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Old 2nd February 2005, 02:52 AM   #1
zxx123 is offline zxx123  United States
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Default 6V6 SE and Screen Grid Voltage

Hi, everybody~

I tried UL tap, which is around 300V driven.
However, in application data, I found that V on screen grid
should be 225V.

Am I doing wrong? Neither hum nor distortion (liitle bit in high
frequency in loud volume.) exists.

Thank you.
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Old 2nd February 2005, 05:58 AM   #2
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Well, lets see here

The data sheet says that the max value is 285V on g2.

What transformer are you using? Do you know what % the UL tap is? Most are 40%, but that is not always the case. 43% is for min distortion and 20% is for max power. so it really could be anyware inbetween.

The 225V that I think you are refering to is for a straight Class A1. U/L is different. Meaning that g2 would be getting its 225V from its own power supply tap, and not from an U/L tap on the OPT. I didn't see any specs listed for class A U/L.

So let us know what transformer you have, and if you are going for straight class A or for class A U/L. They are two different animals.

Hope this helps

Matt
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Old 2nd February 2005, 03:40 PM   #3
zxx123 is offline zxx123  United States
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thanks
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Old 2nd February 2005, 04:56 PM   #4
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You might be okay with the 300 on g2. But it may shorten tube life a bit. If it was me, and the U/L wasn't working out. I would set up a power supply tap to give the 225V that the data sheet indicated. For even better performance I would regulate that 225V. But only in pure pentode mode. U/L mode relies on g2 being in sync with the plate.

Matt
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Old 2nd February 2005, 05:11 PM   #5
zxx123 is offline zxx123  United States
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Default Full Schematic of 6V6SE

Here it is.

6v6 is very cheap...
i may replace them once a year.
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Old 2nd February 2005, 05:36 PM   #6
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okay, heare is my next concern. Although there designs out there that put g2 at a higher potential than the plate. they are not very common. What will happen is the the screen will start to dissipate alot of power. I think the data sheet said that the 6v6 could dissapate 2W on the screen. You have to be certain that it does not exceed that rating. I would get nervous if it started to get close to that.

With that being said I have an amp with 7027's that I have only 10V less on the screen than on the plate. But I am running those tubes very, very hard. So with the 530+ on the plate, and something like 525 on the screen, it works. but the whole tube is running right at its breaking point. But does it sound sweet. Again, that tube can dissapate 5W on g2 (and I am below that point, but not much below). But I am exceeding the 500V rating for it (g2).

So can you get away with it...yes. Just be careful or you could melt the screen.
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