KX3

[john daws]

(not sure if this is the same as using the KX3 users group but here goes)

Would appreciate advice on the use of the* notch filter* on my KX3

It is fitted with* KX3FL3* roofing filters. I only use CW

Once I have spotted a weak signal I can  use these to narrow down and
filter out unwanted noise on the chosen signal

I can also apply the APF filter and tune that way.

Recent advice suggested that the APF function  works best when when used
with a  DSP/crystal filter WIDTH setting of 300-500 Hz

Does this mean I switch on the Notch and tune to this range on the notch
setting and how does this work with the bandwidth settings on the PBT
function?

Do I leave the notch on whilst tuning for other signals or only use it when
I have a weak signal in the first place.

Trial and error has left me doubtful whether I am getting the best out of
this function.

Any advice most welcome.

Thanks

john M6KET
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[Don Wilhelm]

John,

This reflector covers all Elecraft products.

The notch filter is only used to notch out an *unwanted* signal - use it
carefully since you can easily notch out the signal that you are trying
to receive.

First use the DSP filter to home in on the wanted signal - the PBT knob.
  The roofing filter will follow along with the width of the DSP passband.

Once you get the wanted signal, you can optionally use APF if it is of
benefit.

If there is an unwanted signal within the passband, you can use NOTCH to
reduce it.

73,
Don W3FPR

On 4/24/2018 6:03 AM, john daws wrote:

> (not sure if this is the same as using the KX3 users group but here goes)
>
> Would appreciate advice on the use of the* notch filter* on my KX3
>
> It is fitted with* KX3FL3* roofing filters. I only use CW
>
> Once I have spotted a weak signal I can  use these to narrow down and
> filter out unwanted noise on the chosen signal
>
> I can also apply the APF filter and tune that way.
>
> Recent advice suggested that the APF function  works best when when used
> with a  DSP/crystal filter WIDTH setting of 300-500 Hz
>
> Does this mean I switch on the Notch and tune to this range on the notch
> setting and how does this work with the bandwidth settings on the PBT
> function?
>
> Do I leave the notch on whilst tuning for other signals or only use it when
> I have a weak signal in the first place.
>
> Trial and error has left me doubtful whether I am getting the best out of
> this function.

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[Petr, OK1RP/M0SIS]

John,

just to know, there are no xtal filters in KX3. Just single audio filter at
11kHz in front of DSP.

Also check the NR article by Lyle, KK7P here:
http://www.elecraft.com/K3/Lyle%20Johnson%20explains%20Noise%20Reduction.htm

as same as APF by Wayne, N6KR:
http://elecraft.365791.n2.nabble.com/APF-audio-peaking-filter-on-the-K3-K3S-KX3-td7613416.html

73 - Petr, OK1RP



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[wayne burdick]

Hi Petr,

The KXFL3 option operates at baseband (0 to 3 kHz), not 11 kHz. It is actually two filters, one for “I” and the other for “Q” (the quadrature signal paths). Each filter has two LPFs, one for CW, the other for SSB and data. To keep the phase and amplitude balanced, we use capacitors that are hand-trimmed to 0.25% tolerance. The result is an effective roofing filter for the ADCs and DSP.

If the KXFL3 is not installed, the radio uses an 8 kHz IF, like the KX2.

73,
Wayne
N6KR

> On Apr 24, 2018, at 11:23 PM, Petr, OK1RP/M0SIS <[hidden email]> wrote:
>
> John,
>
> just to know, there are no xtal filters in KX3. Just single audio filter at
> 11kHz in front of DSP.
>
> Also check the NR article by Lyle, KK7P here:
> http://www.elecraft.com/K3/Lyle%20Johnson%20explains%20Noise%20Reduction.htm
>
> as same as APF by Wayne, N6KR:
> http://elecraft.365791.n2.nabble.com/APF-audio-peaking-filter-on-the-K3-K3S-KX3-td7613416.html
>
> 73 - Petr, OK1RP
>
>
>
> -----
> http://ok1rp.blogspot.com
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
> Elecraft mailing list
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> Please help support this email list: http://www.qsl.net/donate.html
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[Petr, OK1RP/M0SIS]

Wayne,

thank you for specifying more details about the KXFL3.
I am sure it is helpful to all KX3 users.

If I remember well somewhere it was mentioned that the extremely tight
tolerances on the capacitors are even 0.1% in some cases and matched by
hand...

Best regards,
73 - Petr, OK1RP



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[wayne burdick]

I’d have to review our production specifications to get the actual figures. But the point is that by matching these capacitors to an extremely close tolerance, their contribution to phase imbalance is negligible.

73,
Wayne
N6KR

> On Apr 25, 2018, at 9:39 AM, Petr, OK1RP/M0SIS <[hidden email]> wrote:
>
> Wayne,
>
> thank you for specifying more details about the KXFL3.
> I am sure it is helpful to all KX3 users.
>
> If I remember well somewhere it was mentioned that the extremely tight
> tolerances on the capacitors are even 0.1% in some cases and matched by
> hand...
>
> Best regards,
> 73 - Petr, OK1RP
>
>
>
> -----
> http://ok1rp.blogspot.com
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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