[mordy]

Did my Google search (could not find anything similar looking on eBay now). - I does look similar to RCA, but the top mica does not look the same so not sure - it could be something else.
( Found a seller that has the RCA for $15 but the picture is not identical ):
https://lowtechelec.com/products/rca-6j5-6j5g-vacuum-tube-valve-st-shoulder-shape-nos-testing

 

[Xcalibur255]

If I can ask the collective brain trust here about internal constructions (specifically by way of the top mica support. Who do you think made this (6J5G) tube? I've only got one answer so far from a tube collector whom I generally trust - but want to see if it aligns to what you all think. Thanks!

I was wondering about this one too. The top mica spacer design and mica shape say National Union to me actually. You can see it in other NU tubes from the 30's such as their 45 tube.

That's my first guess FWIW.

 

[therremans]

If I can ask the collective brain trust here about internal constructions (specifically by way of the top mica support. Who do you think made this (6J5G) tube? I've only got one answer so far from a tube collector whom I generally trust - but want to see if it aligns to what you all think. Thanks!

This Silvertone I own matches up. “6 C X” However it’s an oddity, as it’s a 6C5G without the cage or is actually a 6J5G? I typically think of National Union making most of the Silvertone tubes. Not sure who made these. Maybe it is RCA or Ken Rad?

 

[Slade01]

I was wondering about this one too. The top mica spacer design and mica shape say National Union to me actually. You can see it in other NU tubes from the 30's such as their 45 tube.

That's my first guess FWIW.

I would consider your guess to be 98-100% correct - you kind of help validate this for me. I was told from an avid tube collector that this tube was manufactured by Arcturus. I'm not sure how the history connects but I know that Arcturus/National Union are often mentioned in the same scope. This tube is from 1939 - I bring it up also because @Xcalibur255 it is also a GM Branded tube. Looking up Arcturus, up until perhaps the 2nd world war, they were making their own tubes - shifting to rebranding after the war.

@therremans - yes I agree with you and Xcalibur255 about it being probably National Union (Arcturus?). My tube also bears the similar round logo proclaiming it to be a 6J5G (instead of the stop sign insignia). The top mica is a dead ringer to your 6C5G Silvertone - (and without a cage - that is kind of cool too, definitely an oddity--unique.)

He was the only one who seemed to definitively know, but have never gotten any real confirmation from any one else to reaffirm the internal construction. Thank you all for taking the time to look...I appreciate your help.

For kicks - this is the original box for the GM Branded Tube.

 

[maxpudding]

It is always nice to see pieces of history here

 

[Xcalibur255]

Silvertone was an in-house brand for Radioshack if memory serves. I have noticed that it's quite common for the Silvertone tubes to be made by National Union, but it's not exclusively the case.

Arcturus is a wild card, and I don't know much about them. Some of the biggest unicorns in the tube world (mesh plate blue glass stuff) are Arcturus, along with Taylor, Cunningham and other brands that all vanished after WWII or in the lead up to it. Speaking purely in terms of name coolness I have to say I'm a fan of Arcturus. It's not Super Air Castle cool, but it's still cool.

edit: Memory does NOT serve it turns out, it was Sears Roebuck and Co. not Radioshack.

 

[Xcalibur255]

My tube also bears the similar round logo proclaiming it to be a 6J5G (instead of the stop sign insignia).

The on glass logo can help with ID sometimes, but in my experience not that much. It seems like a circular logo was the standard in the beginning and manufacturers gradually moved to the stop sign logo over time, but they all did it at different points in time. National Union basically kept using the circle for as long as they made tubes. Very old Sylvania tubes from the 20's and 30's are circle logo, but once you hit WWII they switch to octagon. Same with Tung-Sol only I think the transition happens a bit earlier with them in the late 30's. RCA, on the other hand I think might have come out of the gate using the octagon. There are really old tubes that have circle logos but these were actually made by Cunningham for RCA in the late 20's and early 30's. The only brand that continued to use a circle logo into the 50's was CBS/Hytron I think. Philco had both because the generally tended to be re-brands so they'd pick up the style of the real manufacturer. I think Ken-Rad changed when GE took ownership of them so only their early tubes were circle logo.

That's just what I recall off the top of my head based on what I've seen over the years.

 

[Slade01]

Arcturus is a wild card, and I don't know much about them. Some of the biggest unicorns in the tube world (mesh plate blue glass stuff) are Arcturus, along with Taylor, Cunningham and other brands that all vanished after WWII or in the lead up to it. Speaking purely in terms of name coolness I have to say I'm a fan of Arcturus. It's not Super Air Castle cool, but it's still cool.

