I recieved this along with the 63303C, I had to buy new tubes as 2 of the orig tubes were missing when I recieved it. These were generally used to control strings of lights at one time. Another cool feature on these is the ability to adjust the foot candles for the amount of light required to operate. This was done buy adjusting a nut on the backside ot the PC.
The tubes I used are the same as what were in the other model. I bought a couple NOS RCA and the tube on the left is a 6SJ7 and the right is a 6SQ7. The photo tube was still installed.
Thanks for that link, Thats cool to see some info on these tubes! I did double check and it is 6SQ7 on the right! Odd there is no info seeing as they are so close in #.
Ok so what you mean is they mfg the tube and when they test it depending on the results is what they mark them as? I know very little as far as tubes go! Though I have a ton of them I removed from an old TV cause I thought they looked cool!
Vacuum tubes are made on a production line, like any incandescent or flourescent lamp. During final test they are tested to conform to spec, and if there is a demand for a certain range of characteristics, like mu (gain) or for low noise or a defined gain in a certain circuit then they will be evaluated, and those that are in the range will be specially marked. Sometimes the difference can be in pinout, or in a special package option ( a metal shield for low noise, or a high temperature range version). Rather like transistors, where you can buy a unit that is somewhere in a broad range of parameters, or a more expensive unit that is selected to be in a narrower range. It may have a different part number, or a suffix to denote this
Thats cool info! Thanks! So that can explain as to why you can have 2 tubes that look identical but may have different markings. I used to work at a bowling alley and the old foul light system used tubes! Yes it was an old bowling alley! All that equipment has since been upgraded so I got the old tubes. They are all 6SN7 tubes!
Yes, you could have a production spread of 20% or more, but bin that into 3 ranges that are much more tightly controlled, and make the parts virtually interchangeable for servicing, as they have a limited lifetime, mostly due to either losing emission from the cathode, or from ion damage to the thin electrodes, or from gas diffusion into the unit.
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