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Re: BX690A/BX695A

Geschreven door John Hupse op 06. Jul 2006 13:11:07:

In reactie op: Re: BX690A/BX695A geschreven door PANDU RAJAN op 06. Jul 2006 10:28:30:

>>>>When the voltage from the output transformer is injected into the cathode of B7 will it also not get injected into the cathode of B4 since both the cathodes are interconnected ?

Hi Pandu,
Yes, in real life things are sometimes more complex. The cathode of B4 is also "injected". To compensate for this the AC signal at the grid of B4 is twice as high as you might expect.
If the G-C signal for B4 has the value U, the injected cathode signal is also U. So the grid signal of B4 has the value U + U = 2U.
The cathode signal of B7 is U, the grid signal of B7 is zero. So the G-C signal for B7 is 0 - U = -U. This trick will simplify the DC bias circuit of the output tubes.

>>>>What is the use of the capacitor C60?
C60 and R47 make a low-pass at 8,83 kHz. This compensates for phase shifts in the output transformer, and will make the circuit more stable and less prone to unwanted oscillations.






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