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KX3 roofing filters

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Joseph Trombino, Jr

KX3 roofing filters

Fellow Elecrafters:

Does anyone have info on the KX3 roofing filters, i.e. how many can the KX3 contain??? Bandwidths???

Looks like the ultimate portable rig to me....sure hope they can keep up with the expected demand (grin).

73, Joe W2KJ
I QRP, therefore I am
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Alan Bloom

Re: KX3 roofing filters

>From the new KX3 web page, the optional roofing filters:

KXFL3 Roofing Filter Module (500/1500/2700/3800 Hz)

The one option gives you all four roofing filters.

Al N1AL

On Thu, 2011-05-26 at 15:01 -0400, Joseph Trombino, Jr wrote:

> Fellow Elecrafters:
>
> Does anyone have info on the KX3 roofing filters, i.e. how many can the KX3 contain??? Bandwidths???
>
> Looks like the ultimate portable rig to me....sure hope they can keep up with the expected demand (grin).
>
> 73, Joe W2KJ
> I QRP, therefore I am
> ______________________________________________________________
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Guy, K2AV

Re: KX3 roofing filters

Ah. Extremely important point. NOT at all apparent from the KX3
page, especially when used to the one filter, one bandwidth paradigm.
As it stands it reads like four available, but only one installable.

On the web page, you may want to change...

"Narrow roofing filter option with four bandwidths (500 Hz, 1500 Hz,
2700 Hz, 3800 Hz) for excellent dynamic range"

... to something like...

"Narrow roofing filter, single option containing four bandwidths (500
Hz, 1500 Hz, 2700 Hz, 3800 Hz) for excellent dynamic range"

73, Guy.

On Thu, May 26, 2011 at 3:25 PM, Alan Bloom <[hidden email]> wrote:

> >From the new KX3 web page, the optional roofing filters:
>
> KXFL3 Roofing Filter Module (500/1500/2700/3800 Hz)
>
> The one option gives you all four roofing filters.
>
> Al N1AL
>
>
> On Thu, 2011-05-26 at 15:01 -0400, Joseph Trombino, Jr wrote:
>> Fellow Elecrafters:
>>
>> Does anyone have info on the KX3 roofing filters, i.e. how many can the KX3 contain??? Bandwidths???
>>
>> Looks like the ultimate portable rig to me....sure hope they can keep up with the expected demand (grin).
>>
>> 73, Joe W2KJ
>> I QRP, therefore I am
>> ______________________________________________________________
>> 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
>>
>
>
> ______________________________________________________________
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Jim Dunstan-2

Re: KX3 roofing filters

At 04:37 PM 5/26/2011 -0400, you wrote:

>Ah. Extremely important point. NOT at all apparent from the KX3
>page, especially when used to the one filter, one bandwidth paradigm.
>As it stands it reads like four available, but only one installable.
>
>On the web page, you may want to change...
>
>"Narrow roofing filter option with four bandwidths (500 Hz, 1500 Hz,
>2700 Hz, 3800 Hz) for excellent dynamic range"
>
>... to something like...
>
>"Narrow roofing filter, single option containing four bandwidths (500
>Hz, 1500 Hz, 2700 Hz, 3800 Hz) for excellent dynamic range"
>
>73, Guy

Hi,

My interpretation is that the "narrow roofing filter option" is variable
with 500, 1500, 2700, and 3800 hz steps that follow the DSP filter as it's
bandwidth is changed.

Jim, VE3CI

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Larry Walker

kx3 roofing filter

In reply to this post by Joseph Trombino, Jr

Is this "one size does all" roofing filter the one alluded to at the
beginning of the K3 campaign that would be available at some point down
the line?

Will it fit the K3 or just KX3?

Larry
kw4a
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Bill W4ZV

Re: KX3 roofing filters

In reply to this post by Jim Dunstan-2

Jim Dunstan-2 wrote

My interpretation is that the "narrow roofing filter option" is variable
with 500, 1500, 2700, and 3800 hz steps that follow the DSP filter as it's
bandwidth is changed.

These filters are ahead of the DSP at baseband. They protect the ADC from overload and should result in better Blocking Dynamic Range (BDR), which has been a weakness of most SDRs.

73, Bill

Don Wilhelm-4

Re: kx3 roofing filter

In reply to this post by Larry Walker

Larry,

It is not for the K3, it will only work in the KX3.
From what I can imagine (and it is only MY imagination), it is more
akin to an active bandpass filter (like an audio filter, but at the high
end of the audio range) where it filters the 11 kHz IF before the signal
hits the ADC converter. That should be almost as effective at reducing
strong off-frequency signals that are within the receiver passband.
Wayne did say they were "baseband" filters, so I am extending that
statement without further detailed knowledge - excuse me if I got it wrong.

The K3 uses crystal filters at the 8 MHz 1st IF, the KX3 roofing filters
work at the 2nd IF, but should still be quite effective.

73,
Don W3FPR

On 5/26/2011 6:16 PM, Larry Walker wrote:
> Is this "one size does all" roofing filter the one alluded to at the
> beginning of the K3 campaign that would be available at some point down
> the line?
>
> Will it fit the K3 or just KX3?
>
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Jim Dunstan-2

Re: KX3 roofing filters

In reply to this post by Bill W4ZV

At 03:30 PM 5/26/2011 -0700, you wrote:

>Jim Dunstan-2 wrote:
> >
> > My interpretation is that the "narrow roofing filter option" is variable
> > with 500, 1500, 2700, and 3800 hz steps that follow the DSP filter as it's
> > bandwidth is changed.
> >
>
>These filters are ahead of the DSP at baseband. They protect the ADC from
>overload and should result in better Blocking Dynamic Range (BDR), which has
>been a weakness of most SDRs.
>
>73, Bill

Hi,

Yes, that is what I understand. I didn't mean that the filter comes after
the DSP ... it comes before the DSP filter ... but it's bandwidth is
adjusted according to the DSP bandwidth .... as the DSP bandwidth is
changed the roofing filter will follow. The filter is at a vy low frequency
prior to the ADC ... I am wondering what kind of filter it is as it
certainly can't be a xtal filter at this vy low frequency .... has to be
some kind of software controlled filter.

Jim, VE3CI

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Ross Primrose N4RP

Re: kx3 roofing filter

In reply to this post by Don Wilhelm-4

On 5/26/11 6:38 PM, Don Wilhelm wrote:
> The K3 uses crystal filters at the 8 MHz 1st IF, the KX3 roofing filters
> work at the 2nd IF, but should still be quite effective.

Actually, at least as I understand it, the KX3 is direct conversion, to
the KX3 roofing filter option is at the first "IF" as well...

73, Ross N4RP

--
FCC Section 97.313(a) “At all times, an amateur station must use the minimum transmitter power necessary to carry out the desired communications.”

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Mike Morrow-3

KX3 roofing filters

In reply to this post by Joseph Trombino, Jr

> I am wondering what kind of filter it is as it certainly can't be a xtal
> filter at this vy low frequency .... has to be some kind of software
> controlled filter.

I think that I heard Wayne say at the Elecraft display in Dayton that they
were mechanical filters.

Mike / KK5F
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Bruce Beford-2

Re: KX3 roofing filters

In reply to this post by Joseph Trombino, Jr

Not a mechanical filter, but a low noise active "audio" filter running
around 11 KHz prior to the ADC. The 4 selectable bandwidths will help keep
unwanted off-signal energy out of the ADC.
-Bruce, N1RX

> I think that I heard Wayne say at the Elecraft display in Dayton that they
> were mechanical filters.

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