radiomuseum.org

 
Please click your language flag. Bitte Sprachflagge klicken.
  The thread rating is reflecting the best post rating. Have you rated this thread (best post)?

An overview of Italian vacuum tube manufacturers

Moderators:
Ernst Erb Otmar Jung 
 
Please click the blue info button to read more about this page.
Papers » Tubes and valves (history, technique etc.) » An overview of Italian vacuum tube manufacturers
           
Emilio Ciardiello
Emilio Ciardiello
Editor
I  Articles: 508
Schem.: 165
Pict.: 742
05.Nov.12 12:05
 
Count of Thanks: 59
Reply  |  You aren't logged in. (Guest)   1

Foreword

This is an overview of the known Italian vacuum tube manufacturers. I hope that it can be of some usefulness to the many collectors who want to know more, when looking at a vacuum tube of an little known manufacturer, maybe with a strange label glued on the bulb. Although fairly comprehensive, as regards the names of manufacturers, it is largely based upon memories and readings in the past, which may be incomplete and inaccurate. Any correction of the given information and any additional information are always welcome.

Prehistory

We know from Tyne (*1) and from Franco Soresini (*2) that the Italian physicist Quirino Majorana had described since 1912 an electron tube, named ‘deviatore elettronico’, or electronic switch. Anyway, we must wait until the Great War, 1915 to 1918 for Italy, to find a true production of vacuum tubes, intended for military purposes. According to Soresini, the very early Italian tube manufacturer was Ing. Prola in Rome. His double filament triode was used through the Great War by Italian Army Engineers Corps in the telegraphic receiver known as ‘Epuratore Bardeloni’.

Around 1917 we see another triode, used in audio amplifiers, intended for listening to phone messages of enemy troops. The ‘Gorizia’ triode, designed by Quirino Majorana, was built by the firm ‘Giuseppe Longoni’ in Genoa, a manufacturer of electric lamps. Soon after the war, the firm Longoni was bought by Marconi and closed, to avoid their competition.

In the early twenties we find the well known ‘Zenith’ in Monza, near Milan, where Ing. Del Vecchio started the production of his DV2 (Del Vecchio 2) triode. For some years, Zenith was the only known Italian source of vacuum tubes.


The radio industry in Italy and the Fascism

In the twenties in Italy we find a lot small radio manufacturers, often anonymous, to avoid the tax then existing on each set in favor of the radio broadcasters. Most of them were just small workshops or artisans, which used components and even tubes from other countries, French, Germany, Great Britain or United States. In the late twenties over than 60 radio manufacturers were sharing a very small market, which would grow only later, in the thirties, with the introduction of the popular models wanted by the fascist regime. ‘The village must have the radio’ was the slogan of the regime in 1931. And soon the best prototypes submitted by ten Italian radio manufacturers were selected to built the standardized ‘Radio Rurale’ models, supplied to communities, schools, parishes and other associations in even the smallest municipalities across Italy. ‘Radio Rurale’ was followed soon later by the models ‘Radio Balilla’ and the improved ‘Radio Roma’, intended to spread the radio into the homes of private citizens.  

In 1931 Italian government also intervened in favor of the domestic radio industry, imposing heavy customs duties on sets and components coming from abroad. Here some customs fees decided for the most relevant parts:

Customs fees on radio parts and tubes
Receiving sets equipped with 1 to 5 tubes Lit   80   each
Other radio sets Lit 100   each
Vacuum tubes weighing up to 80 grams Lit   10   each
Vacuum tubes up to 150 grams Lit   22   each
Vacuum tubes over than 150 grams Lit   50   each
Speakers, resistors, electrolytic capacitors Lit   50 per kg
Other radio parts Lit 135 per kg

To give an idea of how these fees could be high, we must remember that in those years Italian lira was changed at par with U.S. dollar. The pay of a sergeant was around 25 Italian liras per month, while a corporal just earned about 3 liras per month.

The customs fees had to be added to the tax already existing on vacuum tubes and lighting equipment. This tax was prepaid with each tube and was proven by a stamp or by a seal, as in the figure below. Tubes supplied to the armed forces were exempted from the fee, the exemption being displayed on a stamped label.


 

There were all the favorable conditions for a considerable growth of the market and, at the same time, for the growth of domestic industries. To continue business in Italy, foreign manufacturers were forced to sell production licenses to Italian companies or to open here their own production plants. In this scenario, in the thirties new vacuum tube manufacturers appeared in Italy.

- FIVRE was the largest all-Italian company, founded in 1932 in Pavia by Magneti Marelli to produce vacuum tubes under Radiotron license. For a while their tube supplies to the parent company, Marelli, were characterized by distinctive violet-glass bulbs. In their ads they evidenced the equivalence of their tubes with those manufactured in the United States by RCA. ‘RCA – FIVRE: From America to Italy, different brands but the same quality’ said an ad from a 1934 magazine.

