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Re: 6bq5 triode configuration? (Longer)

Posted by Damir on March 9, 2002 at 13:35:34

In Reply to: Re: 6bq5 triode configuration? (Longer) posted by chopper87 on March 9, 2002 at 12:19:34:

If I understood you correctly, you have a PP pentode amp with two pairs of EL84s. All g2s (pin 9) are tied together and connected to common screen grid supply with 350 Ohms resistor and jumper wire (unusually) to can condenser. Disconect this jumper wire and resistor, and there`s nothing connected to strings of pins 9, right? Disconect all jumpers from pin 9s from tube to tube. Now, you have nothing connected on g2s (pin 9s) of the neither of EL84s.
You forgot to mention, but you have the anodes (pin 7) of the tubes 1 & 2 tied together with jumper wire, and it goes to one end of the primary. Similarily, the anodes of the tubes 3 & 4 are also tied together and connected on the other end of the primary. As I said B+ is connected to the center tap.
Now, connect resistor of say, 150 Ohms/1W between pins 7 & 9 of the first tube. The same goes for second, third and fourth tube - solder 150 Ohms resistor between a and g2.
Of course, you can leave jumpers between g2s of the tubes 1 & 2 and 3 & 4, and use only one resistor between connected anodes and connected screen grids of the tubes 1 & 2, and the same for tubes 3 & 4, but I think that an individual resistor for each tube is a better solution.
Good luck!

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