Is this normal?

2nd harmonics for the masses

Is this normal?

Postby ica2000 » Tue Sep 17, 2013 7:36 am

Hi All,

built my first get*set*go and everything is fine according to the sound. (Quite fine) BUT I noticed a blue to ultraviolet glow coming off the 300b's. 300b mods are straight off the thread from the splash page including remaking a diode octal plug for the rectifier. The photo was taken in darkness over 60 seconds. Its hard to see in this photo but the heater elements do peek out more on the tube on the left with the larger amount of blue light.
Image


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Re: Is this normal?

Postby TerrySmith » Tue Sep 17, 2013 8:01 am

Yep, perfectly normal. I've noticed the blue glow on Sovtek / Electro Harmonix 6B4G's also. It usually fades away over time.

Nice lookin' amp also!
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Re: Is this normal?

Postby johnf » Fri Sep 20, 2013 10:56 am

The NOS Russian 6C4C tubes also have this blue glow
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Re: Is this normal?

Postby EWBrown » Fri Sep 20, 2013 8:21 pm

The blue glow, if it appears on the inner surface of the glass envelope is normal and OK, if it appears inside the plate, then that indicates a gassy tube.
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Re: Is this normal?

Postby ica2000 » Fri Sep 20, 2013 10:46 pm

Thanks,

Always pays to double check. The blue glow is "on" the envelope so that is good. Now that I know what it is my inner OCD adult is bugged that the glow isn't equal in both tubes.....
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Re: Is this normal?

Postby EWBrown » Mon Sep 23, 2013 8:40 am

This phenomenon is common with power triodes and Beam Power Tubes. Sometimes the blue glow will pulsate in time with the music being played.

/ed B
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Re: Is this normal?

Postby johnf » Sat Sep 28, 2013 9:29 am

My tubes don't glow evenly either. They also pulsate in time to the music .
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Re: Is this normal?

Postby Geek » Sat Sep 28, 2013 4:34 pm

If music plays and no smoke is billowing out, call it a day and enjoy [:)
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Re: Is this normal?

Postby jwhitmor » Sat Jan 25, 2020 3:27 pm

Wow, I love it. Where can I get some of those glowing tubes? (love)
If it is not making X-rays, your B+ is too low.
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