sra: 384V (384 V); Radiola

Hello Tube Radio Friends! In my recently acquired Radiola 384V (made by Svenska Radioaktiebolaget) the tube line up comprises of MEK2, MEF5, MEBC3, MEL3, MEM1 and MAZ1. What does the "M" standing for in type number of the tubes? Also there is sticker saying that my set is made in 1938, not 1945. regards Lars-G. Lundelin

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Dear  Lars
Good question!

Most members dont know:
If you click the link "Suggest change" on the model page you will get the history of the model - if there is one. In this case one can see that Jörgen Svensson did suggest this model. Up to that time, February 2006, we thought that the common tubes in the European system should always be written "the official way". Therefore we did not allow TEK2 (for Tungsram) or in this case MEK2 and changed to the normal EK2.

Naming a common valve in a different way was done by some factories. Here it is Marconi-Osram who used the M - probably for export only. Then I believe we should put in those tubes and give them the relation = (Equal) to the common ones, since we did this for Tungsram (and probably others).

The next step would be to upload photos ..

And then to change back thos tubes on this model.
At the same time it would be good to have the year correct, which is 1938/1939. I don't think that after the war these tubes were still named individual. The first reason for naming differntly was to prevent buying spare tubes or replacement from other makers ...

Thank you for questioning. Now we can get good solutions ;-)

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Thank you Mr. Erb for this interesting information. I will upload pictures of all these tubes in question as soon as possible. Regards Lars-G.

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Dear Lars

You can now upload the pictures to the valves (tubes). We are not yet really sure if it is really Marconi-Osram wh produced them. By having more details on the valves we might find out.

Can you also do  achange suggestion on the model - to put in the "special" valves?
Thank you.

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Dear Mr. Erb, I've been searching for information about these tubes and still waiting for answers from a couple of "tube specialists" to see if they have something to tell. Within 2 or 3 days I'll upload the pics. Best regards and Easter Greetings! Lars-G.

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Dear Lars and Tube Experts,

Following your helpful pictures, as suggested, you can upload to the M coded ones any time!      I have also examined my very few types and believe that yours are indeed Mullard/Philips tubes, but repainted and remarked with an M in front of the original tube type.

I have an EBC3 with silver coding 571 7 7BX in silver  paint on the base.  Yours has 571 6 in Silver.   In the Mullard/Philips coding the first 2 or 3 digits give the tube type, other digits are batch and date references.   This confirms your MEBC3 as a Mullard/Philips.

As I only have one AZ1 and one EL3 easily available, I have not found any agreement with your codings on the pins/tabs.  Mine are both Mullard and are coded F81 B6D and 1073 BU etched on the glass.  

I would ask any collectors with EL3, EF5, EK2 or AZ1 tubes to please examine and report on any markings on the pins and/or printed codings together with their manufacturer.  This should enable us to categorically define the origin of these imported and relabelled specimens!

Best regards and a Happy Easter to all.

Roy

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Dear Lars
I changed the valves now since Roy has introduced them. I also added the MEM1 and I hope this was not left out by intension (non existence) - otherwise I will delete again and change the model back for EM1.

Thanks to Roy we are now certain that the "M-valves" have been produced at Mullard/Philips and since those models carry MO-Valves (Marconi) it is pretty sure that my assumption above is valid.

Since we often can not tell which company has really produced a valve and since producers and wholesalers did often ask for other marking or even painting we put in the maker which is marked if it is an other valve name than the ordinary. In this case we can put in Philips as developer but Marconi as brand - if we know for sure. Roy will surely do this when he is certain of that. I wonder if we find some more types of "M-valves".

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Dear Ernst, Lars,

Indeed branding and manufacturer are difficult to separate and I agree the only way that we can operate with tubes and radios is to enter them with the device name and the "supplier" name that is on the device and then add information as to their origin if this becomes available.

I have done a little more research and have so far found that they were restricted to Sweden and to Radiola.   In the model 490 as late as 1949 it used MDK40, MDAF40, MDAF41 and MDL41.   I also have evidence of an MEL5 in the red range.  These I shall enter as new Marconi tubes with a caveat.  

The only firm evidence that I have is that Lars'  MEBC3 is a Philips/Mullard.  The manufacturers of the others are presently unknown.  I would therefore ask that any collectors with EK2, EF5, EL3, AZ1 or EM1  look and see if there are any codes on them - these are either etched on the glass, written on the side or under the base and/or stamped on the contacts.   We can then compare with the M series codes to determine their true origin.  

With kind regards to all

Roy

P.S.  Update!

1. A further examination of many of the Swedish Radios indicates that only SRA/Radiola used the M designated tubes.

2. Looking at a number of the schematics for the Radiolas shows that the tubes on the diagrams are marked as M-types but we have these listed as the "normal" types in the radio data page.

3.  The following types were found:-

In 376LV:-     MEF5  MEK2  MEM1  MEBC3  MCL4  MCY2

In 510:-          MDK40  MDAF40  MDAF41  MDL41 

In 1503V:-     MECH42  MEL41  MAZ41  (but the 6BA6 and 6AT6 are not prepended)

In 512LV:-     MUCH42  MUF41  MUBC41  MUL41  MUY41

In 1514V:-     MECH42   MEM34

This would seem to be evidence of existence of tubes MARKED with these designations (not only labelled on the circuit) considering the physical evidence from two sources.   It would also seem to indicate that these radios at least,  were originally fitted with the M-range tubes.  Most radios now in existence would have been changed to the standard designated tubes.   

