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Who can identify this radio and the valves

Ernst Erb Jürgen Stichling Bernhard Nagel 
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Forum » Radios and other type of sets (Physics) etc. » Devices: rare or unknown or self made » Who can identify this radio and the valves
Nicolaas van Dijk
Nicolaas van Dijk
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06.Mar.16 18:39

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I bought a radio at the flee market in very nice state. After some investigations I saw that the RF choke was missing, only the base was there. So I mounted an RF chocke of approx the same date at the base of the old one. Surprisingly, all valves were close to 100 % and both AF transformers were OK.

Testing did not discover any problems, and after supplying 3,6Volts at the filaments, 20 Volts at the RF HV, and -3V at the negative and 50 Volts at the AF HV, the radion inmedeately worked very well. There are two connectors for the AF, one after 1 valve (headphones) and 1 after 2 valves AF, (LS) 

Total current is approx 2 mA. The filaments don't need to be turned up at all for a good reception. 

The type coilset I never saw, it is a Lebos unit. All valves are from the brand Radio Technique (Spanish) and have the brand name Radio Micro at the glass. At the top of the box, it says Radio Micro with the number R3836Q. May be a brand or a reseller.

I can't find Radio Micro or Radio Technique at the museum, but the build does remind me of French valves. Filaments are tiny and take approx 60 mA. It are "bright glowers"

The case of the radio is absolutely no Amateur work, or it must have been a vey good meuble maker. 

The frontplate is ebonite with a wrinkle finish.

Can anybody identify this radio or the valves?


Nicolaas van Dijk
Nicolaas van Dijk
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12.Mar.16 15:38

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I investigated a little more, and the valves are almost sure R24 types. But these are French and the box says Spanish. Also Radio micro is unknown it seems. 

A carpinter told me that the box is almost sure Brazilian rosewood, not a wood sort normally used by amateurs. But the radio has no brand, number of whatsoever. 

Because the valves, including a spare valve, all had there original boxes from Spain, may be the radio has been manufactured in Spain.

 When I bought the radio, there was a spare valve that looks like the R24. The radio has two R24 valves and I bought it complete with the spare valve. Now I found a card rolled up inside the box. It is of the company Sociedad Espanola Radio-Electrica, s.a. in Madrid. When sent this card, one can win various objects like a radio, loud speakers etc. The valve was a R24 but at the ballon was the name Radio Micro, wich also appears at the top of the box. The box has the brand name Radio Technique and is from the Spanish company as mentioned above. At the card there is an advertisement of Raytheon valves and one can win materials of other brands. So it seems that Sociedad Espanola Radio-Electrica isn't a french branch in Spain, it seems a real Spanish company.

The one that sent the most cards, wins. It is unlikely, especially in Spain in those years, that more or many cards were sent in a short time. So the card should be valid at least one yera or more. The validity expires in 1927, so the valve has been purchased in 1925 or 1926.

I think though that the transformers were on the market in 1928 for the first time.

A scan of the card is included

That means that the radio may be a very early Spanish private production with purchased parts, perhaps even a purchase case.


Can somone put some light at this subject?


This article was edited 26.Mar.16 09:12 by Nicolaas van Dijk .

Mark Hippenstiel
Mark Hippenstiel
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26.Mar.16 19:04

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Dear Nicolaas,

Regarding the tubes:

Those tubes are all French production. La Radiotechnique had a sales office in Spain for the distribution (and repackaging) of those tubes.

The type Radio-Micro is known earlier than December 1924, unfortunately I don't have information on file about the first appearance. Maybe some of the tube specialists have. Tyne has it for 1924, which seems reasonable.

The R24 we have shows the image of a Super-Micro. We don't yet have an entry for Super-Micro. The Super-Micro is new in December 1924, and it is derived from Radio-Micro, with a variable amplification coefficient of 15 to 20, for resistance-coupled amplifiers which I believe is not the case for this set (transformer coupled). But I'm going out on a limb here, my knowledge is shakey at best. They probably would still work..

At some point the more literal names were dropped in favour of a type, and old named tubes were made available with a type designation. To make confusion complete, the same (established) names were used in conjunction with different types.

Both types Super- and Radio-Micro are still sold under their names a year later, in December 1925. A price list from 1925 (month unknown) has a Radio-Micro type R36, in 1926 there is an updated version Radio-Micro R26D. Equally, there are two types Super-Micro, R15 and R24, in 1926.

The pictured tube on the card was made unter license of Raytheon, there were two types: V70 and V71. Sfer 14 is a model that went on the market in 1927.

The R3826Q could be a R3836D, perhaps you can verify this. The R38xx series was established along with the R18 series (the former for 3.8V, the latter for 1.8V heating) and they were only re-designated Rxx types - but the same characteristics. So this is just another (later) replacement.

Unfortunately, all these dates don't really help with dating your set. You have to keep in mind that early triodes are basically interchangeable, and the fact that new types were available doesn't preclude a) the availability of older types from the manufacturer and b) stock that was available at merchants even if the tube itself was out of production.

To the set:

You say the coil set is a Lebos unit, I've never heard of that. I seem to see a logo on the bakelite base, can you make a better picture of that?

With no maker markings on the set at all, it will remain difficult. The construction looks solid and professional all in all.

The transformers look like Philips type 4003 (ca. 1930), but my knowledge about this type of parts is limited. Another indicator for an earliest year can be the form of the CV to be seen on "interior3". Those came in use around 1925/26 iirc.

So far, everthing points to a French production. You might want to investigate the coil set brand further, and look at the brand of resistors. Of course, the set can also have been built in Spain using French parts...

I hope that helps a bit. Perhaps someone with more knowledge can still contribute something.

Best regards

Nicolaas van Dijk
Nicolaas van Dijk
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31.Mar.16 20:14

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Hello Mark

Thankyou very much for the extensive reply. Very happy with it

About your question, I made a photo from within the radio of the coil set. The name was hard to see because it is hidden below the bars to move the coils and was quite dirty. At the foto the name appears to be lelos, not leybos. The number at all the boxes is R3836Q. The filaments of the valves ar 3,5 Volts (approx) Above that voltage there hardly any increase in emission. The filament of the first AF valve is in parallel with the CL104, which is 4 volts max. So both are adjusted with one variable resistor.

The card expires dec 1927 and most probably has a validity of 1 year min. or so. Very unlikely that people sent in more cards in a shorter time in those years in Spain. That means the the Raytheon valve should be available end 1926. Is that a valid conclusion?

There is only 1 resistor, the grid leak. It is a Loewe GMBH vacuum resistor of 8 MOhm 

The grid couplig capacitor is an Aerovox of 250 pF

Seems a radio with quite an international series of materials.

The Philips transformers have a primary resistance of approx 2800 Ohm and a sec. resistance of approx 50 kOhm

Kind regards