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In Reply to: Re: Sand posted by Henry Pasternack on December 15, 2006 at 06:18:26:
Dear Henry,Thank you very much for your considerations. Two remarks:
In my orginal post I asked for a solution to create a low DC resistance path from grid to ground while using fixed bias trough a grid choke (or secondary of a driver transformer).
Whatever the PSU, without proper measures the PSU will be between ground and grid, therefore adding to the grid to ground resistance. My analysis was that a high DC resistance to ground would defeat much of the benefits of a grid choke. As I see it, only a potmeter with one leg grounded will provide a alternative low resistance DC path to ground, adding only the series resistance of the pot.
Further. I tried to simulate a choke input bias supply, but since now current flows, I see no benefit in choke input. The first choke does needs to be HUGE to the lack of current. My idea was to use a CRCLC supply, followed by a voltage divider (pot), common mode choke and a paralel cap to lower output Z. According to PSUD this gives less than 0.5mV ripple. So why the choke input?
Like everybody, I'm learning so I might overlook some things.
Regards,
NC
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