Please click your language flag. Bitte Sprachflagge klicken.


Information - Help 
ID = 27490
Tube type:  Half-Wave Mercury-Vapor Rectifier 
Identical to RG1,5/250

Base Europe 4-Pin B4 (Eu A, E, 4A) 1914 Top contact with a cap.
Filament Vf 4 Volts
Dimensions (WHD)
incl. pins / tip
45 x 115 x mm / 1.77 x 4.53 x inch
Information source -- Collector info (Sammler)   
- - -   
- - -
- - -
RG1,5/250: Sammlung KHB
Karl - Heinz Bossan


from Just Qvigstad

Forum contributions about this tube
Threads: 1 | Posts: 9
Hits: 1898     Replies: 8
und wieder eine 'unbekannte' Röhre: RG1,5/250
Mark Hippenstiel

Hallo zusammnen,

schon wieder ist mir eine nicht weiter bekannte Röhre in die Hand gefallen: eine Philips RG1,5/250.

Kann jemand etwas mehr über das Rohr sagen? Es ist vermutlich ein Quecksilbergleichrichter, aber leider habe ich keinerlei Daten.

Die Röhre ist zusätzlich noch CV1072LSK gestempelt. Sockel B4, mit Kappe.


Vielen Dank für eure Unterstützung!

Mark Hippenstiel

Roy Johnson

Dear Mr Hippenstiel,

This was manufactured in 1961 and is a mecury vapour rectifier.

Heater/Filament is 4V at 3A.

1.5 kV peak at 0.25A mean.

Bitte entschuldigen das Ich auf english die Daten schreibe.

Herzliche Gruesse,



Mark Hippenstiel

Dear Roy,

thanks for the information. Looking up the cross reference, we find the CV1072 is also equivalent to GU50, AU6 and VU72 and (per RMorg) G4150.

The 'National Valve Museum' links the type to RG1-240.

I am particularly interested in the fact that information is scarce about this type and the additional 'LSK' marking which clearly is part of the designation.


Daniel Consales

Hallo Herr Hippenstiel,

im "CV Register of Electronic Valves, 1963" findet man folgende Zuordnungen:

CV1072 = GU50 / RG1-240A / MU4250 / CV1626 / CV2738

CV1626 = zusätzlich RG1-240 (ohne "A")

CV2738 = RG1-240

Für die RG1-250 findet man: CV3667 !

CV3667 = RG1-250 / GU1 / CV1262

CV1262 = GU1 / RG1-250  - hier schließt sich endlich der Kreis :-)

Leider auch hier kein Hinweis auf die Bedeutung von "LSK"


Gruß Daniel Consales

Nachtrag Daten der CV1262:

Vh = 4V
Ih = 3A
VRMS = 1000V
Ia = 250 mA
Base = B4 :

1 = A
2 = frei
3 = f/K
4 = f/K

Da Sie schrieben: "B4 mit Kappe" passt das also nicht ganz, daher hier noch die Pinbelegung der CV1072:

1 = frei
2 = frei
3 = f/K
4 = f/K
Kappe = A

Roy Johnson

Dear Mark,

You are correct there is little information as it was in limited production for a short time being largely replaced by the RG1/240A.

In 1962 and possibly earlier it was only manufacured to special order and not held as a stock item.

Incidentally the "A" added indicated a 4-pin base as against the ES base.

There is a great deal of misunderstanding about CV designations.

The CV designation was devised as a common UK services series replacing the separate army, navy and air-force designations.   The CV red book "Electronic Valve Specifications" published by the Ministry of Supply sets out the types, testing and acceptance procedures.

Valves that met the particular specification could then be labelled with the CV identification.  Civilian (commercial) valves which had been in use and found satisfactory were given a CV designation and hence can be regarded as an "equivalent" to the CV type.   Where a specification was issued - often based on an existing type or submitted prototype, manufacturers could submit a batch of valves for testing with a view to approval as that CV type.

