ACH1 (ACH1) - produced with C7A or P8A base

ID: 88356
This article refers to the component: To the tube/semiconductor

ACH1 (ACH1) - produced with C7A or P8A base 
18.Jan.06 22:55

Robert Sarbell † 22.3.22 (USA)
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Robert Sarbell † 22.3.22

Tube administrators and members,

I have just recently bought some early tubes for the Philips AL161, and find there appears to be the Telefunken ACH1 produced with a C7A base, and also a Telefunken D.R.P. tube with the P8A base - the marking is clearly NOT the ACH1C tube that is shown with the ACH1 technical data.

I have seen many interesting posts related to the multitude of tubes - and even some from Herr Wolfgang Bauer which depicts the very interesting, and apparently occasional, non-standard tube types.

I realize there were many tubes produced with the P8A base; however, it appears as though most of them were the variant type ACH1C.

Robert Sarbell

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ACH1 with non-standard base? 
19.Jan.06 01:11

John Turrill (GB)
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Dear Robert,
                    over the years I too have found much confusion finding valves with bases they're not listed as having; quite recently I found a source of 6E5 "magic eyes" with an International Octal base, and I can't find any listing for this. (they're also quite short & straight sided - "G/T" almost)

(My apologies; I obviously didn't know how to use the RMorg search facilities properly - I've now found the 6E5GT is listed - I'll try and upload a photo soon as possible, John, 26/1/06 )

  I'd guess the reason for many such anomalies might be that if a large radio manufacturer needed a std. valve type, but preferred a different base, or size, shape etc. then if the order was large enough maybe a valve maker could be persuaded to "do" them a special run.
(perhaps someone knows whether this happened?)

   Another reason, at least here in G/B, was that in early days when the max. no. of pins was 5, all of a sudden came the 7pin base, and many of the 5pin types were produced with just a change of base (same type no.)
    Sometimes valve sellers didn't seem to appreciate this, and much aggravation must have been caused when a new valve didn't fit!

Best regards,
                     John Turrill.

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P8A base for a Telefunken 
19.Jan.06 07:42

Ernst Erb (CH)
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Ernst Erb

Dear Robert
We call this tube ACH1_Tungsram. Because it was Tungsram which introduced this base to the ACH1. If you look for a tube, please write only the standard designation to the "Search for a tube/valve" on the main tube page (tab "Tubes"). You then find the different makings. Normally they are also interlinked on the tube page but we are not through this process.

You look for a 6A8GT - dont write this but 6A8 and you will get 8 different tubes: 6a8 (russian), 6A8 (metal), 6A8G (glass), 6A8GL (glass tubular), 6A8GTX, 6a8m (russian, a small glass), 6A8MG (French type metal shielded) and 6A8V.

Back to your ACH1 with a P8A base:
Please go to ACH1, select the ACH1_Tungsram.
Then click "Add information to tube". Then click "Varaint".
Please as a name write "ACH1 with base P8A not Tungsram" to the English part.
Do only write a text to the English field "Text" if there is a pregnant description, something of "worth for years".

Afterwards you should be able to load up your picture to the ACH1_Tungsram-variant. We might have to change name for this tube - e.g. to ACH1_Topfsockel or ACH1_P8A. It might be that someone has first to activate your variant, so please do it now and see if you can immediately post the photo or not and tell me. It is adviseable to photograph the tube right from the front - in your case from the "top" and to have the picture in a bigger size so one can read everything.
Thank you very much for this effort - if that is possible.

Dear John
For a new valve please tell one of the tube admins to create this valve. They are listed on the tube page. If it has the same designation as an existing one then propose an "underline-tube" which means a short distinction of the "normal type" by adding an underline and name (see above). But if it is just different in appereance or a special maker or so you do what I proposed to Robert if you are so kind.

With this procedure we get an ever better database and understanding. Thank you for helping to this goal. I know that we have here (again) a very special way to build up our database which is not always easy but I hope we have therefore also a very interesting one with direct and rapid crosslinks to similar, predecessor valves, successor valves, models, techn. data, first year on market, surrounding schematic (normal use), base connection, prices for NOS etc. 

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19.Jan.06 18:09

Jacob Roschy (D)
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Jacob Roschy

Hello Robert,


my congratulations to this find !

Even if you are not realizing, I'm firmly convinced this is the real ACH1"C" !


