Thanks for the explanation, Wayne. Funny thing is
that I never think of the K3 as *functionally* an
SDR radio, I guess because I don't have access to
the I/Q signal -- unless it accessible in some
sneaky way I don't know about. OTOH in principle
it seems one could take the I/Q output of the KX3
and build their own "back end", playing all sorts
of games -- not that I plan such an adventure.
However, last Summer I did build one of the Tiny
Python Panadapters in the April 2014 QST which was
a fun project made possible by the KX3's I/Q port,
though I soon replaced it by the much more capable
PX3.
Aside from its "cosmetic" features, which don't
particularly appeal to me, the Icom-7300 looks
like a radio not well suited for operation in
crowded bands, DX pile-up situations, a
strong-signal environment or Field Day. It will be
interesting to see what the QST and Sherwood tests
reveal.
There are some SDR dongles which will provide a
"look at multiple MHz of bandwidth" at very low
cost :-) Such a capability can be useful in
monitoring a band you're not currently operating.
73, Phil W7OX
On 9/3/15 3:47 PM, Wayne Burdick wrote:
Hi Phil,
Just to clarify: Both the KX3 and K3/K3S are SDRs. A major difference between
these rigs and something like the IC-7300 or Flex 6xxx series is that our
A-to-D converters (ADCs) are protected from wideband interference by a
narrowband I.F. The K3/K3S uses crystal filters, while the KX3 uses precision,
narrowband low-pass filters.
In direct-sampling SDRs, the ADC is right at the front end of the radio,
protected only by wideband LC filters. The result is typically 15-20 dB lower
blocking dynamic range. More subtle is the effect of multiple signals, which
can combine in phase to hit the limit of the ADC, resulting in unwanted images.
It's a tradeoff; a direct-sampling SDR can allow you to look at multiple MHz of
bandwidth on its spectrum display, if that's of interest.
Wayne
N6KR
On Sep 3, 2015, at 2:57 PM, Phil Wheeler <w...@socal.rr.com> wrote:
Joe,
Thanks for addressing what to me is the core issue with any rig -- performance. A
"bells and whistles" user interface -- and that can be a matter of personal
preference -- may sell a lot of rigs, but to me performance is key in selecting a base
station transceiver. I can compromise performance for special applications like portable
ops, QRP, etc. but I want my main station radio to be near the top of the list in the
Sherwoodian sense.
After looking at the information here
http://www.icomamerica.com/en/products/amateur/hf/7300/default.aspx an in the
pdf file linked here:
http://www.icomamerica.com/en/downloads/DownloadDetails.aspx?Document=746
and from the general appearance of the Icom-7300 (ports, controls, etc.) I don't expect
it to be near the top when Rob Sherwood tests it. Of course, it hinges on a number of
factors -- including those you brought up below -- and I could be surprised. Even so,
while I'm not spring-loaded against SDR rigs (the KX3 is basically an SDR radio, after
all, and I enjoy mine), I can do without a touch-screen interface. But I've been at this
for 62 years now, so maybe I'm just "old fashioned" :-)
73, Phil W7OX
On 9/3/15 1:39 PM, Joe Subich, W4TV wrote:
I think this is Icom's way of dipping their toe in the water and not
upsetting their fan base by introducing an SDR in convention looking
hardware. I am confident that they will be releasing a whole line of
stand alone SDR rigs...
The question will be what quality ADC Icom uses in the front end of the
7300 and how clean (phase noise) they can make the synthesizer (clock).
If they have enough ADC bits to provide dynamic range, their claimed
synthesizer phase noise comparison should put the 7300 at about the
same level as the Ten-Tec Eagle in the Sherwood "chart" (e.g., 92-95
dB IMDDR3, -134 dBc @ 10 KHz phase noise, 125-130 dB 100 KHz blocking
[ADC limited]).
If Icom "cheaps out" and uses an ADC with limited resolution (number of
bits) like some of its commercial products, the 7300 is likely to fall
way down the list - into the neighborhood of the IC-7000 or FT-2000.
73,
... Joe, W4TV
On 9/3/2015 3:19 PM, Wm Robert Leschyna wrote:
Personally I feel that a touch screen is a must in a "stand alone" (no pc
needed) SDR, as it allows the future development and or creation and use of
soft keys for functions that we may not even think of today. As for the
IC7300, most of the time you will likely be using the most commonly used
functions which appear to be tied the physical knobs and buttons, and not
have to touch the screen that much.
SDR is the way of the future, heck it is the way now, and I think this is
Icom's way of dipping their toe in the water and not upsetting their fan
base by introducing an SDR in convention looking hardware. I am confident
that they will be releasing a whole line of stand alone SDR rigs...
I have owned a K2 a couple K3s and KX3, I love Elecraft and love supporting
a made in North American brand, but frankly am confused as to why Elecraft
isn't leading the pack on stand-alone SDR?
73
Bob
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