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Old 5th October 2010, 05:58 PM   #1
tofts is offline tofts  United Kingdom
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Default Is this ok

Was taking some HQ long exposures of my RM100.

Noticed a blue glow, I think this is ok, but I thought I would double check.

I know in some cases it could mean they need rebias/replacing

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Click the image to open in full size.
Ultra HQ Version of Above

Thanks,

Jody
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Old 5th October 2010, 06:13 PM   #2
piano3 is offline piano3  United Kingdom
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Is the getter nearly gone?-that is,I think, when I have seen this.
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Old 5th October 2010, 06:13 PM   #3
Mooly is offline Mooly  United Kingdom
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Can you see the blue by eye in the dark ? or just on a long camera exposure.
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Old 5th October 2010, 06:19 PM   #4
athos56 is offline athos56  United States
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I've read that the 6l6s glow like this, AFAIK it is ok.
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Old 5th October 2010, 06:22 PM   #5
tofts is offline tofts  United Kingdom
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Yes, you can see it if its pitch black. But not evident with lights on.
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Old 5th October 2010, 06:28 PM   #6
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Quote:
Originally Posted by tofts View Post
Noticed a blue glow, I think this is ok, but I thought I would double check.
A little blue glow on the inside of the glass envelope is quite normal for output tubes. It's caused by residual outgas from the metal elements being bombarded. Nothing much to be concerned with. A blue haze or glow inside the plate structure would be cause for concern. But this is not the case here.
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Old 5th October 2010, 06:33 PM   #7
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by tofts View Post
Yes, you can see it if its pitch black. But not evident with lights on.
I think it's probably OK too.
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Old 5th October 2010, 06:44 PM   #8
tofts is offline tofts  United Kingdom
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Just another quick query, I have been told that I could use other types of valves when I come to replace these ones. I know the KT66 has the same pins as the 6L6, but what other valves would offer similar specs?

Presumably I could drop them in, rebias and off I go. So long as the replacement valve are similar in specification. I know heater current draw can be vastly different, but judging by the shear size of the power transformer I don't think it should be an issue.
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Old 5th October 2010, 06:52 PM   #9
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by tofts View Post
Was taking some HQ long exposures of my RM100.

Noticed a blue glow, I think this is ok, but I thought I would double check.

I know in some cases it could mean they need rebias/replacing


Thanks,

Jody
Just for interest here is a link!

Wapedia - Wiki: Vacuum tube.

Regards
M. Gregg
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Old 5th October 2010, 06:57 PM   #10
M Gregg is offline M Gregg  United Kingdom
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I think it is O.K.

Is the amp auto bias or fixed bias?
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