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ID = 3025
Brand: Common type Europe tube/semicond.
Developer: Mullard Wireless, London (see also Mullard Radio Valve) 
Tube type:  Vacuum Pentode   Power/Output 
Identical to EL33 = 6M6G = N147 = EL3NG = BVA264 = BVA267 = BVA265
Similar Tubes
Other shape (e.g. bulb type):
Normally replaceable-slightly different:
  6P25 ; 6PX6G ; EL33A ; EL33M
Heater different:
  PL33 ; PP6BG
Different connections:
Other base:
  EL11 ; EL3N
Multiple differences or of other kind:
First year 1938 History of the British radio valve [570]
Predecessor Tubes EL3N  
Successor Tubes EL41  

Base Octal (Int.Octal, IO) K8A, USA 1935 (Codex=Udo)
Filament Vf 6.3 Volts / If 0.9 Ampere / Indirect / Specified voltage AC/DC

With metallisation, connected to pin 1, or without metallisation

Tube prices 4 Tube prices (visible for members only)
Information source Taschenbuch zum Röhren-Codex 1948/49   

EL33: Courtesy Bureau Belper (De Muiderkring, Bussum), Scan Frank Philipse
Karel De Reus †

oc66.png EL33: RTT 1974 (Franzis) 13. Auflage
Martin Renz

Just Qvigstad
EL33: Manufacturer's Literature
Emilio Ciardiello

More ...
Usage in Models 1= 1938 ; 6= 1940 ; 2= 1941? ; 2= 1941 ; 2= 1942?? ; 2= 1945?? ; 2= 1945? ; 4= 1945 ; 1= 1946?? ; 3= 1946? ; 33= 1946 ; 3= 1947?? ; 7= 1947? ; 41= 1947 ; 6= 1948?? ; 12= 1948? ; 37= 1948 ; 4= 1949?? ; 6= 1949? ; 36= 1949 ; 5= 1950?? ; 5= 1950? ; 16= 1950 ; 1= 1951? ; 7= 1951 ; 1= 1952?? ; 1= 1952? ; 2= 1952 ; 1= 1953 ; 1= 1954 ; 1= 1955?? ; 1= 1992?? ; 1= 1992? ; 1= 9999

Quantity of Models at with this tube (valve, valves, valvola, valvole, válvula, lampe):254

Collection of



Forum contributions about this tube
Threads: 4 | Posts: 13
Hits: 2575     Replies: 0
Erreur sur le EL33 dans Sélection Rapid Tubes.
Michel Deluz

 Attention : dans Sélection Rapid Tubes des éditions ETSF, le tube EL33 est donné comme l'équivalent d'un 6V6, ce qui est une grave erreur. Le 6V6 est une tétrode à faisceaux dirigés avec une pente de de 4 tandis que le EL33 est une penthode pure avec une pente de 9.


Hits: 3798     Replies: 1
EL33 (EL33)
Júlio Branco

  Hello, Radio Friends members,

It will be that la válvula EL33 (Mullard) it is equivalent to the valve KT61, (Marconi).

Retired data the book in Spanish of the author R. J. Darkness. 1.ª edition November 1956.

Best Regards

Júlio Branco

Jacob Roschy

Hello Júlio Branco,

The EL33 (or 6M6) it is NOT equivalent to the KT61. This data book is not serious !

A Philips or Mullard data book would never make such recommendations.


The EL33 needs a cathode resistor of 150 ohms at least, while the KT61 needs a cathode resistor of only 90 ohms.

Without changing the cathode resistor the EL33 and the KT61 may never be used to replacing each other.

As a makeshift one can use a KT61 to replace an EL33, but the performance will decrease.

An EL33 should never be used as direct replacement for the KT61. Due to the wrong cathode resistor the EL33 will be severely overloaded and will give only low performance.


Best Regards, Jacob

Hits: 3405     Replies: 1
EL33 (EL33)
Júlio Branco

Amigos miembros,

Será que la válvula EL33 (Mullard) es equivalente a la válvula KT61, (Marconi).

Datos retirados el libro en español del autor R. J. Darkness.

1.ª edición Noviembre 1956


Com os meus cordiales cumprimentos


Júlio Branco



Jacob Roschy

 Hello Júlio Branco,


El EL33 (o 6M6) no es equivalente al KT61. ¡Este libro de datos no es serio!

El libro de datos de Philips o de Mullard nunca haría tales recomendaciones.

El EL33 necesita un resistor del cátodo de 150 ohmios por lo menos, mientras que el KT61 necesita un resistor del cátodo de solamente 90 ohmios.

Sin el cambio del resistor del cátodo el EL33 y el KT61 se pueden nunca utilizar a substituirse. Pues de expediente puede utilizar un KT61 para substituir un EL33, pero el funcionamiento disminuirá.

