[AMPS] RE: 4cx10000
Tom Rauch
W8JI@contesting.com
Sat, 10 Jul 1999 07:39:42 -0400
> 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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>
73, Tom W8JI
w8ji@contesting.com
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