[Amps] cathode to ground in tetrode amp

Gary Schafer garyschafer at comcast.net
Mon Jan 30 17:07:40 EST 2006



> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of gdaught6 at stanford.edu
> Sent: Monday, January 30, 2006 4:19 PM
> To: amps at contesting.com
> Subject: Re: [Amps] cathode to ground in tetrode amp
> 
> On 30 Jan 2006 at 13:12, Sam's Mail wrote:
> 
> > 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 .
> 
> You'll notice that Ian still recommends a shunt resistor to ground.
> 
> > If you care to build a grid driven tetrode I suggest
> > using his tetrode boards.
> 
> That's very good advice, in my opinion!
> 
> > ----- From: "Gary Schafer" <garyschafer at comcast.net> To:
> >
> > > >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.
> 
> IMHO, the cathode resistor is not "obviously a mistake."  Rich
> Measures' website (and I) often recommend some cathode degeneration,
> aka negative feedback, primarily to help linearity.
> 
> 73,
> 
> George T. Daughters, K6GT
> 

30K of cathode resistance for negative feed back Seams a little high. :>)

73
Gary  K4FMX






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