From: none@ntlworld.com   
      
   On 12/10/2010 21:37, Richard wrote:   
      
   I said   
      
   > I'v wired the KT88 triode connection. Anode and screen are at same   
   > potential because they are connected.   
      
   > There is a 270R cathode bias resistor, which serves to effectively place   
   > a bias on g1, because g1 connects to "earthy" end of the bias resistor.   
   >   
   > Okay, with this setup (which may be deficient, but I would not know why)   
   > anode current goes way up to 240mA, the voltage output from PSU drops to   
   > about 250V. Under these conditions bias resistor develops 64.8V.   
      
      
   Okay, I made a change which altered the readings significantly.   
      
   I have a triode connection, ferrite beads on anode, screen and grid   
   wires, but I had only a 1K0 grid stopper next to g1 pin on the tube   
   socket. A 270R cathode bias resistor.   
      
   Ia was 240mA   
   Voltage across bias resistor was 64.8V   
   PSU voltage 250V (dropped 60V due to overdrawing PSU design current)   
      
   I took out the grid stopper, and simply placed ferrite beads on the grid   
   wire.   
      
   Now the figures are:   
      
   Ia 90mA   
   Voltage across bias resistor is 24.3V   
   PSU Voltage is 310V   
      
   Removing that 1K0 grid stopper altered the whole thing. Things look much   
   better.   
      
   Why did removing the 1K0 resistor in g1 circuit change things so   
   significantly?   
      
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