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" <n...@elecraft.com>
To: "J. Fielden" <gijoe1...@gmail.com>
Cc: <elecraft@mailman.qth.net>
Sent: Friday, January 29, 2016 6:55 AM
Subject: Re: [Elecraft] Kx3 receiver
J. Fielden <gijoe1...@gmail.com> 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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