At least a comment on the radios above may be appropriate even if the tube line-up is not modified to ensure originality.     Alternatively change them to the M-type, but since the majority of radios do not have schematics loaded there will be a differentiation.  

Kind regards to all,    Roy  

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Dear All,

I have in my collection a Radiola  type 472LV (Svenska Radiobolaget, Stockholm /LM Ericsson). This model was produced in ~1950 and is equiped with Marconi tubes: MUCH21, 2x MUBL21 and MUY1. It is a AC/DC (universal) model. Place of production ??

Best regards

Ake

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Dear  all
I like very much what has come out of Lars' first post. Amazing how long this story about the "M-valves" was going on. I would have beleived that it would have stopped after the WW2 - but no!

I wonder if we will really be able to have solid proof that Marconi themselves manufactured some - but here it does not matter - the brand matters.

Original tube line up on models:
I beg you to change models to the original tube line up (where we know) and to put in some words, specifying the "normal ones" in the notes of these models. The first because - where we can - we show the original line up and not the replacement. There we should be different to even other books which only look at the market situation when original tubes were not anymore easily available.

The notes have to be put in because probably most of the sets show the "normal designations" and owners don't see the original schematic - but the tubes. That's one reason - the other that members "who know better ;-)" will change back otherwise - and so on ...

I wonder if some of the sets (models) show the original tube line up printed somewhere. Only then the market impact (to buy the marconi tubes instead of others) would have been great.

The whole story shows also that only an international mix of members can get such results - or the "locals" for themselves. Local knowledge is very essential when getting to details. I'm glad that we are now 3865  (plus 84 who did not login yet) members from 66 countries.

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Dear All,

Yes this thread has indeed run a long way since Lars' initial apparently simple post!  In fact a lot is not really related to the specific model and is of a much more general nature.   Move?

We now list tubes under Brand rather than Manufacturer as quite often we cannot be certain of the manufacturer.   There are a number of ways that this Brand/Manufacturer uncertainty can arise and sometimes be resolved.  My experience is mainly with the British tubes so my examples are taken from personal examples; no doubt you will be able to add to them.

1.  Brands within a Manufacturer.  An example is the UK General Electric Company.  Initially the branded tubes "Marconi" . In the 1950s they branded tubes "Osram" for supply to the British Commonwealth and "GEC" for supply elsewhere.  Both were manufactured by the M-O Valve. company.

2.  Brands within a Group.   Examples are Philips/Mullard, Thorn/Brimar and GEC/(English Electric + M-O. Valve).   The Philips/Mullard  link is much tighter as they both manufactured tubes of the same name and specification and fortunately they usually permanently marked their items so as to permit identification.  Since most common tubes were manufactured by both Philips in The Netherlands and by Mullard in the UK we designate these as "Common European production".

3. Cross-Branding by Distributor.  This is where a supplier imposes his own brand.  Zaerix, 6202, RS and Pinnacle.  The distributor bought tubes from various sources and rebranded them.

4. Cross-Branding by Manufacturer.  This arises from a number of reasons.  Sometimes a manufacturer would not have stock so bought in from another manufacturer.  A manufacturer also wished to offer a special tube that he did not manufacture. 

5. Cross-Branding by Radio Manufacturer.  It is in this rare category that the Swedish Marconi branded tubes fall.  SRA was formed out of ASEA, AGA and Ericsson; Marconi bought into SRA in about 1921 and retained this until about 1970.  The Swedish tubes such as the MEF3, MEBC3 etc are all marked "import" confirming that they were rebranded in the country of import.   

The above is a brief summary - a few examples that I quickly found in my collection :-

EF91  Mullard branded GEC

810  Radiatron branded Marconi

3B28 Chatham branded Mullard

PCL83 Mullard branded Mazda

ECC88  Mullard branded Philips  (type 2 - others type4)

It would be of interest to know whether Jacob's splendid samples have any coding on them that could throw any light as to their origin.   (We have only been able to trace a MEBC3 to Philips/Mullard so far!)  Would he also agree that it proves that they were branded as Marconi rather than manufactured by them? At least until proved otherwise!

Thanks also to Åke for the information on further M-types.   It would seem to confirm that most SRA radios had Marconi-branded tubes over a long period.  Again any information on the coding of these M-types would be beneficial. 

Finally a note to add to Ernst's post.   It seems that we are approaching "critical mass" whereby the museum is becoming capable of functioning as a serious research tool.  Not only the spread of members but the quantity of data makes it possible.  Use and usability will increase as the data bank becomes fuller!  Thank you for making it possible.

Kind regards to all,

Roy

 

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Dear Roy,

I think, there are no usefull codings on these Marconi- tubes.

The MDM21 has a "F" printed on the bottom of its base, as well as on the MUF9 is something printed, which could mean "UF", but the "U" is almost illegible.

 

I attached a picture of the  MUF9 box here. Apparently it was made in Sweden, since on its lid is printed "NORMANS A.B." as the box maker.

 

Best Regards, Jacob 

Attachments:

• MUF9_box (19 KB)

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