Un EL33 se debe nunca utilizar como reemplazo directo para el KT61. Debido al resistor incorrecto del cátodo el EL33 será sobrecargado y dará seriamente solamente de resultado inferior.




Hits: 10681     Replies: 7
EL33 (EL33)/ 6M6
Júlio Branco

Dear Members


This information can be very useful goes my dear friends of the radio.

The tube EL33 directly can be substituted by the tube 6M6.

Best regards

Júlio Branco

Roy Johnson

Dear Julio,

I have just seen that you also posted to the EL33, so I copy my comments made to the 6V6 below  as a caution.

"The 6V6 and EL33 are NOT equivalent!  A hasty note of warning!

They have the same base, connections and heater volts but differ considerably.  THe heater current of the EL33 is 0.9A compared with 0.45A for the 6V6.

More seriously the biasing requirements are different and could cause dangerous excess anode currents.  Replacing an EL33 with a 6V6 without changing grid bias would not be a good idea!

The power limitation on the EL33 is 9W whereas the 6V6 is 12W; the output impedance is different.

Whilst it may "work" to exchange these tubes it should not be done without circuit changes.

Regards to all,   Roy"


Also kindly act please on Mr Erb's request to remove "directly" in your posting so that there is no possible confusion!  We must be careful not to leave information that could prove dangerous to equipment or to people!  Thank you.

Kind regards,   Roy

Jacob Roschy
As Roy has already mentioned, the 6V6 and EL33 are NOT equivalent ! 
Since all data shown in the diagram are those for the EL33 or 6M6, which are fully equivalent to each other, it's most possible, the titel of this data sheet was written wrong. Instead of EL33 / 6V6 it should read EL33 / 6M!
6V6 and EL33 / 6M6 are very different in characteristics and performance. They should never be used as replacement to each other !
This is clearly obvious by comparing their operating data:
EL33 / 6M6
Anode current
Anode dissipation
bias Voltage
 - 6
- 12.5
Cathode resistor
Mutual conductance
Load resistance
k Ohms
Avoid to replace a 6V6 by a EL33 / 6M6 ! – This leads to low performance, use it only as temporarily makeshift !
NEVER replace an EL33 or 6M6 by a 6V6 ! – This will cause severe overload to the tube and to the circuit as well !
Applying the proper bias for the EL33 of –6 V only to the 6V6 will raise its anode current up to 80 mA, which will cause 20 W Anode dissipation !
Best Regards,
Júlio Branco

Dear Members,


I ask all excuse goes my previous information. I was induced in mistake by the fact of my manual of tubes to incorrect be. I won't usually check the technical dates of to manual when this it informs us that equivalence direct exists, in fact, to present it date, I have been following the instructions of the manuals and I have always been having success in my work. Then the reason goes the which I don't have the habit of checking the manuals I or in correct the. Inclusively to removes you doubt if he had or in the tube averaged EL33 changed goes the 6V6, the in the manual he felt this information, I made the experience given that had available the tube 6V6, the radio worked, what concluded that EL33 was damaged. I removed to 6V6, I acquired an EL33, being like this with the concluded work and without noticing the mistake that was to commit. I already analysed the tube 6V6 and it is 100 percent, it was not damaged.


A thank you very much goes all of the information that gave me on the tubes EL33, 6M6 and 6V6, once again it is confirmed that this forum is very important, and where us been always to learn.


Best Regards

Júlio Branco

Ernst Erb

Dear Julio
Nevermind. But it is essential that we also keep record of the faults in publications since we want to achieve a "reference work" here. We are far from that but on a way to it.

I kindly ask you to take this sheet you have shown to us, cross the V so taht it is still well visible and write over it M. Then scan it again and load it up with a text explaining in which book you found it and on which page.

Please do this in your first post by editing - on both entries (tubes). Then everybody has learnt something and a newcomer will not do the same but recognise that that book is wrong. You will rarely ind a book where everything is correct. It is the big gain for us that we can always improve our data to the best - but we will have to take notice of reasons and references, proofs etc.

Ernst Erb
  6 Dear Júlio
Please read my post carefully:
We should show by your picture that the sheet you have shown is wrong.
Only by that somebody can immediately see the wrong part in that book.
Lars-G. Lundelin
  7 Dear tube friends! At least the following tube-book has wrong information about the relation between EL33 and 6V6. This book is from 1956. With kind regards Lars-G


Júlio Branco

I'm sorry, Hernst


Lately I have been walking with a lot of work, reason for the which I didn't put in the post that suggested to do.


Here it is going the alert and so that all of the members of Rmorg, and not only, for everyone that visits this grandiose site to be possessors of this book they make the respective correction.




Best Regards

Júlio Branco

End of forum contributions about this tube

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