Al:
You are absolutely correct. I wish the other folks understood this
fact.
73
Bob K4TAX
LORONAAL A-USAex3 wrote:
>
> Hi, Everybody,
>
> An interesting discussion. Practically, I can understand those who say they
> don't care about a spurious tone in the audio output that is so far down
> that it cannot interfere with normal communications. Practically, that's
> absolutely true. Virtually all radios have by-products, birdies, audio
> intermod, phase noise, and other junk if you look closely enough. On the
> other hand, Larry (VA3LK) is perfectly right to say that, for his extreme
> weak-signal work, the distortion can't be tolerated. In the worst case I
> suppose it would fool his decoding software into thinking that there were a
> very weak signal there, when there really weren't! And that would be bad.
>
> What an interesting test, to put a spectrum analyzer on the audio output and
> show the result in the product reviews. I'd like to see that.
>
> R,
>
> Al W6LX
>
> -----Original Message-----
> From: Jim Cox [mailto:jcox@digitalexp.com]
> Sent: Wednesday, June 27, 2001 6:54 AM
> To: Duane Grotophorst; dslosty; tentec@contesting.com
> Subject: Re: [TenTec] ARRL product review test change
>
> If you have to turn the volume up 100 percent to hear it, why worry about
> it? How many of us run our radios at 100 percent volume?
> I bet if you ran your car at 100 percent you'll hear some strange noises
> too.
>
> ----- Original Message -----
> From: Duane Grotophorst <n9dg@yahoo.com>
> To: dslosty <dslosty@pipeline.com>; <tentec@contesting.com>
> Sent: Tuesday, June 26, 2001 10:44 PM
> Subject: Re: [TenTec] ARRL product review test change
>
> >
> >
> > I would like to see the ARRL add a product review test
> > where they show the audio output spectrum of the RX
> > audio passband with a 50-ohm load on the RX input.
> >
> > With today's digitally based radios (DSP IF or
> > otherwise) there is a potential for, and frequently
> > is, extraneous noises and other artifacts in the RX
> > audio signal.
> >
> > At the risk of re-opening old heated debates here on
> > the reflector, I have also seen the persistent tone in
> > the middle of the RX filter passband the Larry, VA3LK
> > saw with the Pegasus. It is actually quite easy to
> > see, I used SR5 Spectrum Analyzer program (from
> > www.ar5.com) to look at the audio passband. I can also
> > see it on the waterfall display of the PSK31 program I
> > use. In fact both of the Peg's I have exhibit the
> > exact same behavior. That tone is actually audible if
> > you crank up the volume 100%. For what its worth
> > though, the fact that you can turn the volume up all
> > the way and not be driven out of the room by white
> > noise is a testament to what Ten Tec has done well
> > with their RX design.
> >
> > Anyone who is already wired up to do PSK31 or any of
> > the other "sound card" modes, can simply download any
> > number of freeware spectrum analyzers and look at the
> > audio signal of you RX. I've used both SR5 and
> > Spectrogram for my tests; I'm sure there are others.
> >
> > I haven't turned the audio spectrum analyzer loose on
> > my other radios yet, but I do expect to find some
> > interesting things. Bottom line is that whatever
> > internally generated noises or other artifacts that
> > may appear in the RX audio passband are actually every
> > bit as important as all of the dynamic range and phase
> > noise measurements that product reviewers are so
> > focused on.
> >
> > 73,
> > Duane
> > N9DG
> >
> > --- dslosty <dslosty@pipeline.com> wrote:
> > >
> > >
> > >
> > > I don't know if this has been mentioned on the
> > > reflector but I
> > > found the changes announced in July's QST
> > > interesting.
> > >
> > > The League is now going to use a 5KHz standard
> > > spacing versus the
> > > former 20 KHz spacing while testing receiver dynamic
> > > range
> > > and intercept points. This should better
> > > characterize crowded band conditions.
> > >
> > > On page 80 of July's QST is a listing of several
> > > current HF
> > > transceivers. According to the new tests, the
> > > Elecraft K2 and
> > > the Ten-Tec Omni 6+ have far better figures than the
> > >
> > > IC-756PRO, FT-1000MP, etc.
> > >
> > > Of course, most of us already knew this.....
> > >
> > >
> > > 73,
> > > Doug/WA1TUT
> > >
> > >
> > > --
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> > >
> >
> >
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> >
> >
>
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