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KX3 Baseband filter?

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Steve Ellington

KX3 Baseband filter?

Wayne made a comment during the video about the optional roofing filter being "baseband" instead of a crystal filter. Can someone explain what that means? Maybe I missed something.

Steve
N4LQ
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Bruce Beford-2

Re: KX3 Baseband filter?

"Baseband" refers to the fact that the QSD down-converts the RF to IQ
streams at directly near-audio range frequencies. The ADC converts this to
digital, and the DSP then does the demodulation. From the description, the
"IF" frequencies are in the 10 KHz range. So, the "baseband roofing" filter
will be a selectable active "audio" filter operating in this range, prior to
the ADC. This will prevent excessive "out of band" energy from reaching the
ADC.

Bruce, N1RX

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Rick Prather-2

Re: KX3 Baseband filter?

Thank you Bruce,

I was also puzzled by that part of the presentation.

Rick
K6LE

On 5/21/2011, at 8:01 , Bruce Beford wrote:

> "Baseband" refers to the fact that the QSD down-converts the RF to IQ
> streams at directly near-audio range frequencies. The ADC converts this to
> digital, and the DSP then does the demodulation. From the description, the
> "IF" frequencies are in the 10 KHz range. So, the "baseband roofing" filter
> will be a selectable active "audio" filter operating in this range, prior to
> the ADC. This will prevent excessive "out of band" energy from reaching the
> ADC.
>
> Bruce, N1RX
>

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P.B. Christensen

Re: KX3 Baseband filter?

According to Wayne, Rx performance will be similar to that of the Flex-3000.
With the KX3's QSD down-convert architecture, my guess is that all
performance parameters will be superb, with BDR specs probably well behind
the K3. I'm basing my opinion only on the little information available.
Who knows what other magic they developed to close the gap in performance.
It's hard to believe that such performance is attainable in a low-current
design. Take a look at Dan Tayloe's Norcal 2030. It's nearly a miracle
that he attained such high performance in a quadrature detector design and
yet the Rx current is less than 12 mA.

The KX3 effectively combines the best performance and portability attributes
of the Flex-3000 and Flex-1500 into a highly modular package. Once
available, I can't imagine anything better for a DXpedition. For
contesting, FD , etc., the K3 would still surpass it.

I really like the KX3 panel design. I'm still hoping that the next major
Elecraft transceiver continues with modular architecture to allow for a
choice in remote control panels between portable and base station sizes.
There's no longer a need to bind the hardware to the control surface.

Paul, W9AC

Original Message -----
From: "Rick Prather" <[hidden email]>
To: "Bruce Beford" <[hidden email]>
Cc: <[hidden email]>
Sent: Saturday, May 21, 2011 11:06 AM
Subject: Re: [Elecraft] KX3 Baseband filter?

> Thank you Bruce,
>
> I was also puzzled by that part of the presentation.
>
> Rick
> K6LE
>
> On 5/21/2011, at 8:01 , Bruce Beford wrote:
>
>> "Baseband" refers to the fact that the QSD down-converts the RF to IQ
>> streams at directly near-audio range frequencies. The ADC converts this
>> to
>> digital, and the DSP then does the demodulation. From the description,
>> the
>> "IF" frequencies are in the 10 KHz range. So, the "baseband roofing"
>> filter
>> will be a selectable active "audio" filter operating in this range, prior
>> to
>> the ADC. This will prevent excessive "out of band" energy from reaching
>> the
>> ADC.
>>
>> Bruce, N1RX
>>
>
> ______________________________________________________________
> 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

k6dgw

Re: KX3 Baseband filter?

"QSD" has always meant, "Your keying is defective." I'm guessing that
isn't what's meant here?

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org

On 5/21/2011 8:30 AM, Paul Christensen wrote:

> With the KX3's QSD down-convert architecture, my guess is that all
> performance parameters will be superb, with BDR specs probably well behind
> the K3.
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Bruce Beford-2

Re: KX3 Baseband filter?

In reply to this post by Steve Ellington

Quadrature Sampling Detector

> "QSD" has always meant, "Your keying is defective." I'm guessing that
> isn't what's meant here?

>73,

> Fred K6DGW

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Joe Subich, W4TV-4

Re: KX3 Baseband filter?

In reply to this post by P.B. Christensen

> Once available, I can't imagine anything better for a DXpedition.

I can ... the K3 with its *full* dual receive and reasonable size.
I am, admittedly, not a fan of "portable" or backpack radio but
the KX3 is simply too small and underpowered for my taste, The
benefits of a "real" 100W radio will still make a K3 the radio of
choice for DXPeditions over the KX3/PPX100 combination.

73,

... Joe, W4TV

On 5/21/2011 11:30 AM, Paul Christensen wrote:

> According to Wayne, Rx performance will be similar to that of the Flex-3000.
> With the KX3's QSD down-convert architecture, my guess is that all
> performance parameters will be superb, with BDR specs probably well behind
> the K3. I'm basing my opinion only on the little information available.
> Who knows what other magic they developed to close the gap in performance.
> It's hard to believe that such performance is attainable in a low-current
> design. Take a look at Dan Tayloe's Norcal 2030. It's nearly a miracle
> that he attained such high performance in a quadrature detector design and
> yet the Rx current is less than 12 mA.
>
> The KX3 effectively combines the best performance and portability attributes
> of the Flex-3000 and Flex-1500 into a highly modular package. Once
> available, I can't imagine anything better for a DXpedition. For
> contesting, FD , etc., the K3 would still surpass it.
>
> I really like the KX3 panel design. I'm still hoping that the next major
> Elecraft transceiver continues with modular architecture to allow for a
> choice in remote control panels between portable and base station sizes.
> There's no longer a need to bind the hardware to the control surface.
>
> Paul, W9AC
>
> Original Message -----
> From: "Rick Prather"<[hidden email]>
> To: "Bruce Beford"<[hidden email]>
> Cc:<[hidden email]>
> Sent: Saturday, May 21, 2011 11:06 AM
> Subject: Re: [Elecraft] KX3 Baseband filter?
>
>
>> Thank you Bruce,
>>
>> I was also puzzled by that part of the presentation.
>>
>> Rick
>> K6LE
>>
>> On 5/21/2011, at 8:01 , Bruce Beford wrote:
>>
>>> "Baseband" refers to the fact that the QSD down-converts the RF to IQ
>>> streams at directly near-audio range frequencies. The ADC converts this
>>> to
>>> digital, and the DSP then does the demodulation. From the description,
>>> the
>>> "IF" frequencies are in the 10 KHz range. So, the "baseband roofing"
>>> filter
>>> will be a selectable active "audio" filter operating in this range, prior
>>> to
>>> the ADC. This will prevent excessive "out of band" energy from reaching
>>> the
>>> ADC.
>>>
>>> Bruce, N1RX
>>>
>>
>> ______________________________________________________________
>> 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
>
> ______________________________________________________________
> 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
>