FIVRE ads and boxes

 


- Officine Marconi Genova was the longest-running company in the manufacture of vacuum tubes. It was related to the many activities of Marconi in Italy since 1906, in the wireless communication, in broadcasting and in maritime radio-telegraphic traffic. As tube supplier it operated from the very early twenties, probably only as importer in the first years, up to about the mid seventies, when the production of vacuum tubes declined rapidly. Few years before, Marconi had bought the factory of ATES-RCA in L’Aquila, where it moved the production of receiving tubes.

 

 


- Philips had started a commercial business in Milan around 1925, importing vacuum tubes and everything else from the Netherlands. In 1928 it bought a lamp manufacturing company in Alpignano. Anyway no evidence can be found of vacuum tube productions in this plant and anywhere in Italy until 1936, when Philips bought the Zenith tube factory in Monza. It is reasonable to assume that in the early thirties, in order to save customs duties, their radio factory in Milan could somehow rework partially processed tubes, supplied in bulk from the mother company. This policy can be presumed by inaccuracies found in some ads. In the ad below they introduce the new AK1 converter. Unfortunately they show a CK1 with side-contact European base and assorted subassemblies, clear sign that they knew the existence of the new tube, but had not yet received the right electrode subassemblies and basing details from their mother company.

Ads of the Philips radio facilities in Milan and of the AK1
 




- Telefunken – No useful information can be found about the start of tube productions by Telefunken/Siemens in Milan, Italy. Supposedly such production began in the first half of the thirties, also including processing of semi-finished bulbs and components coming from Germany.




- Zenith was an old tube manufacturer based in Monza, as we saw before. In the early thirties it listed a full line of receiving and power tubes, including European and American types, as well as proprietary ones. It was well introduced in military productions, even as second source for Marconi, Philips and Telefunken types. In 1936 it was bought by Philips, even though the brand continued to survive at least until WWII.

Zenith ads around 1934



Some notes

In the thirties Italian government pushed for a high degree of standardization in electronic sets at any level. We see military radios based upon a single tube type in every sections. Tube manufacturers were asked to supply interchangeable types. Even if equivalencies are often hidden, due to the different tube coding systems adopted by each manufacturers, usually we can find two or three sources for each tube. In many cases equivalence was simply based upon the basis of 3F criteria, ‘Fit, Form, Function’, with no sharing of production details. A clear example is given by the four known Italian versions of the RS31g Telefunken tube, the Telefunken Milano RS31, the Zenith W31 , the Marconi Genova MT31 and the FIVRE 3C70. The four tubes look quite different, the Zenith one lost its cap, in colors, materials, surface treatments and even in the visible amounts of asbestos. Here a picture that shows thumbnails of the four tubes, thanks to the courtesy of Alessandro De Poi for the RS31 and of Sigurd Hauschild for the W31. Special thanks to Norman Wilson, N6JV, for the info on the 3C70, shown in his site.



Effects of the sanctions from 1935 and of the raw material shortages during WWII

Starting from 1935, with the sanctions imposed to Italy by the League of Nations, the electronic industry began to suffer a severe shortage of strategic materials, copper, tin, nickel, even rubber and any raw material imported before. Until the outbreak of war, something could still be purchased in U.S. on the basis of the ‘cash and carry’ policy, introduced by F. D. Roosevelt since the ‘Neutrality Act’ of 1936. Unfortunately this was not enough to cover the needs of the industry. Italian government promoted a policy of autarky. The entire industry, including the electronic one, was asked to become independent, as far as possible, from imported materials.

In this context must be evaluated many productions of Italian tubes, derived from foreign types and yet somehow different from their prototypes, as per construction details or performances. No traces remain today of the solutions used by each manufacturer to ensure their productions, even in shortage of several materials. Countless solutions were proposed and each solution could change, batch after batch, depending on varied availability over time of raw materials. We know that for the power distribution in Italy wires were used made of aluminum ribbons wound around a steel core, to replace copper. On the contrary, pure silver was used in America to replace copper in RF coils, when in 1941 it began to be scarce. Today we can just guess some of the solutions, carefully examining each vacuum tube build in those years. The four variants of the RS31 above even give examples of how different materials were used by their manufacturers, probably at different times.

Of course, we have to assume that each link and each exchange of information between Italian Marconi and its parent company in England ceased at all at the outbreak of the war. The same certainly happened between FIVRE and RCA after Pearl Harbor and maybe even before. In the meantime, business relations with German manufacturers had increased, to the point that new Italian tubes were either entirely ‘autarkic’ Italian designs, or were copies of Telefunken or, at least, of other European types. A mix of the two options can be found in many tubes of the family WE xx.



