Re: CCS Guidance

K&K Audio / Lundahl Transformers

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In Reply to: CCS Guidance posted by RC Daniel on September 9, 2004 at 21:26:50:

Konnchiwa,
> To design the driver stage to accommodate the CCS:
> 1. Select approximate driver operating points per normal and derive
> the cathode R and required plate V (as per normal).
Yup.
> 2. Add approx 20% to the required plate V to allow enough B+ V for
> current source operation.
No, ABSOLUTELY WRONG. The +B must be the full desired output swing plus around 10 - 20V for the dropout voltage of the CCS ON TOP of the Anode voltage.
So, if where to operate a russian 6S45PE at 180V/10mA to drive a 300B with 71V bias we want AT LEAST 71V swing plus 15V Dropout voltage plus 180V anode voltage, or 266V.
> 3. The CCS replaces what would normally be the plate R; the cathode
> bypass C can be eliminated; the cathode R stays per normal.
I would not recommend removing the Cathode bypass capacitor, the key reason being that doing so raises the output impedance of the stage drastically.
In my example, the 6S45 Stage with a bypassed cathode resistor of around 250 Ohm for biasing would have around 2K output impedance. Remove the bypass capacitor and the output impedance rises to nearly 15K!!!
> When testing, adjust the variable R on the CCS to get the correct
> plate V for the stage.
That is one way. It may not work too well if your valves vary much in biasing. I would adjust the CCS out of circuit with a 9V Battery or thereabouts for the correct current and then adjust the cathode resistor for the correct Anode voltage.
Sayonara

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Follow Ups Full Thread

Topic - CCS Guidance - RC Daniel 21:26:50 09/09/04 (6)

Re: CCS Guidance - RC Daniel 15:37:38 09/10/04 (2)

Re: CCS Guidance - KevinC 06:50:55 09/11/04 (1)

Re: CCS Guidance - RC Daniel 15:31:02 09/11/04 (0)

Re: CCS Guidance - Kuei Yang Wang - The real one 06:14:56 09/10/04 (1)

Re: CCS Guidance - KevinC 08:01:08 09/10/04 (0)

Re: CCS Guidance - KevinC 05:05:49 09/10/04 (0)

Follow Ups

Re: CCS Guidance - Kuei Yang Wang - The real one 06:14:56 09/10/04 (1)

Re: CCS Guidance - KevinC 08:01:08 09/10/04 (0)

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