[Elecraft] Taming the SSB receive dragon

Don Wilhelm w3fpr at embarqmail.com
Sat Feb 11 16:48:05 EST 2012


Bill,

I have 2 suggestions - first for SSB, use Hi/Lo Cut instead of shift and 
width - set the Lo Cut at 200 or 250 (300 or 350 if there is QRM on the 
low frequency end), and then use the Hi Cut to control the width of the 
received passband - the K3 algorithms automatically take care of the 
center frequency.  Yes, it can be a real challenge to adjust both the 
shift and width to obtain a good sounding signal - you must adjust shift 
if you change width in order to maintain intelligible copy.
That is not a K3 limitation, but a limitation of our ears hearing human 
speech.  There must be content in the 300 to 400 Hz range to maintain 
intelligibility - so you cannot cut the low end very much - OTOH, the 
high end may be cut drastically and still maintain intelligibility even 
though doing so removes some of the smoothness and naturalness from the 
voice.

Secondly (on your background hiss problem), I suggest you read the 
"Noisy K3" article on my website www.w3fpr.com and adjust your AGC slope 
and threshold parameters in light of that article.  I believe you went 
the wrong way with your AGC slope - the AGC settings are a personal 
preference, but do it with knowledge of what should happen with the 
various settings - my article tries to give you that information.

73,
Don W3FPR

On 2/11/2012 3:58 PM, Bill wrote:
> I have only had the K3 for a few days and have already experienced a
> couple of headaches from listening to hours and hours of SSB in rag
> chews and nets on 75 meters.  When compared to my trusty Kenwood TS-480,
> the K3's receiver was far too harsh.
>
> I process the receive audio through a Behringer mixer panel and into a
> pair of Behringer Ms40 speakers - hence, both radios get the exact same
> chance at sounding really good.
>
> I did some research into the problem and read what other ops had done to
> correct the problem. Then I applied those gleanings to my K3:
>
> I run the 2.7 filter open (full WIDTH)
> I set the SHIFT to 1.3 (mellows things out a little)
> The AGC SLP is set to 15 (this slayed the wow-wow dragon)
> The AFX Delay at 2 (can change with the mood)
> RX EQ: +3  +3  +2   0  +1  +1  +1  -1 (you can play with this forever)
>
> Now I have that wonderful Kenwood receive audio back. Couple that with
> the arsenal of the K3's QRM/QRN tools afforded by the DSP and a 2.1
> filter - and I can hear through almost anything. I am impressed with the
> K3 - it is a keeper - affording fine listening quality.
>
> There are two more receive dislikes I will be working at getting rid of:
>
> 1. General background hiss - which is more noticeable on the K3 than the
> 480 (even using the ATT and reducing the RF Gain). I live in a quiet
> rural location - it should be quieter than it is.
> 2. The NOTCH (auto) - introduces an unpleasant variation to the signal -
> specifically, a slight warble.
>
> I am open to suggestions and comments.
>
> Bill W2BLC
>


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