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ID = 49353
Brand: Dario (tubes) - voir aussi La Radiotechnique
Tube type:  Triode, vacuum   Universal 
  Ca. 1925 up to 1945 rare.
Identical to RT655
Similar Tubes
Other base:
Other base and other heater:
First year 1927 Saga of the Vacuum Tube, Tyne pp 404-406

Base Europe 4-Pin B4 (Eu A, E, 4A) 1914 2 Sidecontacts.
Was used by Radio/TV-reception etc.
Filament Vf 0.6 Volts / If 1.5 Ampere / Direct / Specified voltage AC/DC

The brandname is RT-Dario. This is an early AC tube, dated 1927.

Information source - - Manufacturers Literature   not dated

f_dario_rt655_sockel.png RT655: Dépliant Dario
Mark Hippenstiel

Just Qvigstad
RT655: own collection
Peter den Boer

More ...

Forum contributions about this tube
Threads: 1 | Posts: 5
Hits: 2445     Replies: 4
RT655, RT656, RT636, RT643
Peter den Boer

I have listed these tubes as "battery". But all of these tubes has a strange low filament voltage of 0.6 Volt.The firstPhilips AC tube was the C0805 in 1926. As the designation says, the filament voltage of this tube was 0.8 Volt. This was also a direct heated tube.

Could the RT636, RT643, RT655 and RT656 be early AC types?

Peter den Boer

Jacob Roschy

Hello Peter,

in the event that you have this «Radiotechnique» advertisement sheet (with these tubes in yellow) in complete condition, from which you did cut-out the data of the individual tubes, - the answer to your question might probably be found there.

If so, then please post it here completely, in order that someone can translate it.

Best Regards,


Peter den Boer

Well, my French is not that good, but the problem is that I did not look good. At the top of the attached page is printed  ... sur le réseau alternatif. Which means that these tubes are indeed AC tubes.

I also overlooked the note at the end of the page. Hier is written that these tubes have two extra side terminals. This is usual an alternative way to connect the filaments.

Sorry for the inconveniance. I will try to be more carefull.


Jacob Roschy

Hello Peter,

thank you for posting this valuable document. It's just a I expected, «fonctionnant directement sur le réseau alternatif» means something like «works directly on AC voltage».

As for this strange filament voltage of 0.6 Volt, there might very little else to be expected.

Btw., your attached data file RT636 has no contend =(0 kb), though the first data file RT655 has all it takes.

Best Regards, Jacob

Peter den Boer

Hello Jacob,

Yes there are listed two 0 kb files. But the download failed because the filzeseizes were to big (above 200Kb). I had to reduce the number of pixels te get under 200KB and keep it readable.If you are interested, hier are the other 3 pages.

Best regards, Peter


End of forum contributions about this tube

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