[Amps] Audio BW, *WAS* Centurion cooling improvement ...

Joe Isabella n3ji at yahoo.com
Thu Aug 26 20:10:13 EDT 2004


This is a falacy.  My DSP rig does not allow any significant energy in the opposite sideband. 
However, when there is enough low frequency content, it can sound like a carrier when you tune
through the signal.  If there was a carrier, you would also hear it when there was no modulation,
which is NOT the case.  I know -- I have checked my signal with a spectrum analyzer.

This is the kind of incorrect information that creates bogus complaints and rules that we don't
need.  I suggest that anyone wishing to point fingers get a spectrum analyzer and look at their
own signals with their compressors cranked up overdriving their amplifiers.  Then talk to me about
4 or 6 kHz being too wide.

Joe,
N3JI

--- Frank Mayer <domino at worldlynx.net> wrote:

> Having bass that extends well below 100hz will cause a SSB signal to be wide by  modulating too
> close to the carrier point, crossing over onto the other sideband, and virtually turning into a
> DSB signal  If you don't believe this just try tuning a "hi-fi" guy in on using the AM mode. 
> The signal will be 100% intelligible!!  You can even hear the carrier when you tune across one
> of these signals.  Plus the fact when one tries to force over 10db of extra energy at very low
> or very high frequencies the IMD is terrific and that also contributes to the width of the
> signal.
> 
> WY3D
> ----- Original Message ----- 
>   From: Joe Isabella 
>   To: Amps 
>   Sent: Thursday, August 26, 2004 3:02 PM
>   Subject: Re: [Amps] Centurion cooling improvement ideas for AM service
> 
> 
>   Apparently, I'm one of "these morons".  However, be careful not to cast stones when you live
> in a
>   glass house, because "Bassiness" has nothing to do with the extended BW.  Only the high
>   frequencies take up the extra amount between 3 and 6 kHz.  I run out to 6k sometimes, but only
>   when there is enough space.  I'll continue to use my bottom end even if I only run out to
> 3.2kHz
>   or so.
> 
>   One other thing to keep in mind is that these rules only affect the US.  There are many
> Canadians
>   running 6k SSB (hence my moving to Canada comment), so don't expect all the 6k SSB to
> miraculously
>   disappear.  Their gov't allows 6k in the voice spectrum which is plenty.  I don't understand
> why
>   we have to put such strict limits on it.  
> 
>   Oh well -- I guess I'll keep on using AM at 9 kHz of bandwidth all the time istead of the 4 to
> 6
>   kHz that I would normally have been running on SSB.  Be careful what you ask for.
> 
>   Joe,
>   N3JI
> 
>   --- "Steven Grant, W4IIV" <stevengrant98 at yahoo.com> wrote:
> 
>   > the reason they are doing this is because some folks love to have very bassey audio. thier
> egos
>   > say that they must have broadcast quality audio.
>   > i dont think they will do away with AM or 10m FM
>   > i do believe that they need to limit SSB widths cause some of these "morons" insist on
> taking up
>   > bandwidth with a 5kc wide SSB signal
>   > steven,   W4IIV
>   > 
>   > "R.Measures" <r at somis.org> wrote:
>   > 
>   > On Aug 25, 2004, at 1:12 PM, Joe Isabella wrote:
>   > 
>   > > Prezactly... Except that it allows wider digital modes in the "CW" 
>   > > bands, and it limits SSB Voice
>   > > to 3 kHz. I'm not a big fan of this move by the League -- seems silly 
>   > > to put these limits in
>   > > place on voice. I think I'll move to Canada...eh??
>   > >
>   > Joe -- Letting the amateur radio community determine how a band is used 
>   > has worked well enough on 160m. The vast CW wasteland presently on 80m 
>   > is a good example of bad rule-making.
>   > end
>   > 
>   > > Joe
>   > >
>   > > --- Vic Rosenthal wrote:
>   > >
>   > >> R.Measures wrote:
>   > >>
>   > >>> Thanks, Joe. So this means that if adopted, 10m FM as well as AM 
>   > >>> will
>   > >>> be illegal.
>   > >>
>   > >> The bandwidth allowed in 29.0 - 29.7 MHz is 16 KHz.
>   > >>
>   > >> There is a specific provision to allow DSB AM in the 3 KHz areas:
>   > >>
>   > >> "(1) The 3 kHz maximum bandwidth does not apply to double-sideband
>   > >> amplitude-modulated phone A3E emissions which are limited to --26 dB
>   > >> bandwidths of 9 kHz."
>   > >>
>   > >> You can read the whole thing at:
>   > >>
>   > >> 
>   > >>
>   > >> It's not going to make any revolutionary changes.
>   > >>
>   > >> -- 
>   > >> 73,
>   > >> Vic, K2VCO
>   > >> Fresno CA
>   > >> http://www.qsl.net/k2vco
>   > >>
>   > >>
>   > >> _______________________________________________
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>   > >>
>   > >
>   > >
>   > >
>   > > 
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>   > >
>   > Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>   > 
>   > _______________________________________________
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>   > 
>   > 
>   > 
>   > STEVEN GRANT    W4IIV
>   > 
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