Need help to ID this Tube

[k5ygc]

Rectifier but what number?  Mark K5YGC

[W8ACR]

How many pins at the base? and can you show a pic looking down from the top?
My guess at this time is either an 80 or an 83.

[k5ygc]

Eight pin I have a 83 here looks nothing like it. I have search the web no luck finding one with the piece around the bottom o the plates. Pic of top attached.

[W8ACR]

Does the octal base have all eight pins present? Most common rectifiers only have five pins on the octal base. I don't recall seeing an internal structure like the one shown, but it may just be a variant of a common number.

[W8KHZ]

One trick I learned on tubes with the markings rubbed off... shine a really bright LED flashlight on the glass envelope. Often markings that are not visible in the ambient light are readily visible under the intense light of the LEDs.  Give it a try you might get lucky!

Brian  W8KHZ

[KB2WIG]

Breath deeply, exhale on envelope....it works.  Sometimes.

If you have a UV lamp, try illuminating the tube with the UV lamp.

good luck.

klc

[W3NE]

klc's reply above is an ancient but effective method to reveal faint tube types and date codes. Open your mouth wide and slowly exhale all over the envelope surface. Moisture in your breath will condense slightly differently where the old ink still remains, possibly making the type visible under the proper light.

Another oldie is to pass the tube lightly through your hair (if any). Natural oil in the hair might make the tube type stand out.

An excellent source of information about tubes is The Tube Collectors Association www.tubecollectors.org/ where Lud Sibley, WB2EVN might be able to identify your tube from the photos.

Bob - NE

[WA4WAX]

Put the tube in the freezer fro about 10 minutes, then bring it out.

With luck, you will be able to read the latent stencil.


Matt

[WA2IXP]

Mark,
   Looks like its on a power supply chassis. As someone mentioned earlier octal rectifiers have unused pins missing to raise breakdown voltage between pins I think.  could it be a 6AS7 triode used as a shunt or series regulator. They actually had 2 triodes in parallel in the same envelope.  Another similar one was a 6080 but more modern in appearance. low mu very low plate resistance . If I recall one could see the grid structure between the plates and cathodes thru the glass. 

[k5ygc]

Mystery solved turns out to be a 6AS7 exhaling on the tube worked. It is used on a power supply built on a rack mount Seeburg chassis and a huge Seeburg volt meter. A pair of OD3'S and 6sh7 and a 5U4 I googled the Seeburg model # and no luck finding any info on it. Thanks for all the help K5YGC Mark