Friends I need help, I'm already a few days ago with this amplifier can not find the problem..
The problem is with the D3a tube, not give me enough amplification, with 1V peak-to-peak (1 kHz) at input give me 2.5V to the output.
The anode voltage is 190V (10k resistor load) and the cathode is 2.1 V with a resistance of 104ohms (20mA aprox). Filament 6.6V.
In one tube G2 is connected to the anode and g3 to ground and on the other channel g3 to cathode and g2 to anode, in both channel I have the same result.
The tubes test good in my Eico 667 tube tester (95%)
Any idea?
The problem is with the D3a tube, not give me enough amplification, with 1V peak-to-peak (1 kHz) at input give me 2.5V to the output.
The anode voltage is 190V (10k resistor load) and the cathode is 2.1 V with a resistance of 104ohms (20mA aprox). Filament 6.6V.
In one tube G2 is connected to the anode and g3 to ground and on the other channel g3 to cathode and g2 to anode, in both channel I have the same result.
The tubes test good in my Eico 667 tube tester (95%)
Any idea?


