Not the normal "blue glow" question

[Johntb]

So I am in building/designing a single ended triple parallel amp. No preamp on it yet. Using an EC832 to drive it. There is a separate volume for each octal tube.
 I have used the following successful combinations:
6V6 6V6 6V6 / 6V6 6L6 KT88 (my favorite) / EL34 6L6 KT88 /6L6 6L6 KT88 and other combo's of these tubes I have 3 6V6, 2 6L6, 1 EL34, 1 KT88.

The 6L6's and KT88 glow blue 6L6 has more blue.

So using my homemade current limiter with 250watt light bulb. The 6L6's cause the limiter to just barely glow. The EL34 makes it glow a little brighter.

Are these tubes bad?

Side note they sound ok to me even when I don't plug into the limiter and does not blow a fuse.

[shooter]

The 6L6's and KT88 glow blue 6L6 has more blue.

If it's "contained" inside the plate, it's probably ok.  If it's outside the plate area it's probably gassy, n on it's last leg from my understanding.
you can google gassey tubes and find some examples, I have a gold lion 6550 that is way gassy, rays coming out of the holes, an aura around the outside of the plate, I use it only as at temp tube to get current and voltage measurement before I use a known good

what are you running for plate and current?  do each tube get its own cathode R&C?

[Johntb]

The 6L6's and KT88 glow blue 6L6 has more blue.

If it's "contained" inside the plate, it's probably ok.  If it's outside the plate area it's probably gassy, n on it's last leg from my understanding.
you can google gassey tubes and find some examples, I have a gold lion 6550 that is way gassy, rays coming out of the holes, an aura around the outside of the plate, I use it only as at temp tube to get current and voltage measurement before I use a known good

what are you running for plate and current?  do each tube get its own cathode R&C?

The KT88 is inside the plate. The 6L6's and EL34 pretty sure are gassy. They are all around the glass. Each has it's own cathode R&C. Plate is 283v not sure current don't trust my meter getting weird readings from 23-123 and everything in between. I know volts are good though.

[shooter]

not sure current don't trust my meter

try new batteries, but you can calc I from the voltage at the cathode / by the R.  You only really get proper reading at idle - no signal, otherwise everything becomes dynamic.

mark the gassey and use for testing, or play it till they toast

[Tony Bones]

How is this not the "normal blue glow question"?

Deep blue around the inside surface of the glass is OK. It's the glass itself fluorescing from electron bombardment. Any color glow anywhere else inside the tube indicated the presence of gas (i.e. compromised vacuum.)

https://www.google.com/search?q=tube+blue+glow&ie=utf-8&oe=utf-8

[Johntb]

How is this not the "normal blue glow question"?

Every "blue glow" question I have seen is: is my tube bad?

My question is why is my current limiter lighting up with only a couple tubes that glow blue but not all? So it's not so much about the blue glow itself but partially how much of a blue glow is ok?

I understand that the blue glow is "normal" depending who you ask but my KT88 has a faint blue glow  and is fine. The 6L6's glue throughout the tube and when in the socket the current limiter starts to light up.

[Johntb]

not sure current don't trust my meter

try new batteries,

mark the gassey and use for testing, or play it till they toast

These are new batteries. I stopped using this meter at work when it showed and open 60uf@440vac on a rooftop A/C unit I was troubleshooting..... ....... It wasn't open.

I was planning on using the 6L6 until it dies as a bench tester.

[PRR]

Lamp-limiter is brighter on EL34 because the '34 sucks more heater current. (You got like 5 Amps in that trio!)

Amp this big, the lamp should be well over 100W Incandescent. Big enough to not hot-up with this amp's large normal current, yet not so many Watts you endanger your house-wires.

Blue Glow stuck on the inside of the glass is glass impurities fluorescing with stray electrons. Varies with the glass used. Tube makers don't reject glow-glass, it is a semi-common impurity which does no harm. It depends on the lot of glass they got that week, so does not go by Type or Brand of Date.

[Johntb]

Lamp-limiter is brighter on EL34 because the '34 sucks more heater current. (You got like 5 Amps in that trio!)

Amp this big, the lamp should be well over 100W Incandescent. Big enough to not hot-up with this amp's large normal current, yet not so many Watts you endanger your house-wires.

Blue Glow stuck on the inside of the glass is glass impurities fluorescing with stray electrons. Varies with the glass used. Tube makers don't reject glow-glass, it is a semi-common impurity which does no harm. It depends on the lot of glass they got that week, so does not go by Type or Brand of Date.

Thank you!!!

This pretty much explains everything I was asking. The limiter is lighting because of the heater current (more than I was expecting).

I found a 250 watt bulb at Lowes when I made it.

Thank you again.