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Old 23rd May 2004, 05:39 AM   #1
zobsky is offline zobsky  India
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Default 12b4a wiring question

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)?

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


thanks in advance :
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Old 23rd May 2004, 08:37 AM   #2
dhaen is offline dhaen  Europe
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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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Old 23rd May 2004, 08:39 AM   #3
Jax is offline Jax  Sweden
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If you intend to use 6.3V heater voltage, tie 4 and 5 together and feed 6.3V to 3 and the 4-5 joint.

If you use 12.6V, feed 4 and 5, leave 3 floating.

You can use either of the grid pins or tie them together. If you use grid stopper resistor, tie one resistor to each grid pin.
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Old 23rd May 2004, 08:41 AM   #4
dhaen is offline dhaen  Europe
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Default Jax'd.... and stoppered...

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Old 23rd May 2004, 08:58 AM   #5
Jax is offline Jax  Sweden
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We posted in parallel but I took a couple of minutes with the data sheet
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Old 23rd May 2004, 01:18 PM   #6
zobsky is offline zobsky  India
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thanks all,

expect a progress report in a few days, .. touchwood

the tweaking of this thing should be interesting
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