Well what this points to is the inability of most ham radio
manufactueres to deliver a decent total solution. G3SEK will probaly
disagree, but here goes
A TRANSMITTER WITH A 3RD order IMD OF -40 DB
A RECEIVER WITH A THIRD ORDER INTERCEPT POINT OF +30DBM
THE RECEIVERS RECALIBRATED TO THE COMMERCIAL STANDARD SO WE CAN
MEASURE ANTENNAS AND POWER ACURATELY, THIS WAS SUGGESTED BY DR RHODE IN
QST
When we achieve this we can then talk about more power. Look at the
problems that station like GI0AIJ and N7ML have with stations
complaining constantly about splatter and illegal power etc. When in
reality the complaining stations receivers cant cope, and likewise the
transmiters are well within spec but at the signal levels the stacks
generate it sounds terrible since 30 db down from beeing 50db over S9
is not all that much. Also at this signal level you will start hearing
the 5th order products quite well. We must remember what we can do with
QRP power, so these odd order products are beeing sent across the ocean
that are signal strength 6 or there abouts.
You would think a DSP radios like the Kachina or the New Ten tec could
have had this high performance market to themselves, yet they chose to
deliver a mediocre product that have performance figures from the late
seventies. So much for progress
Igor
--- Tom Rauch <w8ji@contesting.com> wrote:
>
> > Somehow I wish more people would run tubes
> like 4CX5000 or
> > 4CX10000 or similar, think we would have
> less splatter and
> > cleaner/nicer sounding signals on the band.
>
> > These days we have rigs with very big power
> spikes that flat
> > tops the amplifiers and also people that
> drives the crap out of
> > their 1500 W amps to make them deliver a
> puny 350 Watts more. Take a
> > good listen to the SSB signals of today, at
> least 75% of
> > them
> > flat tops or doesn´t sound right.
>
> Maybe, but then we must also think of all the
> wonderful signals
> that would come from grid driven tetrodes with poor
> screen or bias
> regulation.
>
> Grounded grid triodes, if properly tuned, enjoy the
> benefit of heavy
> negative feedback. That feedback makes for very
> clean
> amplifiers.The proper way to tune a grounded grid PA
> is to actually
> OVER load the PA slightly, and then reduce power in
> operation.
>
> A better way to reduce splatter is to educate the
> idiots who turn up
> the internal power controls of their rigs, in a
> CB-like manner. Most
> radios are very poor IMD performers both at very low
> and very high
> power. Many tetrode amps wrongly suggest that
> running a 100
> watt radio at 10 or twenty watts makes a cleaner
> signal, that isn't
> true at all. The opposite is actually true.
>
> While a babied overkill properly designed tetrode
> might be OK,
> there is just too much to go wrong in the hands of
> people who can't
> load a triode. Either PA, especially the GG triode,
> would be cleaner
> then the radio anyway.
>
>
>
> > 73, Jim SM2EKM
> >
> > PS: I have one brand new 4CX10000 and one
> brand new 4CX15000 for
> > sale, anyone interested?
> >
>
------------------------------------------------------------------------
> > ----------------------------------------
> >
> > -----Ursprungligt meddelande-----
> > Från: measures@vc.net [SMTP:measures@vc.net]
> > Skickat: den 9 juli 1999 04:52
> > Till: amps@contesting.com
> > Ämne: VB: RE: [AMPS] 4cx10000
> >
> >
> >
> >
> > >
> > >
> > >>
> > >> My favourite tube. My question is this, how
> many times can you
> > rebuild
> > >> 8171s before they are tired and worn. Never
> having to do this i
> > always
> > >> wonder about the value of people like Econco. I
> have a good supply of
> > >> these tubes myself so have never had need to
> rebuild one. I have a
> > few
> > >> that are shot as well mainly using them for
> door stops.
> > >>
> > >
> > >Econco have repeatedly stated the 8171 and
> similar tubes could be
> > rebuilt
> > >essentially forever since the anode can be
> removed without loss of
> > metal.
> > >In those tubes which require cutting the
> ceramic-metal seal the limit
> > is
> > >the care with which the seal is cut and amount of
> material that is
> > lost.
> >
> > ? The metal/ceramic bond is silver-solder. The
> anode can be
> > unsoldered
> > as easily as it is soldered.
> >
> > >Once too much material is lost (two, three or
> four generations in most
> > >tubes) the tube is unrebuildable due to the
> cahnge in parameters.
> > >
> > >With the 8171, I suspect a good "pull" will last
> a lifetime with, at
> > >most, one rebuild in amateur service as long as
> the amplifier is built
> > >with suitable regulation and safety circuits.
> > >
> > >73,
> > > ... Joe Subich, W8IK/4 ex-AD8I
> >
> >
> >
> > Rich...
> >
> > R. L. Measures, 805-386-3734, AG6K,
> www.vcnet.com/measures
> >
> >
> > --
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> http://www.contesting.com/ampfaq.html
> > Submissions: amps@contesting.com
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> > Problems:
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> > Search:
> http://www.contesting.com/km9p/search.htm
> > <<Fil: RE_ [AMPS] 4cx10000.TXT>>
> >
> >
> > --
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> >
> >
>
>
> 73, Tom W8JI
> w8ji@contesting.com
>
> --
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>
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