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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Re: Grid choke and optimum coupling cap value posted by Deco-Doctor on July 2, 2006 at 04:42:06:
Hi,> Would I be correct in saying that as the coupling cap and
> the choke form a series resonant tank circuit there would
> be attenuation (pass filter) of the signal at and around
> the resonant frequency?You would be wrong, of course we have a parallel resonance circuit, where the source impedance of driver stage in series with coupling capacitor froms one element and the choke the other. So the result is a severe peaking of the FR (6 - 20db!!!!).
> I think I will increase the cap value to .32uf by adding a 0.1uf
> russian teflon cap across the .22 pio I have in there.That will do not much to alleviate the (potential) problem. In order to push resonance down to 4Hz you need 2.2uF....
> I also have another pair of 640H chokes on the way to me, so I
> may try adding another in series to give me 1280H. I think I
> would be correct in saying that this would be better than
> making the cap biggerYes, you are right on that account.
> Also what would be a suitable damping resistor to put across the
> choke? 1M ohm?Try 100K or less to get a resonable impact.
Ciao T
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- Re: Grid choke and optimum coupling cap value - Thorsten 07:55:24 07/02/06 (0)
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