Posted by redsetter (A) on June 27, 2003 at 08:40:46

In Reply to: Re: Choking that filament supply! posted by twystd on June 26, 2003 at 11:22:44:

Yup,

Can confirm that the shottky's, choke and good caps are a good thing.

Also you will want to try bypassing each of the schottkys with a .1mf good quality cap and the other thing I have tried is to balance the centre tap of the HT.

There are two red colored wires coming from the power transformer to the rectifier tube and a red/yellow that is attached to the ground bus. If you measure the resistance from each of the red wires to the ground bus they should be the same (but they are not becuase one wire is slightly longer than the other - they are wound over each other) - this caused a ripple to get into the supply that cannot easily be filter out. The way to cure this is to add an equalisation resistor to one leg. In my case I measured 54 ohm on one leg and 54 ohm on another - so I added 3 ohms to one leg.

Try it!

Red....

• Re: Choking that filament supply! - twystd 10:35:11 06/27/03 (4)
  In Reply to: Re: Choking that filament supply! posted by redsetter on June 27, 2003 at 08:40:46:

  Thanks Red, I'll try the balanced HT center tap thing. Not quite sure how to implament the caps bypass on the schottkys, as I have a Schottky bridge, and I'm I'm not sure how to wire it up. It should take 4 caps for the bypass correct?

  twystd
  
  

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  • No real need to cap the schottky as they have "no" switching noise <nt> - Chris O 17:31:29 06/29/03 (1)
    In Reply to: Re: Choking that filament supply! posted by twystd on June 27, 2003 at 10:35:11:

    
    
    

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    • Re: No real need to cap the schottky as they have "no" switching noise <nt> - redsetter 02:20:14 06/30/03 (0)
      In Reply to: No real need to cap the schottky as they have "no" switching noise posted by Chris O on June 29, 2003 at 17:31:29:

      Conceptually I agree with you Chris.

      I am no expert - but reading Morgan Jones (where I get some of these tips from) he clearly beives that there is benefit in doing this.

      If want to try this with a bridge then do a bypass as follows:
      -ve to both ~ (two bypasses)
      +ve to both ~ (two bypasses)

      Red...
      
      

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  • Where did you find the Schottky Bridges?(nt) - Ron W 13:55:25 06/27/03 (1)
    In Reply to: Re: Choking that filament supply! posted by twystd on June 27, 2003 at 10:35:11:

    .
    
    

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    • Re: Where did you find the Schottky Bridges?(nt) - twystd 16:50:43 06/27/03 (0)
      In Reply to: Where did you find the Schottky Bridges?(nt) posted by Ron W on June 27, 2003 at 13:55:25:

      Hi Ron

      Got them at VSAC 2001, got a great price, so bought 10. A very friendly dude sold them to me, can't remember his name. He got them from Japan. If memory serves, he was a friend of Gary Prim, Gary might be able to get you more info.

      twystd
      
      

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