This guy used a series screen regulator and a fuse also in series so the
swamping resistor from screen to ground is a necessity.
73
Gary K4FMX
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Sam's Mail
> Sent: Monday, January 30, 2006 1:12 PM
> To: amps@contesting.com
> Subject: Re: [Amps] cathode to ground in tetrode amp
>
> I have built several grid driven tetrode amps, The cathode is grounded,
> The
> screen does not go to ground through anything. The screen supply should be
> shunt regulated to be able to handle positive and negative screen current.
> Try Ian Whites web site for good information . If you care to build a grid
> driven tetrode I suggest using his tetrode boards. Good luck Sam KF4YOX
> ----- Original Message -----
> From: "Gary Schafer" <garyschafer@comcast.net>
> To: <TexasRF@aol.com>; <Chuck_Partain@maxtor.com>;
> <dezrat1242@ispwest.com>;
> <amps@contesting.com>
> Sent: Monday, January 30, 2006 12:49 PM
> Subject: Re: [Amps] cathode to ground in tetrode amp
>
>
> > >From what I saw it is a conventional grid driven amp. The screen
> resistor
> > >to
> > ground is to prevent negative screen current from raising the screen
> > voltage. The cathode resistor is obviously a mistake.
> >
> > 73
> > Gary K4FMX
> >
> >> -----Original Message-----
> >> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> On
> >> Behalf Of TexasRF@aol.com
> >> Sent: Monday, January 30, 2006 12:10 PM
> >> To: Chuck_Partain@maxtor.com; dezrat1242@ispwest.com;
> amps@contesting.com
> >> Subject: Re: [Amps] cathode to ground in tetrode amp
> >>
> >>
> >> This schematic is a bit hard to read but it looks like the screens of
> the
> >> tubes are grounded. If this is the case, then the cathode has to be
> above
> >> ground
> >> for d.c. by the screen voltage value. RF is another matter and
> >> appropriate
> >> bypass capacitors will take care of that.
> >>
> >> When the cathode is above ground for d.c. rf chokes are needed to help
> >> isolate the rf from the power supplies (all three, grid, screen and
> >> plate). The
> >> cathode bypass C does most of this but an rf choke only helps.
> >>
> >> 73,
> >> Gerald K5GW
> >>
> >>
> >>
> >> In a message dated 1/30/2006 10:14:38 A.M. Central Standard Time,
> >> Chuck_Partain@maxtor.com writes:
> >>
> >> ya
> >>
> >>
> >>
> >> <http://www.angelfire.com/nb/ni4l/gu84b.html>
> >> http://www.angelfire.com/nb/ni4l/gu84b.html
> >>
> >> Look down at the ONE tube schematic.
> >>
> >> This is the only one I have seen for HF so far that's not too
> >> convoluted.
> >>
> >>
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Bill Turner [mailto:dezrat1242@ispwest.com]
> >> Sent: Monday, January 30, 2006 11:11 AM
> >> To: Partain, Chuck; amps@contesting.com
> >> Subject: Re: [Amps] cathode to ground in tetrode amp
> >>
> >>
> >> ORIGINAL MESSAGE:
> >>
> >> At 07:14 AM 1/30/2006, Partain, Chuck wrote:
> >>
> >>
> >>
> >> OK, getting into this more and more every day and learning. Looking at
> >> some
> >> designs on this GU-84b
> >> amp, I see a lot if not most of the cathodes have resistance, some a
> >> lot(30k) some little (.7) to ground.
> >> The screen grid and control grids are not grounded and have
> respectively
> >> ~350 and -150v on them.
> >>
> >> Why wouldn't it just essentially go to ground? what does the R do in
> >> series?
> >>
> >> thanks as always.
> >>
> >> KA1MWP
> >>
> >>
> >>
> >>
> >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>
> >> Is there a schematic we could look at?
> >>
> >> 73, Bill W6WRT
> >>
> >>
> >> _______________________________________________
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> >>
> >>
> >>
> >>
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> >
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