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
>
>
> --
> FAQ on WWW:
> http://www.contesting.com/FAQ/tentec
> Submissions: tentec@contesting.com
> Administrative requests:
> tentec-REQUEST@contesting.com
> Problems:
> owner-tentec@contesting.com
>
__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/
--
FAQ on WWW: http://www.contesting.com/FAQ/tentec
Submissions: tentec@contesting.com
Administrative requests: tentec-REQUEST@contesting.com
Problems: owner-tentec@contesting.com
|