Manufacturers in the after war

After the war we find three tube manufacturers still surviving: FIVRE, Marconi and Philips. No evidence of the reopening of Telefunken vacuum tube lines can be found, despite the relevant presence that Siemens retained in many fields of electronics and telecommunication. The three manufacturers above were helped to rebuild their facilities destroyed by bombing, even thank to funds from Marshall Plan, also known as ERP, European Reconstruction Plan.

From the mid fifties, thanks to the growing market, we see the birth of new tube manufacturers.

ELSI, Elettronica Sicula, was founded in 1956 in Palermo, Sicily, by initiative of Raytheon and Machlett. For years it produced tubes for civil and military markets, cathode ray tubes and semiconductors. Since 1962 its production was fully qualified and tubes came out marked Raytheon or Raytheon-ELSI. In 1969 ELSI became ELTEL, Industria Elettronica Telecomunicazioni, a public owned company, dedicated to special tubes.

Around 1990 the plant was acquired by Alenia and continued to design and produce microwave tubes and components under the name ALELCO, ‘Alenia Elettronica Componenti’, until it became Galileo Avionica, still in business today.

Raytheon - ELSI ad and one of its NATO qualified tubes



Sicte, Pavia - Around the late fifties we find this company, probably founded by some retired FIVRE executives. SICTE was specialized in vacuum rectifiers and other power tubes for TV sets. They listed some quite uncommon rectifiers with separate diodes inside, designed for voltage doublers.

 



Magnadyne – This company was in business in Torino since 1922, when Paolo Dequarti, then just sixteen, began to build radios. Magnadyne started building its own vacuum tubes in the late fifties. Magnadyne tubes were designed for optimum operation in the TV and radio sets sold by the several brands of the group. Tubes were identified by proprietary codes and usually were not interchangeable with common European or American receiving types, sometimes just for different screenings, but even for different ratings or pinout. The code was simple: a group of numbers for the heater voltage, a letter for the number of electrodes and a type identification progressive number.

This is the meaning of the letters used in the code:

D = diode, signal. (Sometimes D was also used for Double)
E = heptode
F = beam tube, beam tetrode
P = pentode
R = rectifier
T = triode

Multiple section tubes might have more than one letter. Here some examples:

6T1 – was an UHF triode, similar to 6AF4A
6T26 – was a twin triode, equivalent to ECC85
6TP6 – Triode-pentode, equivalent to 6BM8/ECL82
12P1 – was a pentode, similar to 12BA6
9TD35 – Triple diode – triode, similar to 9AK8/PABC80
25F7 – Beam power amplifier, equivalent to 25E5/PL36

As said before, any equivalence with tubes of other manufacturers, must be checked on a case by case basis, since Magnadyne tubes were designed or anyway screened for proper operation into given sets.

 



ATES RCA – Founded in 1959 in L’Aquila as ELIT, Elettronica Italiana, soon became ATES, Aquila Tubi Elettronici e Semiconduttori. The registered office was in Naples, the sales office was in Milan, the central management in Rome. In 1960 RCA entered into the shareholding, fully qualifying the production lines. Tubes made in the L’Aquila plant came out with the double marking RCA – ATES and were sold through RCA commercial channels. When, in the late sixties, RCA abandoned this market segment in Italy, Marconi bought the plant, moving there its production of receiving tubes.

 



In addition to the said manufacturers, we find two CRT makers, Eurovideo/Indesit and Videocolor.

Videocolor, Anagni (FR), was founded in the sixties by RCA, that soon abandoned this market segment in Italy. Around 1970 Videocolor was bought by the French Thomson. In the golden age of cathode ray tubes, its production reached a peak of 2,5 million units per year.


Indesit – Eurovideo, Teverola (Caserta)

Eurovideo, Teverola (CE) near Naples, was founded in the sixties by Indesit, a large industrial group with 8 factories, to make B/W CRTs needed for its low end TV sets. Eurovideo also listed a family of green or yellow screen CRTs for computer use. The line was closed around the mid eighties and the production equipment moved to China.



References;
1*) Tyne, Saga of the Vacuum Tube
2*) Soresini F., Di Tubo in Tubo
‘L’Antenna’ magazine: some issues of the early thirties
‘La Radio per Tutti’ magazine: some issues of the early thirties
‘Selezione di tecnica radio – TV’ magazine: some issues of the early sixties
Ventimila Valvole, CD by Leonardo Mureddu and Stefania Atzeri
1968 GBC Vacuum tubes and CRTs price list

This article was edited 08.Nov.12 06:15 by Emilio Ciardiello .

  
rmXorg