• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

12b4a wiring question

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another doubt from the trenches

1. the 12ba4 datasheet notes that pin 4,5 are heater pins and pin 3 is the heater center tap. do i omit pin 3 or do i use pin 4,5 as a floating heater circuit and ground to Power supply ground (center tap on high voltage power supply)? :whazzat:

2. pins 2,7 are both grid pins. do i tie them together or just use one of them


thanks in advance :
 
If you have 6.3v available, then link pins 4 & 5, and connect one side of your 6.3v to that, and the other to pin 9.

If you have 12.6v available, connect one side to pin 4 and the other to pin 5. Ignore pin 9.

Use either pin 2 or pin 7, or both to connect to the grid. Sometimes it's convenient to connect the grid leak resistor to one pin, and the signal in, to the other.
 
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