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[TenTec] IC-7800

To: <tentec@contesting.com>
Subject: [TenTec] IC-7800
From: btippett@alum.mit.edu (Bill Tippett)
Date: Sat May 17 09:33:09 2003
         The only spec that caught my eye was:
"+40dBm ultra high intercept point ", but they neglect
to say what signal spacing or with what attenuation
this is specified for.

More info here:

http://www.qsl.net/kk5dr/rumors.html

and here:

http://www.qsl.net/kk5dr/ic785_architecture.htm

Note especially:

"70 MHz 1st IF with 15 kHz-wide roofing filters ->
down-converter to 455 kHz 2nd IF/noise-blanker

with 15 kHz-wide  roofing filters ->

down-converter to 100  kHz final (DSP) IF ->

  32 bit ADC -> 32 bit DSP ->  32 bit DAC ->

audio amp.

It has been conjectured that the "785" will employ a 100+ Khz DSP I.F., the 
current PRO II employs a 36Khz DSP I.F. a large difference...  (Further 
research confirms that this is highly likely in the production units of the 
"785".) The recent rumor confirmation included that the DSP IF will likely 
run at 136 KHz."

         Sounds like more DSP hype by folks who don't
fundamentally understand the need for a strong analog
signal path prior to reaching the DSP.  If the IC-785/7800
uses 15 kHz roofing filters at first and second IF stages,
the Orion will beat the socks off it in close-spaced IMDDR3,
BDR, IP3, etc...just as it will every other radio using a
similar  IF scheme (i.e. FT-1000MP, IC-756PRO2, etc.)

                                 73,  Bill  W4ZV

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