[AMRadio] sdr-iq


Rob Atkinson ranchorobbo at gmail.com
Sun Mar 28 08:51:30 EDT 2010


the Kenwood does indeed sound good for a s.s. ham transceiver; one of
the hams who does work on them heard from a kenwood engineer that they
had engineers from the kw audio products division working on the ham
gear and that's why among the JA gear kenwood has or had the
reputation for the best sounding audio.  I don't know about now though
because they have not produced any major ham rig in around 10 years.
The only time I use my 870 now is during times of rough QRM because I
can vary the passband down to 5 KHz and tune out a lot of the junk.

What I have heard lately from a friend who is interested in all this
digital stuff is that the dsp ham gear used to, or still does, employ
a technique called over sampling but this apparently led to digital
artifacts and degraded sound quality; the hot thing now is supposed to
be zero over sampling to correct this problem.  I don't know anything
about this; I'm just passing along what I have heard.  I have not sunk
any money into this because it seems like this year's hot item is next
year's "oh that's no good now, you have to get this..." so I'm waiting
but maybe you can use your SDR-IQ for the good part about digital, the
panadapter and other signal analysis but listen to the same signal
with an analog rx.    If you have your receiver feedline going to some
kind of splitter you could listen with an analog rx and use the SDR-IQ
for the analysis functions.

73

Rob
K5UJ

On Sun, Mar 28, 2010 at 6:58 AM, Bernie Doran
<qedconsultants at embarqmail.com> wrote:
> agree completly, after all these years I just wanted to have, great audio
> available, combined with numerous bandwidths for qrm. I hoped the sdr-iq
> would do that. the ft1000 is of course run to an external speaker, that
> little thing in there is so bad I used headphones for a while.  activating
> the dsp rips up the audio so much as to be unusable.  the HRO50-1  p-p 6V6
> that I have sounds very good and the sp600 is supposed to be the very best
> sounding.    if you KW has 24 bit then why would the sdr-iq use 14 bit?
> cheap cheap
> ----- Original Message -----
> From: "Rob Atkinson" <ranchorobbo at gmail.com>
> To: "Discussion of AM Radio in the Amateur Service"
> <amradio at mailman.qth.net>
> Sent: Saturday, March 27, 2010 11:43 PM
> Subject: Re: [AMRadio] sdr-iq
>
>
>> Hi Bernie,
>>
>> I have gone back and forth on the receive audio question with my rigs.
>> I have never had a PC controlled receiver, but I have a Kenwood TS870
>> which is a 24 bit dsp firmware receiver.  I have the 1000MP Mk V also
>> and I agree that the stock audio is not very good.  I widened the
>> stock 6 KHz passband AM IF and tapped the AM detector and brought that
>> signal out to an external tube push pull amp and speaker.  Those two
>> things made a vast difference on AM and it sounds like a tube boat
>> anchor rx now.  Next I get the 75A3 and fire it up and I'm not very
>> thrilled with the audio quality.  At this point the audio I get from
>> the stock TS870 with a 14 KHz passband is almost as good as the
>> modified Yaesu.  75A3 is worst of the three.  But I tap the detector
>> on the A3 and with a 10 KHz AM passband, put its audio out to another
>> p.p. vintage AF amp and set of speakers.  Now I prefer it over the
>> TS870 and it is at least as good or better than the tapped and
>> modified Yaesu.  I have never had a SX28 or any of the "audio" ba
>> receivers (many of which seem to be general coverage) but I have
>> concluded that most ham receivers need some help of one sort or
>> another as they were not intended for great audio but rather for
>> chasing dx.
>>
>> 73
>>
>> Rob
>> K5UJ


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