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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> > owner-tentec@contesting.com
> >
>
>
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