I use high plate voltage on my 4-1000a amps to lower drive required for a
given p/o. It`s very true that good tubes do not require huge amounts of
plate voltage,however most builders (first time constructors) get used tubes
that are so far gone that they raise plate and fil. voltages to get the last
bit of life from them.
There are a few things to look for when buying flea market tubes... Never
buy a tube from a guy if he said the fil checks good but he has no way to
check p/o.
(Unless you know the guy) Also, these things can look like they came out of
a fire (stained inside) and still be a high emission tube. There`s one thing
I have found after several years of buying used tubes ..... if you can see
multi-colors reflecting from the inside of the plate structure, you most
likely have a worn-out tube. I would welcome comments on picking and
choosing from other builders, please e-mail me direct to swap Ideas.
73 to all.. Jim K7RDX
----- Original Message -----
From: Terry Gaiser <w6ru@bak.rr.com>
To: Mike McCarthy, W1NR <w1nr@eecorp.com>; <amps@contesting.com>
Sent: Thursday, January 03, 2002 9:01 AM
Subject: Re: [AMPS] Building new 4-1000A amp
>
> I fully support the following comments regarding voltage and drive power
> versus power output of the 4-1000A .... have seen it myself several times
> with my amplifiers ... despite what the so called "experts" have reported
on
> here on several occasions.
> Terry W6RU
>
> ----- Original Message -----
> From: "Mike McCarthy, W1NR" <w1nr@eecorp.com>
> To: <amps@contesting.com>
> Sent: Thursday, January 03, 2002 4:27 AM
> Subject: RE: [AMPS] Building new 4-1000A amp
>
>
> >
> > Why does everyone insist that the 4-1000 needs in excess of 5kV to run
> legal
> > limit? I have built several that easily put out 1500W with only 4-4.5
kV
> > and 100W from a solid state rig. Am I just using good tubes vs. ones
near
> > the end of life? Probably.
> >
> > I would use bandpass coax stubs to keep harmonics down with only an "L"
> > network.
> >
> > Mike, W1NR
> >
> >
> > -----Original Message-----
> > From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> > Behalf Of Peter Chadwick
> > Sent: Thursday, January 03, 2002 3:59 AM
> > To: amps@contesting.com; 'wlfuqu00@uky.edu'
> > Subject: RE: [AMPS] Building new 4-1000A amp
> >
> >
> >
> > I used an L network in a marine tx many years ago: the antenna load for
> test
> > purposes in the 1.6 - 3.8MHz band was 10 ohms in series with 250pF, so
an
> L
> > network gave adequate harmonic rejection. The working Q came out at 15
in
> > that
> > case, so the losses were manageable. We sold several hundred of them, so
I
> > guess
> > they can't have been too bad.
> >
> > I gather from what's been said here in the past that you need 5 or 6kV
on
> > the
> > plate, but I guess you knew that already.
> >
> > 73
> >
> > Peter G3RZP
> >
> >
> > --
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> > Problems: owner-amps@contesting.com
> >
> >
> >
> >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/amps
> > Submissions: amps@contesting.com
> > Administrative requests: amps-REQUEST@contesting.com
> > Problems: owner-amps@contesting.com
> >
> >
>
>
>
> --
> FAQ on WWW: http://www.contesting.com/FAQ/amps
> Submissions: amps@contesting.com
> Administrative requests: amps-REQUEST@contesting.com
> Problems: owner-amps@contesting.com
>
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