[Elecraft] Icom IC-7300

[Wayne Burdick]

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 <w7ox at 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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