Phil,
4CX15000 is a tetrode whose single tone power output is theorically 36 Kw,
as per Eimac data sheet., but the obtainable power by such kind of tubes is
generally much less when talking about continuous carrier level.
Often, the real curves of the tubes differ consitently from those deductable
by the graphic of constant current
ones on data sheets, and a single tone power is a different story than a
carrier level.
Saying it in other words, in a conventional class C final stage AM
transmitter useing with a single 4CX15000 the carrier should be one fourth
of max peak power to reach the claimed 36 Kw on the AM peaks.
In other modes like FM, a wattmeter wouldn't read ever 36Kw of carrier power
because that level is well over the tube capability and (reasonable) gain
already went away at much lower carrier output.
Let's suppose reasonable a 10 dB gain to have 15 kW for each tube, the
required drive power would be 1.5 Kw and the claimed 3 x 8877 could largely
meet requirements for 30Kw (two tubes).
Never, (even overdriving a lot) is possible to get twice that output (60Kw)
in term of carrier power with that configuration and those tubes.
Last but not least, a 10Kv tube operated @ 14Kv has yes a bigger gain and
output (30-40%) but a much
bigger probability of internal flashes. Statistically, in a parallel of 3
tubes the flash is nearly sure each time the full driving power is applied.
Another point, a tetrode operated in GG doesn't differ substantially from a
triode in term of efficiency and 3 x 8877 would be a total nonsense in a
grid driven amplifier.
All the story looks as the fishermans' story (the real fish is much smaller)
or as something developed by someone with electronic bases but following
conventional behaves and the readings of data sheets rather than a mere
report of real facts.
Concerning the reported corona effects, they may happen at nearly any power
depending by used antennas
and enviromental conditions.
73,
Mauri I4JMY
-----Messaggio Originale-----
Da: Phil LaMarche <plamarc1@tampabay.rr.com>
A: Maurizio Panicara <i4jmy@iol.it>
Data invio: giovedì 14 ottobre 1999 16.32
Oggetto: RE: [AMPS] You gotta read this....
> Murry,
>
> Unfortunately the facts are real. I saw that person at a ham fest and
> witnessed what they claim.
>
> Phil W9DVM
>
> > -----Original Message-----
> > From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> > Behalf Of Maurizio Panicara
> > Sent: Thursday, October 14, 1999 10:17 AM
> > To: Phil Levin W2GE; amps@contesting.com
> > Subject: R: [AMPS] You gotta read this....
> >
> >
> >
> > I don't know if laughing more to the claimed amplifier structure and
> > performances or to who believes it.
> > (repost this message next april 1st)
> >
> > 73,
> > Mauri I4JMY
> >
> >
> >
> > -----Messaggio Originale-----
> > Da: Phil Levin W2GE <w2ge@home.com>
> > A: <amps@contesting.com>
> > Data invio: giovedì 14 ottobre 1999 2.04
> > Oggetto: [AMPS] You gotta read this....
> >
> >
> > >
> > >
> > > I'm quoting without names a message from what our CB brethren are up
to.
> > >
> > >
> > > "Take for instance...
> > >
> > >
> > > 2X4CX15,000 being driven by 3X8877
> > > Ep was close to 14 kV on the 15,000s....
> > >
> > > Power output was capable of over 80,000 watts Bird. Tuning it up,
with
> > > a
> > > 1 kW slug in the Bird meter for reverse measurements, we couldn't get
it
> > > to
> > > wiggle up to 40 kW forward output. At the 44 kW mark (or
thereabouts),
> > > we
> > > blew the top of the antenna off, a nice blue corona came, and the
> > > antenna
> > > spit flames! Nice, to say the least. The tubes are run Class C, and
> > > tetrodes are the tube of choice. What with screen volts, you get
better
> > > efficiency. Just have to keep those grids biased WAY negative, and
you
> > > can
> > > live with the higher plate voltage.
> > >
> > > After that, we went to a "fighting stick" (Quarter wave, usually made
> > > from
> > > 3/4 inch copper pipe, chrome plated) and we where able to tune the amp
> > > to
> > > 75 kW. It still had more to go, but that was where we left it for a
> > > competition. This was the inaugural run of the amp.
> > >
> > > You might wonder where the power comes from for one of these beasts
(and
> > > this is smallish. The last one that I saw perform (over 4th of July)
> > > was
> > > capable of nearly 125 kW Avg. output)).
> > >
> > > Usually it is a big block motor, using alternators made by the
> > > Electrodyne
> > > company. They are designed as Locomotive Braking motors, but run with
a
> > > small voltage on the field, they will act as an alternator... They
are
> > > dual
> > > stator, single rotor, producing 60 volts at 600 amps each stator, run
> > > full
> > > field. Run 5 to 7 of these.
> > >
> > > Engine: Large stroke, large bore with Nitrous is the name of the
game.
> > > Typically see 500+ horsepower.
> > >
> > > So, you see, the CB community has really started going nuts. I don't
> > > agree
> > > with the power levels run, but that is what the market "demands".
> > >
> > > Like I said, if you want a good "big picture" scene, look at
> > > www.bigradios.com/shadow... Come see what us goofy CBers are doing.
> > >
> > > I had one blow the high voltage power supply from my video camera.. I
> > > was
> > > about 100 yards away... This was from near field radiation picked up
by
> > > the
> > > power lines."
> > >
> > >
> > > Oh Boy, Phil W2GE
> > >
> > > --
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> > > Submissions: amps@contesting.com
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> > > Problems: owner-amps@contesting.com
> > > Search: http://www.contesting.com/km9p/search.htm
> > >
> >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/ampsfaq.html
> > Submissions: amps@contesting.com
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> > Problems: owner-amps@contesting.com
> > Search: http://www.contesting.com/km9p/search.htm
> >
>
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