[Amps] cathode to ground in tetrode amp

TexasRF@aol.com TexasRF at aol.com
Mon Jan 30 12:09:58 EST 2006


 
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 at 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 at ispwest.com]
Sent: Monday, January 30, 2006  11:11 AM
To: Partain, Chuck; amps at 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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