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Old 25th March 2014, 11:03 AM   #1
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Default Grid 2 current for GU19-1

Hi,

I am currently building a PP with GU19-1 tubes but I cannot find informations nor curves about their g2 current. Do some of you have informations about that ?

Cheers,
Greg
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Old 26th March 2014, 09:27 AM   #2
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From this link I can understand the following specifications (mixed with some others from the DS):

With anode 350V @ 40mA & grid2 250V:

Heater current: 6.3V (2A+/-0.2) 12.6V (1A +/- 0.1)
Grid 1 voltage: -17V
Grid 1 current: 10µA
Grid 2 current: 8mA
Grid 2 max power: 6W

Cheers,
Grégoire
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Old 26th March 2014, 10:14 AM   #3
Tesla88 is offline Tesla88  Italy
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Can be helpfull?
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Old 26th March 2014, 01:13 PM   #4
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Thanks Tesla but I have already that one and it shows no informations about g2 current.

The reason I want to know about that is I want to build a current limiting voltage regulation for this grid, so I need to know about its maximum current ratings.

With 6W max dissipation, at 250V it means 30mA max for each tube. I wanted to know if Ig2 could go above this limit in normal use case.

Cheers,
Greg
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Old 26th March 2014, 03:23 PM   #5
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From Datasheet {grid2 current not above 26mA}
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Old 26th March 2014, 04:23 PM   #6
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Quote:
Originally Posted by chanmix51 View Post
... I want to build a current limiting voltage regulation for this grid, so I need to know about its maximum current ratings.

With 6W max dissipation, at 250V it means 30mA max for each tube. I wanted to know if Ig2 could go above this limit in normal use case.

Cheers,
Greg
Remember that this is the average current. Peak current during positive drive cycle is much higher.
You regulator "system" must be able to handle this.
If it limits the peak current to 30 mA, you will get only little power out of that tube.

I have never seen necessary to build current regulating screen supply.
Voltage regulator and some series resistance would be good for most demanding purpose I have had.
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Old 26th March 2014, 04:38 PM   #7
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Thank you Tesla

Writing this post made the problem clear to my mind, I had the answer since the begining

Cheers,
Greg
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Old 27th March 2014, 11:38 AM   #8
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Quote:
Originally Posted by artosalo View Post
Remember that this is the average current. Peak current during positive drive cycle is much higher.
You regulator "system" must be able to handle this.
If it limits the peak current to 30 mA, you will get only little power out of that tube.

I have never seen necessary to build current regulating screen supply.
Voltage regulator and some series resistance would be good for most demanding purpose I have had.
Sorry Artosalo, we did cross posts and I didn't see your answer.

You are right, the 26mA g2 current is the condition for 40W output power @ 500MHz class B. The idea behind current limitation was to protect grids 2 in case of a loss of connection in the anode circuit (anode caps).

Without more informations about g2, your solution is probably the best.

Cheers,
Greg
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Old 27th March 2014, 03:32 PM   #9
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Quote:
Originally Posted by chanmix51 View Post
...The idea behind current limitation was to protect grids 2 in case of a loss of connection in the anode circuit (anode caps)...

Cheers,
Greg
A 100 mA...200 mA fuse would be good for protecting G2 in such case.
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