I would like to remind a point peculiar to GG amplifiers: there is an effect
called transferred power. Part of the drive power appearing at the input is
transferred to the amplifier's output and it gets summed up with the power
produced by the stage itself. This occurs because the power applied to the
input- apart from generating the driver voltage across the cathode
impedance- has nowhere to go but to the output through the tube. Since the
energy generated by the tube and the driver are in-phase they get added and
thus a percentage of the drive is actually transmitted. This is something
occurring only in grounded grid configuration and tends to compensate for
the lower μ resulting from the zero voltage on the screen. Besides, a GG
amplifier with a 4-1000 has a power gain of about 10-11 dB, less than what
it would give with a full complement of operating voltages, but more linear.
Alex 4Z5KS
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Dave white
Sent: Saturday, July 04, 2009 12:22 PM
To: RICHARD SOLOMON; Amplifier Reflector
Subject: Re: [Amps] 4-1000A in LK2000
Hi Dick
Just strap it to ground and treat it as the grid. Sure, it lowers the
amplification factor but if you have a modern 100 or 200 watt transceiver
who cares? I did consider rebuilding my amp as a true grid driven tetrode
amp like the circuit for the 4-400 that appeared in the early 1960s ARRL
handbooks but decided it wasn't worth the hassle. I suppose if - has a 10
watt K3 or similar then it'd be a different story....
Cheers
Dave G0OIL
-----Original Message-----
From: RICHARD SOLOMON <w1ksz@q.com>
Sent: 04 July 2009 04:29
To: Amplifier Reflector <amps@contesting.com>
Subject: Re: [Amps] 4-1000A in LK2000
Can I ask a dumb question ??
What do you do with the Screen Grid ?
Don't you need an additional screen supply ?
73, Dick, W1KSZ
> Date: Fri, 3 Jul 2009 20:26:01 -0700
> From: wc6w_amps@yahoo.com
> To: klahaie@centricata.com; amps@contesting.com
> Subject: Re: [Amps] 4-1000A in LK2000
>
>
>
> Hi Kevin,
> The input impedance of a 4-1000A in "strapped" grounded grid is circa 110
ohms.
>
> A 3-1000Z runs around 65 ohms.
>
> Some input network tweaking will be necessary with a transistorized
driver.
>
> 73 & Good evening,
> Marv WC6W
>
> http://wc6w.50webs.com/
>
>
> <snip>
> >
> > Is the input impedance that different from the 3-1000?
> >
> > 73 Kevin K7ZS
>
>
>
>
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