Yeah - ever since I saw @gibosi 's logo of the blue type 126 as pictured on his profile pic i've been interested in the Arcturus Brand. Yeah - not as cool sounding as Super Air Castle...but the original Arcturus logo and box branding design is really cool to me.

The on glass logo can help with ID sometimes, but in my experience not that much. It seems like a circular logo was the standard in the beginning and manufacturers gradually moved to the stop sign logo over time, but they all did it at different points in time. National Union basically kept using the circle for as long as they made tubes. Very old Sylvania tubes from the 20's and 30's are circle logo, but once you hit WWII they switch to octagon. Same with Tung-Sol only I think the transition happens a bit earlier with them in the late 30's. RCA, on the other hand I think might have come out of the gate using the octagon. There are really old tubes that have circle logos but these were actually made by Cunningham for RCA in the late 20's and early 30's. The only brand that continued to use a circle logo into the 50's was CBS/Hytron I think. Philco had both because the generally tended to be re-brands so they'd pick up the style of the real manufacturer. I think Ken-Rad changed when GE took ownership of them so only their early tubes were circle logo.

That's just what I recall off the top of my head based on what I've seen over the years.

Yeah - I figured that the circular logo was more or less used in the beginning and over time changed over to the octagon design. Interesting to know that NU always used it for the entire time they were around. I also know that WW2 also really scrambled the whole tube ecosystem for demand-manufacturing/rebranding.

Arcturus definitely had cool branding. Then wonder if the tube pictured on the right below is a rebrand or not. Though the left one also - the font and lettering is similar to other metal tubes i have so who knows. Forever a mystery I suppose but i guess that is par for the course for a unicorn company.

 

[mordy]

I am sure that the tubes in those light blue boxes aren't original Arcturus tubes but rebrands.
The original Arcturus boxes were very pretty:

Here is a good reference about the Arcturus history:

https://www.antiqueradios.com/forums/viewtopic.php?t=152508
Arcturus was established in the 20's and made tubes with blue glass as a gimmick. The company went bankrupt in the early 40's. Afterwards the brand continued under different ownership as a distributor up til 1952 when the owner died. In 1959 people bought the right to the Arcturus name and sold rebranded tubes under that name. Most likely the light blue box pictured above is from the post 1959 era.

 

[mordy]

Also want to add that many times there are letters/numbers/symbols engraved on the ring at the base of the metal tube. Sometimes this, as well as the exact shape of the metal envelope, can give you a clue to the manufacturer, but admittedly it is difficult to confirm when you cannot see the internal construction.
I have a Tung Sol 12SN7 BGRP rebranded as Arcturus as well as a couple genuine Arcturus 6N7G tubes - the internal construction is unique.

 

[Slade01]

I am sure that the tubes in those light blue boxes aren't original Arcturus tubes but rebrands.
The original Arcturus boxes were very pretty:

Here is a good reference about the Arcturus history: https://www.antiqueradios.com/forums/viewtopic.php?t=152508
Arcturus was established in the 20's and made tubes with blue glass as a gimmick. The company went bankrupt in the early 40's. Afterwards the brand continued under different ownership as a distributor up til 1952 when the owner died. In 1959 people bought the right to the Arcturus name and sold rebranded tubes under that name. Most likely the light blue box pictured above is from the post 1959 era.

Yeah - love the original box design (observatory). I just actually now noticed in my picture.....on the plain Arcturus tube I have on the right pictured, the octagon symbol has breaks and a big fat dot at the top/edge. I remember this being an RCA trademark to signify date code? Maybe its an RCA?

 

[whirlwind]

I have these Arcturus 6J5G tubes...originally thought they may be Sylvania's....not so sure now.

 

[therremans]

I have these Arcturus 6J5G tubes...originally thought they may be Sylvania's....not so sure now.

I think RCA or NU. Sylvania is of a different construction.

 

[mordy]

I think RCA or NU. Sylvania is of a different construction.

Are there any codes on the tubes? Not that it will help lol because I don't think that there is any information on the Arcturus coding, but there is the possibility that these tubes are made by Arcturus and not rebranded.
My guess is that if they were made before the early to mid 40's they could have been made by Arcturus.

Just checked several different listings on eBay old and current and can't find anything that looks like the Arcturus.

 

[whirlwind]

Are there any codes on the tubes? Not that it will help lol because I don't think that there is any information on the Arcturus coding, but there is the possibility that these tubes are made by Arcturus and not rebranded.
My guess is that if they were made before the early to mid 40's they could have been made by Arcturus.

Just checked several different listings on eBay old and current and can't find anything that looks like the Arcturus.

S
A

This is all that is on the tubes other than the Arcturus name and I am not even positive the top letter is S for sure as it is a bit worn.