A Stereo guys guide for cleaning the inside of your tubes.

[ALL212]

December is the beginning of Winter and I find myself inside now.  I decided to take some pictures of the tubes I have and found that glass stuff just gets in the way so I've removed a couple of tubes worth for pictures, cleaning and general amusement.  I'm not sure if putting these back together again will be an issue but that's January's task  .

First remove that pesky glass  .  I found that a glass cutter works fine around those tubes that have real bases - a couple of taps and off the glass goes.  For those tubes that are a bit older and the glass a better quality I've used my handy dandy vise.  Wrap the tube in an old t-shirt, crank down the pressure slowly and when it goes "POP" just back it off.  Shake that glass out of the t-shirt and dig out the remains of the tube.  Nothing could be easier!

A very nice 5U4GA/B rectifier.


Not sure what this used to be but here's the disassembly:
With the top mica off...


Outer Shield removed:


Other shieldy (yes - that is a true technical term - just made it up. : ) stuff removed.


Here's another disassembly:

Might have been an expensive tube at one time - nice bottle shaped glass envelope, oh...sorry, that's been removed!


Top Mica removed:


Outer shieldy thing removed:


This one was just cool  8) - no other reason to remove the glass than to see what's inside!  ???  (4EH7)


This one was just weird and had to be examined:  (6BF6)


Anyone here good at glass blowing?  I've saved all the parts but I'm afraid the glass portion didn't make it!

 

[mcandmar]

He he i'm guilty of performing the odd dissection too.  One thing that always surprises me is how tough the grids are, i just assumed they were made of light wire which can easily move causing the microphonic ringing some tubes have, but in reality that are very rigid and difficult to bend. The other surprise was how fragile the heater and cathode coating are.

 

[Doc B]

The outer shieldy things are called plates.

 

[ALL212]

So working from the inside out - heater in the middle - white coated thingy.  Next is cathode then grid, and then anode (plate)?

Took the rectifier apart - no wire - just heater and plate.

 

[mcandmar]

Heater is inside the Cathode (white coated thingy), next is the grid (can be more than one), and then the plate (anode).

Rectifiers are basically the same but dont have a grid, though you can use a triode as a rectifier if you tie the grid to the plate.

Then there are directly heated triodes (DHT) where the heater is the Cathode.

I think that second tube is a beam tetrode, where the inner plate helps direct the electrons to the plate.  There is also two grids inside there, one bring a grid and the other being a screen.  That's about all i know about them.

 

[ALL212]

I believe you are correct, sir!  I have another that looks almost exactly the same - 50L6.

My nephew is a self proclaimed "scrapper" and came across a pile of tubes.  None of which are to be trusted, 1/2 of which are obviously dead (white flashing).  A couple of them look to be very old and I'm keeping them.  One of them a "41", etched base ST shape.  The other is an etched base Philco with the metal cap on an ST shape.

When I went through tech school in the Air Force ~1978ish the B52 old stuff still had tubes.  Instructor told us that if we died handling them he didn't care but if we broke one of them we were in deep Shoot!  If I remember right they were big - 10 - 12 inchers.  I have no clue what they were.