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

http://www.dragonsbloodtribe.co.uk/i.../valve1024.jpg
Ultra HQ Version of Above

http://www.dragonsbloodtribe.co.uk/i...valves1024.jpg
Ultra HQ Version of Above

Thanks,

Jody

Is the getter nearly gone?-that is,I think, when I have seen this.

Can you see the blue by eye in the dark ? or just on a long camera exposure.

I've read that the 6l6s glow like this, AFAIK it is ok.

Yes, you can see it if its pitch black. But not evident with lights on.

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.

I think it's probably OK too.

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.

Just for interest here is a link!:)

Wapedia - Wiki: Vacuum tube.

Regards
M. Gregg

I think it is O.K.

Is the amp auto bias or fixed bias?