
  http://n2.nabble.com/K3-Overload-from-WYFR-td3077727.html#a3077784

  " "The K3 blocking dynamic range is 20 to 30 dB better than PC-based
SDRs."

Digimode programs suffer the same fate as PC-based SDR, and have reduced
dynamic range.
Of course, you can use the K3's DSP and IF filters manually to block out
QRM,
but it would be really neat if there were a way to ask the K3 apply AGC
in bins
across the receive passband, instead of wholesale across the receive
passband.

Leigh/WA5ZNU
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