Tim, the short answer is that usually a receiver described anecdotally as
"quiet" is a receiver that has inadequate gain. It should be possible to
hear receiver internal noise when the r-f and a-f gain controls are
advanced. If not, then that is usually a sign of a gain deficiency. There
should be enough gain in the system that the "front end" noise of the first
active device(s) can be heard in the absence of any signal.
However, and this is the other side of the coin, if one can hear a certain
noise level with the antenna disconnected, then connecting the antenna must
increase the noise level. If it does not, then the receiver has a problem
with excessive internal noise AND/OR there is insufficient gain to bring
the antenna noise up to a level that exceeds the internal noise level. In
either case, the receiver performance is deficient.
These are all qualitative and anecdotal terms. One man's "quiet" radio is
another man's radio that does not hear weak signals. Some people have a
great natural resistance to listening to noise, and they usually implement
this by reducing the r-f gain - which is actually the gain of the various
i-f sections - until most of the band and internal noise is gone. They are
willing to trade the ability to pick up the really weak signals for the
comfort of listening to the stronger ones.
Modern rigs such as the PRO with effective DSP noise reduction have changed
the game a lot and made it even more difficult to determine what "quiet"
really is. I recently worked a contest during a thunderstorm using my attic
antennas. The S-meter was hitting S9+30 db on noise peaks. Yet with the NR
cranked in at about 10 0'clock, the band sounded relatively quiet and even
the weak signals were workable.
You have raised an interesting question and I feel sure that my response is
likely to stir up a fair amount of discussion about the pros and cons of
"quiet" radios. But, having used most of them over the years, I have never
worked a really weak signal without having to work to bring it up out of
the noise.
73/72/oo, George W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
All outgoing email virus-checked by Norton Anti-Virus 2002
cyr999@extremezone.com wrote:
>
> Hi all -
>
> I find it quite interesting that Joe has aid the Jupitor is quieter. I have no
> way of knowing since I have never even seen a Jupitor. What I am REALLY
> curious
> about is how the phrase "Quieter" is defined. In one sense, if you hear
> nothing,
> a rig will be really quiet! On the other hand a rig could be quiet yet in
> doing
> so shut out some signals you'd really like to hear. I know I sound like a
> techno
> idiot, but I am beginning to wonder what "quiet" is. Anybody care to share a
> practical definition of a "quiet rig"?
>
> I have an interesting last two months which I feel has opened my eyes a bit.
> When I finally cleared up a few internal shack errors (with George's help), my
> 756 PRO ran circles around my OMNI V. A took me a little bit of time to sort
> out
> some problems that I created when I rearranged my shack upon getting the 756 -
> mainly ground loops and RFI. (One thing I did was hookup an external audio amp
> that is totally cool). Once my idiot mistakes were taken care of I could truly
> experience the 756 PRO. It is a phenomenal rig.
>
> Now don't get me wrong, I LOVED that OMNI V and I love TenTec as a company. I
> still do and always will. But I have to say that I feel I listened to the
> "crystals are the only way" theme for too long and it made me narrow minded.
> The
> 756 PRO is one terrific rig - no matter where it's made.
>
> Now here's the interesting part - once I learned how to use it and got used to
> the characteristics of a DSP rig, I realized my "quiet" OMNI was not hearing
> sigs the 756 was hearing. I know very little about interpreting the spec
> comparisons as shown on Elecraft's chart for all the major rigs, but I do know
> what I hear in the shack. So how do we define a "quiet" receiver?
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