Hi Bill,
I know the website. It seems devoid of any pricing or availability
information for some reason.
The amps look very much like several of my homebrew projects, so that
doesn't bother me.
I wonder if these amps are FCC Certificated? If so, I would think the
company would publish that information, as it's quite valuable. If not,
they shouldn't be selling them at all....
73,
Steve, WB2WIK/6
"If everything seems under control, you're just not going fast enough." -
Mario Andretti
> -----Original Message-----
> From: Bill Smith [SMTP:ko4nrbs@yahoo.com]
> Sent: Tuesday, September 24, 2002 9:29 AM
> To: Steve Katz
> Subject: RE: [Amps] 4CX250F Tubes
>
> Here is their web site:
> http://www.cticomtec.com/
>
> I think I will keep looking until I find a well built
> homebrew or something I can easily convert. I don't
> have time to build on myself.
> 73,
> Bill
> --- Steve Katz <stevek@jmr.com> wrote:
> > Hi Bill, see below...
> >
> >
> >
> > > Thanks Steve. I thought I might have a new top
> > cover
> > > made for the Mark 1 that is tall enough. A friend
> > of
> > > mine owns a metal working shop and told me he
> > could
> > > get to it in a day or two depending on how
> > elaborate I
> > > wanted it. May be the way to go. New 3-500Z
> > tubes
> > > would outlast me if I take care of them.
> > >
> > > I like the new CTI PLA800 amp that uses two
> > 4CX250B
> > > tubes. Heard anything about it?
> > >
> > [Steve Katz] Yes, I have, but I've never seen one.
> > The claims made
> > seem inappropriate for the design indicated, at
> > least to me. I wonder how
> > they get "1200W PEP" output power from a pair of
> > 4CX250s running at 2000V
> > and 600mApk-? Seems to me that's 1200W input power.
> > And the use of two
> > little axial fans blowing against the backpressure
> > of the 4CX250s and its
> > enclosure/output grille, etc, doesn't seem
> > sufficient, regardless of claims.
> > I've always used centrifugal blowers for these
> > tubes, the backpressure is
> > very high, much higher for the 250B design than for
> > the old 150A. But,
> > again, I've never seen one up close, and would love
> > to. -WB2WIK/6
> >
> > > 73,
> > > Bill
> > >
> > >
> > > --- Steve Katz <stevek@jmr.com> wrote:
> > > > Hi Bill,
> > > >
> > > > Lots of 4CX250B amps out there, all you need to
> > do
> > > > with the "F" is change
> > > > the filament transformer.
> > > >
> > > > I modified a few Mark I (and other) amps using
> > > > 3-400Zs to 3-500Zs without
> > > > making the chassis covers any taller...just sunk
> > the
> > > > sockets down below the
> > > > main chassis level, so the 3-500Zs sat lower in
> > the
> > > > amp. That's not
> > > > difficult to do with the Mark I, but if you do
> > so,
> > > > you need to make sure
> > > > there's airflow across the filament pins. If I
> > > > recall correctly (it's been
> > > > about 20 years), I just added another fan under
> > the
> > > > chassis, blowing on the
> > > > tube sockets.
> > > >
> > > > 73,
> > > >
> > > > Steve WB2WIK/6
> > > >
> > > > "If everything seems under control, you're just
> > not
> > > > going fast enough." -
> > > > Mario Andretti
> > > >
> > > > > -----Original Message-----
> > > > > From: Bill Smith [SMTP:ko4nrbs@yahoo.com]
> > > > > Sent: Tuesday, September 24, 2002 8:35 AM
> > > > > To: Steve Katz
> > > > > Subject: RE: [Amps] 4CX250F Tubes
> > > > >
> > > > > Thanks Steve. I may forgo the idea and just
> > use a
> > > > > couple of 3-500Z tubes by cutting a hole in
> > the
> > > > top of
> > > > > the enclosure and install a nice screen mesh.
> > > > >
> > > > > I think I will look for an amp that uses
> > 4CX250B
> > > > > tubes. They are cheap and easy to find!!
> > > > > 73,
> > > > > Bill
> > > > > --- Steve Katz <stevek@jmr.com> wrote:
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > > >Just came in to possession of a box full
> > of
> > > > new
> > > > > > > >4CX250F tubes. Thought they may be a
> > very
> > > > low
> > > > > > cost
> > > > > > > >alternative to the 3-400Z tubes in my
> > Swan
> > > > Mark 1
> > > > > > amp.
> > > > > > > > I know it would take quite a bit of work
> > to
> > > > do
> > > > > > but I
> > > > > > > >would be in tubes for the rest of my
> > life!!
> > > > > > > >
> > > > > > > >Can these tubes handle the 2500vdc the
> > Swan
> > > > puts
> > > > > > out?
> > > > > > >
> > > > > > > On SSB/CW, yes.
> > > > > > >
> > > > > > > >I know they are rated at around 2000vdc
> > plate
> > > > > > voltage.
> > > > > > >
> > > > > > [Steve Katz] I've used 4CX250F's in VHF
> > PAs
> > > > with
> > > > > > great success.
> > > > > > Because they have full gain/output up to 400
> > > > MHz,
> > > > > > they might make great
> > > > > > oscillators when used in an HF amp unless
> > new
> > > > > > precautions are taken. And,
> > > > > > obviously, two of them (one each to replace
> > > > 3-400Z)
> > > > > > won't run nearly the
> > > > > > power of the original tubes...it would take
> > four
> > > > to
> > > > > > do that. I've never
> > > > > > used 4CX250's in grounded grid. They
> > require
> > > > > > "bottom to top" cooling,
> > > > > > pressurized, with air system sockets and
> > > > chimneys.
> > > > > > Guess you could make a
> > > > > > big metal plate to cover the original socket
> > > > holes
> > > > > > and punch that for the
> > > > > > SK600 series sockets.....-WB2WIK/6
> > > > > >
> > > > > >
> > > > > > > >73,
> > > > > > > >Bill
> > > > > > >
> > > > > > >
> > > > > > > - R. L. Measures, a.k.a. Rich...,
> > > > > > 805.386.3734,AG6K,
> > > > > > > www.vcnet.com/measures.
> > > > > > > end
> > > > > > >
> > > > > > >
> > > > _______________________________________________
> > > > > > > Amps mailing list
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> > > > > > >
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> > http://lists.contesting.com/mailman/listinfo/amps
> > > > > >
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> > > > > >
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> > http://lists.contesting.com/mailman/listinfo/amps
> > > > >
> > > > >
> > > > > =====
> > > > > Bill Smith KO4NR
> > > > >
> > > > >
> > __________________________________________________
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> > >
> > > =====
> > > Bill Smith KO4NR
> > >
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> === message truncated ===
>
>
> =====
> Bill Smith KO4NR
>
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