[AMRadio] sdr-iq


Bernie Doran qedconsultants at embarqmail.com
Sun Mar 28 13:22:33 EDT 2010


yep yep yep. I have several of those little solid state audio amps. $ 5 and 
half a dozen caps and resistors  near dc to channel 6 and unmeasurable 
distortion, whats not to like there?? does not get any better than those 
rascals.  I always wonder if anyone is using several of the bigger ones in 
bridge as a modulator.     well I know there is a TRICK to getting WINRAD to 
run. Do you intend to tell me and the others sometime in the near future?? 
or just let me continue to squawk?   rx sounds good, I sort of figured it 
was a minimalist rx for RF and IF. every circuit, every resistor and 
connection one puts in there adds junk to the signal.

---- Original Message ----- 
From: "Brett Gazdzinski" <Brett.Gazdzinski at verizon.net>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Sunday, March 28, 2010 12:40 PM
Subject: Re: [AMRadio] sdr-iq


> There is a trick to getting winrad to run, but its worth it for the audio,
> and changing the filters don't cause that racket, plus it does ecss which 
> is
> real nice.
>
> Also, how you listen to the audio likely counts, with spectravue, audio
> output is low and noisy, with winrad or sdr console its much louder and
> cleaner.
> With headphones off the laptop, it sounds fine, my laptop does not have a
> line out, only headphone output for feeding into the Marantz amplifier, 
> and
> does not sound that great that way.
>
> The sdr-iq is not great for operational use, since it has a lot of delay 
> in
> the computer, no muting, etc.
> It does make a good swl and listen only receiver for the price and size, 
> and
> is great for spectrum analysis of signals, even your own TX signal.
>
> Remember, the sdr-iq is the cheapest sdr you can buy that covers 100Hz to 
> 30
> MHz, they could have made it a LOT better for more money. The sdr-ip is
> better, and costs $3000.00 to start....
>
>
> The homebrew RX is a simple single conversion, 455 KHz IF no RF amp, for
> 160, 80 and 40 meters.
> No active stages before the mixer, just very high Q tuned circuits, the
> filters (Kiwa) is right after the mixer, some IF amp stages, a low
> distortion AM detector, agc, s meter, digital freq readout.
> All the tubes run off 150 volts, the LO runs off 100 volts.
> Its stable, accurate, quiet, has no birdies, image problems, and has very
> good fidelity.
>
> There are a lot of simple receivers that could be made much better, add a
> digital readout, and a kiwa filter board with say 6 and 8 Kc filters, and
> maybe re do the detector and agc, and you would have a very good AM
> receiver.
>
> I always wanted to try changing a 75s1 to hifi AM by adding a good filter
> and a good low distortion AM detector. It would be stable, accurate, with
> good AM filters, small and light, and nice looking, and still copy ssb and
> cw well.
> I suppose it could sound and work just as good as an R390a, sp600, and 
> other
> massive receivers, if you feed the detectors into a nice audio amplifier, 
> or
> build a nice hifi audio output stage, maybe using one of those 8 watt 5 
> pin
> audio output IC chips.
>
> Brett
> N2DTS
>
>
>
>
>
>
>
>
>
>
>
>
> ----- Original Message ----- 
> From: "Bernie Doran" <qedconsultants at embarqmail.com>
> To: "Brett Gazdzinski" <Brett.gazdzinski at verizon.net>; "Discussion of AM
> Radio in the Amateur Service" <amradio at mailman.qth.net>
> Sent: Sunday, March 28, 2010 7:39 AM
> Subject: Re: [AMRadio] sdr-iq
>
>
>> HI Brett: yep I have tried every setting that I can change. I have never
>> been able to get WINRAD to run and I do have the rf-space downloads to 
>> run
>> it. downloaded everything several times from different sources.  as I
>> said, the sdr filters work great, there is an anoying pop when you slide
>> the width around.   It is to the point that I have spent hours and hours
>> fooling with it and have seen no improvement since the first 2 hours.
>> sounds "OK" on SSB and its amusing to look at the splatting, residual
>> carriers and poorly suppressed upper sidebands on 80, most are good but
>> some really do not look good.  its best use is for a bandscope, test
>> equipment, or portable use, as you said.  Interested in your home brew rx
>> tell us what you have.
>> the 390 will fed its IF to a sync det and outboard audio stage at least 
>> as
>> a test.
>> ----- Original Message ----- >>
>>>> 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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>>
>>
>>
>
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