[AMRadio] sdr-iq

Bernie Doran qedconsultants at embarqmail.com
Sat Mar 27 13:13:48 EDT 2010

well I am going to stir the pot again with my probable final comments on my 
SDR-IQ.  first the good, never had a panadapter or bandscope, it works great 
for that. The filters are very good.  The issues to me are the following, it 
is noisy, to itself and also to a receiver on the same antenna, it lacks 
sensitivity, it has spurs,  and the big one to me is the audio quality, a 
moderate strength AM signal is difficult to understand and when on my hollow 
state stuff it is nearly %100 copy.  The present computer is a 2.2gig quad 
core, no performance change above a single core 1.8 gig.   Numerous 
different audio systems confirm that it is the nature of the beast.

I have read numerous articles on D-A and A-D processing and believe that 14 
bit is not going to do the job that I want.  I suspect 24 bit and a much 
higher sampling rate, 150 meg?  would just about cure the audio issue for 
me.  I am starting to believe that the glowing reports written about SDR are 
prepared by those that have never used an old VT receiver or have one 
available to run beside the sdr. My FT1000 Mark V had glowing reports and I 
am really disappointed with it.  I have an ever deepening respect for those 
that designed and built the old classic receivers.  Looking at noise figures 
and sensitivity on those old dogs places them very close to theoretical 
limits, pretty amazing.  I have put my money where my mouth, I should, about 
April 10 or so have a completely reman R-390A.   I was going to try the Flex 
5000, but as I posted earlier they did not see fit to respond to my 
questions, perhaps  thinking the questions were not fit to respond too.

Earth hour is today, be sure to turn on all of your lights to help save the 
grid and generators.  !  Bernie W8RPW 

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