Kx3 receiver

[J. Fielden]

is the kx3 receiver RF direct sampling or ?

--
72/73, Jim - wa4ar
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[Don Wilhelm-4]

Not direct sampling if by that you mean an ADC at the antenna.

The KX3 downconverts the signals to baseband (audio range) with a pair
of mixers that are operated 90 degrees out of phase, then converts the
resulting mixer outputs to digital, then processes the digital signals
for demodulation, filtering, etc.

The KX3 can also convert to 8kHz rather than baseband if needed, but the
use of the roofing filter is not possible when that is used.

73,
Don W3FPR

On 1/28/2016 8:15 PM, J. Fielden wrote:
> is the kx3 receiver RF direct sampling or ?
>

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[wayne burdick]

J. Fielden <[hidden email]> wrote:

> is the kx3 receiver RF direct sampling or ?

Hi Jim,

The KX3's architecture is pretty unique. First, we use a quadrature downconverter to get I and Q signals at a baseband (zero Hz) I.F. Using a zero I.F. allows us to insert optional high-performance analog roofing filters into the path, protecting the A-to-D converter and DSP from out-of-band signals. The roofing filter module includes a narrow filter for CW and a medium filter for SSB/DATA.

When the filters are installed, the KX3 has blocking dynamic range of nearly 140 dB, higher than that of even the most advanced direct-sampling radios. (But not quite as high as the K3S, which uses a superhet architecture with crystal filters to obtain off-the-charts dynamic range in the 150 dB range.)

With the filter module, the KX3 places 5th on Sherwood's receiver performance chart:

   http://www.sherweng.com/table.html

Even without this module, the KX3 receiver would still be in the top ten.

That's the long answer :)

73,
Wayne
N6KR


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[Igor Sokolov-2]

Most of the time I cannot use zero IF because of the direct AM detection. I
could not do that even far away from strong AM transmitters while operating
from Maldives. I end up setting 8 kHz IF in the radio and using it all the
time. This means that analog roofing is useless for me and blocking dynamic
range is degraded to the extend that operation of 2 radio on the same band
with separated antennas or sometimes even different bands(SO2R or MS
environment) is not possible with KX3 even though it is possible with a pair
of K3. KX3 is travelers radio for single op and it mates well with Expert
1.3K-FA. The latter requires only 5-7 Watt to give you 1 KW out.

73, Igor UA9CDC

----- Original Message -----
From: "Wayne Burdick" <[hidden email]>
To: "J. Fielden" <[hidden email]>
Cc: <[hidden email]>
Sent: Friday, January 29, 2016 6:55 AM
Subject: Re: [Elecraft] Kx3 receiver

> J. Fielden <[hidden email]> wrote:
>
>> is the kx3 receiver RF direct sampling or ?
>
> Hi Jim,
>
> The KX3's architecture is pretty unique. First, we use a quadrature
> downconverter to get I and Q signals at a baseband (zero Hz) I.F. Using a
> zero I.F. allows us to insert optional high-performance analog roofing
> filters into the path, protecting the A-to-D converter and DSP from
> out-of-band signals. The roofing filter module includes a narrow filter
> for CW and a medium filter for SSB/DATA.
>
> When the filters are installed, the KX3 has blocking dynamic range of
> nearly 140 dB, higher than that of even the most advanced direct-sampling
> radios. (But not quite as high as the K3S, which uses a superhet
> architecture with crystal filters to obtain off-the-charts dynamic range
> in the 150 dB range.)
>
> With the filter module, the KX3 places 5th on Sherwood's receiver
> performance chart:
>
>   http://www.sherweng.com/table.html
>
> Even without this module, the KX3 receiver would still be in the top ten.
>
> That's the long answer :)
>
> 73,
> Wayne
> N6KR
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> 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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