In the literature the "C" indicates, it's a special Telefunken ACH1 fitted with the P8A side contact base.


The quotation marks indicates the "C" is no official part of the tube designation. But on the tube itself, it was omitted, as the base is obvious. In later literature the quotation marks has been dropped.


Tubes with different bases without any indication on the designation were very common in Europe in the 1920s and occasionally in the 1930s, as in this case.

This remark is printed on a Telefunken tube list from 1939 an is related to the ACH1.

It tells, for replacement purposes for sets of the "Ostmark" and "Sudetengau" the ACH1 can also delivered with side-contact base, then called ACH1"C".

"Ostmark" and "Sudetengau" were the terms the Nazi regime used for Austria and the Czech territory.


Apparently this ACH1 side-contact version was already common in these areas before Hitler's "Anschluss" and occupation. Most probably this version was introduced by Tungsram there, AKA as TACH1.


But this caused confusion due to the base connections, which are different between the Telefunken ACH1"C" and the normal Tungsram (T)ACH1.

While the ACH1"C" has firmly the same wiring as the Telefunken CCH1, the normal Tungsram (T)ACH1 has the same wiring as the later Philips ECH3.


I can't understand, why Telefunken delivered their ACH1"C" as replacement for the Tungsram (T)ACH1, but with a different base diagram, where 3 connections are interchanged (gT+g3, g2+4 and aT) !


To solve this problem,- but to add further confusion too, - Tungsram also offered a side-contact version with the Telefunken- diagram !


Best regards


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19.Jan.06 21:37

Robert Sarbell † 22.3.22 (USA)
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Robert Sarbell † 22.3.22

Good Evening John, Ernest and Jacob. . . . .

Thank you so much for enlightening me about the tube specifics.

For John,
Our tube development did progress from 5-pins, to 6-pins, to 7-pins and then the 8-pin. Somehow the tube engineers could not resist counting by ones.

For Ernest,
The 6A8GTX version, based upon the article that was published by Sylvania in the NEW TUBES section of their Technical Notes in the November-December 1939, Vol. 8 No. 6, must have had the (ceramic base). Sylvania was introducing a 6A6X, 6J5GX, 6L6GX, and the 6V6GX versions.

For Jacob,
Is it possible that Telefunken had been "upstaged" by their competition; and decided they were going to identify the tube as they pleased. I believe one of our VERY prominent members, quite some time ago, related some similar thoughts to me regarding the choice of tubes within some early Biennophone models - the Telefunken tubes were not their choice.


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22.Jan.06 12:28

Jacob Roschy (D)
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Jacob Roschy

Hello Robert,


Thanks to your find, now we finally have an optical evidence of Telefunkens ACH1 side-contact-base version, which is called "ACH1C" when printed on paper or talked about.


We still don't know what the additional "C" means, nor how it came to its different base diagram, these are mysteries yet to uncover.


Though you cold do a big favor to us, if you make a nice picture of this ACH1, shown in vertical position and frontal view to put in the ACH1"C" page of the tube division.


Before the end of WWII Telefunken had an almost-monopoly for tubes in Germany. Competitors like Valvo and Tungsram were limited to a small share only. Telefunken prevented the introduction of tubes they didn't like, among them the Philips red series, as well as tubes like the Tungsram  ACH1 side-contact-base version.


After "Anschluss" and occupation of Austria and in the Czech territory by the 3rd Reich, these areas came under this Telefunken monopoly, which were free markets for tubes before.


Telefunkens endeavor then was to supply these before undesired tubes for replacement purposes, included this peculiar ACH1"C".


Best regards



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ACH1C with original box found 
08.Oct.06 22:11

Andreas Steinmetz (D)
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Dear collectors,

now I have found a Telefunken ACH1"C" in its original box. The date code is "tq", which means, that the tube was manufactured in June 1941. The tube does already have the newer design with silver metallisation, without "D.R.P.". It has the side-contact-base P8A with  the pinning of the CCH1. The tube is labeled "ACH1" without the "C". Very interesting: The box is labeled "ACH1L", but not "ACH1C"! I´ll add the photos to the ACH1C-page.

One more interesting detail: After having compared many old Telefunken tubes, I am quite shure that an old Telefunken tube with a small letter "p" near its label or at the bottom side of the base is an "Ostmark"-tube or it was Czech or Poland made. Who knows more details?


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