[Amps] Centurion cooling improvement ideas for AM service

Thu Aug 26 16:44:50 EDT 2004

     With easing up on the requirements to get a HF license. It is becoming 
more and more difficult to find a spot to operate. Some would interpret 
6KHz bandwidth limit for SSB to mean that splatter is acceptable.  3 Khz is 
sufficient band width to communicate by voice. In fact telephones have been 
built using the 300 to 3000 Hz band width ( or there about) as being 
sufficient for all voices but
perhaps not music.
     6 kHz on SSB would be greater audio bandwidth than used for standard 
AM broadcast (5kHz). Which was adopted to accommodate music broadcast.
    The other side to using 6kHz for SSB in particular on the receiving end 
would require twice the  transmitted power to accomplish the same signal to 
noise as compared to 3khz. And 3 times the tx power than when using 2kHz. 
So the minimum power rule enters in as well.
     Using twice the bandwidth than necessary just does not make sense.
     What I don't understand is the use of independent sideband. What does 
ISB have to do with ham radio. It was used for long distance phone 
communications before undersea cables and satellites to either transmit two 
or more channels or for secure transmissions. Are we going to transmit 
stereo? If so it seems to be a waste of bandwidth.
     Also, mixing automated digital modes and voice or manual CW is a bad 
mistake. For example a PSK 31 station observing a CW station would perhaps 
think that he is not going to interfere with it and go ahead and transmit 
only 50 or 100 Hz from the CW stations frequency. Or a CW station may think 
that a PSK31 station was just a birdie or some other obnoxious signal that 
was not a ham station if he did not have a means of monitoring (a computer 
and such). You can hear the modulation on a PSK31 signal if you have 
sufficient signal strength. But other wise it may just sound like some 
other spurious signal produced by the numerous microcontrollers in the 
neighborhood.
    The accepted minimum bandwidth for CW 3 times the dit rate (2.5 times 
WPM= Hz bandwidth)  the word rate. The theoretical limit is actually the 
dit rate but it is difficult to copy with out using a computer at that 
narrow of a bandwidth (this is easy to prove mathematically). So 11 or 12 
WPM would take up the space of 1 PSK31 signal if we limited the rise and 
fall time of the transmitter to what would be necessary. Or if you used a 
computer to copy, the speed of OOK (CW) could be raised to over 20 wpm but 
to limit the TX bandwidth to the real bandwidth limit would require more 
than a key click filter. Just limiting the rise and fall times to some 
value will not do it. This is another story entirely. You might call it 
SSBCW with Carrier.

     My fear is that if we persist in setting HARD limits in bandwidth and 
such we will finally end up with the HF bands defined as channels (like 
60meters) and require everyone to use "Standardize radio equipment". This 
would prevent lots of experimentation and learning by young and old ham.  I 
would like one change, after giving it much thought. That is, to allow HF 
amplifiers to be manufactured that  can be driven by low power 
transmitters. This allows QRP operators/experimenters  to easily purchase 
QRO equipment. It is OK as long as there are provisions for not allowing 
amplifiers to be sold to non-HF-hams.

73
Bill wa4lav


At 12:02 PM 8/26/2004 -0700, Joe Isabella wrote:
>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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