Which ECC? tube

Dear Radio friends,

I have half a dozen used but working ECC?? (Double triode) tubes. Unfortunately all type printing texts have disappeared but I found some factory codes: 1) ∆ (delta1D3, 2) ∆4D4, 3 )∆0J2. I am not familiar with factory codes and therefore would be glad if somebody could recognize from the codes the type of the tube. The glass bulb has the same size as example of ECC85. Look at the picture.

For example Avo Mark4 tester with settings UA=150V, -Ug1 2V gave average values of Ia= 15mA and S 10mA/V.

I would be happy for any hints what tube type this might be.

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Dear Mr. Nyholm,

the factory codes from your double triodes shows the factory and the production date:

Δ0J2 Philips Copenhagen, date 2nd week from October 1960
Δ4D4 Philips Copenhagen, date 4nd week from April 1964
Δ1D3 Philips Copenhagen, date 3nd week from April 1961

In the production date, the decade isn't sure.
Usually in the Philips code, there should be a second row of signs which contains the tube type and the issue.
Please look for it.

The apparent comparison shows a relationship to E88CC or ECC88.

Best regards from Munich, Bavaria,  H.-T. Schmidt

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Dear Mr.Schmidt,

Thank you for your guidance. On my used ECC?s just one has a second row but hard to read. Markings might be as: first row OJ 5 (or S) and second ±2J.
Anyhow, I found one brand new Philips ECC88 with type printing one it. Mechanically the tube's electrode construction looks to equal with my "used" ones.This tube has code rows as GAE and ΔOE1.

What was the primary application of the ECC88s (TV tuner?). Is it possible to use these as replacement for (hardly available)  ECC85 in FM front end?

Munich is a nice city, I used to visit there many times during my "working era".

Best regards

Ake

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Hello Mr. Nyholm,

0J5: there is no O but a D – DJ5 = PCC88 and 5th edition
±2J = manufactured in october 1962 by La Radiotechique in Chartres, France

and

GAE = ECC88  (E = not clear)
Δ0E1 = manufacured in may 1960 by Philips Copenhagen

The ECC88 were widely used in testing and measuring equipment for electronic engineering.

Have a nice sunday,  H.-T. Schmidt

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Dear Mr Schmidt,

Thank you for your information. It was good hint to check if some of my "used tubes" are type PCC88. I did notice when tested with Avo Mark4 (Uf 6,3V) that there was some slowness to reach final Ia and S (mutual conductance) readings.

Best regards
Ake

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