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Are these "United National" tubes made by EI?
Are these "United National" tubes made by EI?
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Old 7th March 2018, 07:45 AM   #1
nzoomed is offline nzoomed  New Zealand
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Default Are these "United National" tubes made by EI?

Ive scored a bunch of these NOS tubes a while back, thinking they were possibly made by mullard blackburn as the crimped glass and etched codes appeared to look the same as blackburn codes, but upon further inspection the codes dont match and seeing smooth plates made me think they looked like telefunken construction.

After googling the codes on some of the tubes (most of them start with 2A1) and end with 06A or 06L, it looks like they are early EI tubes, despite "made in england" stamped on the glass.

If so, im guessing these are pre-war EI tubes from the 1970's?
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Old 7th March 2018, 08:13 AM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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If they were made in England, they would be printed ECC83 or have their CV number if Military. 12AX7 is not a UK form of printing.
They will be stamped Made in Great Britain, if indeed British.

Type ECC83 was first introduced in 1954. Ref; Valve Museum.
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Old 7th March 2018, 09:42 AM   #3
nzoomed is offline nzoomed  New Zealand
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Quote:
Originally Posted by JonSnell Electronic View Post
If they were made in England, they would be printed ECC83 or have their CV number if Military. 12AX7 is not a UK form of printing.
They will be stamped Made in Great Britain, if indeed British.

Type ECC83 was first introduced in 1954. Ref; Valve Museum.
Not 100% true, ive seen many Mullard tubes with 12AX7 printed on them, usually these are for export market and usually you see ECC83 beneath.
But your right, Mullard always used Great Britain stamped on them.
However I have seen some rebranded tubes from the 70's that were made in the blackburn factory but would have 12AX7 stamped on them.

Ive seen other millitary ones from Mullard also with CV492/12AX7 out there.
Anyway, im confident these are EI tubes, anyone farmiliar with EI codes?
Im interested to know when they were made.
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Old 7th March 2018, 10:37 AM   #4
DF96 is offline DF96  England
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More pictures and some examples of the complete etch code would help us. The later Ei valves used Philips etch codes; the code for Ei was a semicircle with a dot at the centre (IIRC). However, your suspicion that these are Ei may be correct.
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Old 7th March 2018, 10:50 AM   #5
nzoomed is offline nzoomed  New Zealand
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Originally Posted by DF96 View Post
More pictures and some examples of the complete etch code would help us. The later Ei valves used Philips etch codes; the code for Ei was a semicircle with a dot at the centre (IIRC). However, your suspicion that these are Ei may be correct.
2A1
06A

is all I can see on the tubes, they dont show up well in the camera also.
On some tubes they are not very readable, but im confident they are very early Ei tubes, which is a good score at $10 each
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Old 7th March 2018, 02:45 PM   #6
DF96 is offline DF96  England
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That code does not seem to be a Philips one, although the glass seams imply Philips tooling.
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Old 7th March 2018, 07:47 PM   #7
nzoomed is offline nzoomed  New Zealand
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Originally Posted by DF96 View Post
That code does not seem to be a Philips one, although the glass seams imply Philips tooling.
Im pretty sure the EI tubes used philips tooling for the glass and telefunken for the plates etc, these look exactly like an EI inside, but i am trying to work out the date on these, probably 1970's im guessing.
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Old 7th March 2018, 09:05 PM   #8
w5jag is offline w5jag  United States
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In the United States, "made in England" was usually ( fraudulently ) affixed to east German or USSR made tubes, possibly other eastern bloc countries, as an end run around legal restrictions.

However, all of the rebranded Ei tubes I have seen are plainly marked "Made in Yugoslavia". Perhaps they were insufficiently communist, or there were other considerations.

That said, I have in my hand a "National" brand, dual marked 12AX7A/ECC83, Made in Yugoslavia, that looks identical to your tube - Phillips style glass, Ei ( Telefunken ) style plates, but all of mine have the dot and semi circle factory code etched on the glass.

I believe your tube is an Ei, for better or worse.

Win W5JAG
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Old 7th March 2018, 09:49 PM   #9
nzoomed is offline nzoomed  New Zealand
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Originally Posted by w5jag View Post
In the United States, "made in England" was usually ( fraudulently ) affixed to east German or USSR made tubes, possibly other eastern bloc countries, as an end run around legal restrictions.

However, all of the rebranded Ei tubes I have seen are plainly marked "Made in Yugoslavia". Perhaps they were insufficiently communist, or there were other considerations.

That said, I have in my hand a "National" brand, dual marked 12AX7A/ECC83, Made in Yugoslavia, that looks identical to your tube - Phillips style glass, Ei ( Telefunken ) style plates, but all of mine have the dot and semi circle factory code etched on the glass.

I believe your tube is an Ei, for better or worse.

Win W5JAG
Interesting, ive never seen a single EI tube with their logo etched anywhere, mind you these were all later tubes with it painted on which as usual rubs off easily.
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Old 8th March 2018, 06:32 AM   #10
dewy1 is offline dewy1
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thats an Ei tube!




2A1 ist the Ei factory for ecc83/12ax7 tubes


3A1=ecc81/12at7


a semicircle with a dot is the ei factory code


i newer saw an ei tube code list ,the number 6 can be anything between 1966-86!

A and L are the months i guess


this is from the EI Website:


"Ei RC" operates as a subsidiary of Elektronska Industrija (Ei) Holding Corporation, Niš, Yugoslavia. The factory has been founded in 1951 using Telefunken technology. In 1959 Philips technology had been adapted and production was mainly devoted to the radio and TV tubes. There were 126 tybe types (NOVAL, OCTAL, MAGNOVAL) in production with overall capacity of 12 millions pcs/yr. In the mid eighties this production programme has been abandoned due to the technological obsolence and lack of the market.


dewy1

Last edited by dewy1; 8th March 2018 at 06:54 AM.
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