If the submitted valve has an equal, or better performance than the specification it was accepted. For a rectifier, filamen/heater voltage and current conformity, anode voltage and current at least equal to to the specification and performance during life were all criteria in addition to the physical dimensions.

The CV register of valves lists "prototypes and possible substitutes" - this is often misinterpreted as equivalents.  Usually, but not always the first-named is the prototype. In this case it was the GU50 with the other types that Mr Consales correctly names. 

Because the listed types are "possible substitutes" NOT equivalents that would explain the apparent conflicts.

Mullard/Philips offered the RG1-240A for the CV1072, CV1626 and CV2738 specifications. The RG1-240 has a maximum mean current of 250mA.  I have not investigated, but presumably it started life with a 240mA rating subsequently up-rated to 250mA.   That then presumably rendered the RG1-250 obsolete and hence the rarity.

The RG1.5/250 (should there be "A" after that?  Perhaps Philips differed from Mullard?) would seem to be a special batch.  I have seen letters added to a CV number but cannot explain the "L" other than as a batch -or  if it were subcontracted to CSF?   Are there any etched markings on the glass or the base? 

Kind regards to everyone,


Ernst Erb

Dear Roy

I'm delighted about your outlines for CV designations. Unfortunately this is in "Talk" and will therefore more or less disapear. All tube lovers here - and gusts (who can not see "Talk") would be delighted to see your text as an indipendant article.

The board would be "Military valves" within "Valves/tubes".

On top of this would it be very good if this article would be linked in the text (for English) on each CV-valve here. With this our present system would then not necessarily lead to false assumptions according to "identical tubes". Since in the literature you can often see such equivalents but only few are real equivalents we will always have the problem of uncertainity - if not explained like for instance:

CV1234: prototype XY123 and XY234 - see here for the others.

CV1234 would be the CV valve of the particular page (as a repetition), XY... would be the prototypes which we can consider to be equal and "see here for others" would be a link to your text. If we don't know the prototype(s) we would only point to your text, perhaps with "Be careful if you choose for an equivalent ..."

Since I know that you are a real valve connoiceur and a member since October 2006 who has prooven to be an active member I would very much like that you accept a post as valve admin. You would not have any obligation but all the rights to enter new valves/tubes and to add or change data, text etc. You could focus on British valves if you like but you don't have to.

I just had a look via tube search with "starts with" CV but we have already too many for the system timeout - but with CV1 we get 450 types - not all of them being "our" CVs naturally. CV2 brings 147, CV3 = 131, CV4 = 18 and CV- is empty. Our military CV will only be a fraction ... (yet;-) I'm sure that we list also only a fraction of the British radio valves :-(
But don't think all this would be your duty ! We have at least two members as tube admins who have begun without knowledge and have still done quite a lot for the tube/valve pages. I'm sure they would also help fulfill your wishes in respect of bulk work.

Roy Johnson

Dear Ernst,

I am honoured by your comments and suggestion.   I would be very happy to help in this way as I had started to look at the CV list and requested some additions to Otmar, but am very conscious of the additional work imposed on admins.  If I can "short-circuit" that process it would be useful for everyone!

I have often to point out the reality of CV designation and was considering an article about the origins of VR,10E, NT and CV designations as I am often asked about this and it is a common mistake to consider a CV designated valve as a type.   It often is, but not necessarily as you will know! 

There are many problems with valve types and I have just up-loaded some pictures of the RG1-240 and 240A.  This shows the variant that the "A" initially was not added to a 4-pin and also supports my theory that initially the 240 was a lower current device as the cathode structure was modified in the later type. 

Perhaps some of the above discussion should be moved to the RG1-240 as it is specific to Mark's initial posting? 

Please let me know I can help in any way and the details needed.

Following our earlier exchange I have been looking at the translations and am alo compiling a list of a few suggestions that I have to clarify for the english speaker.   I thought that it would be best to get broad experience of the museum and not put suggestions "piecemeal" as that just wastes time. 

With kind regards,


Mark Hippenstiel

Dear Roy,

your remarks regarding the CV register are very interesting and informative, thanks for providing these insights.

The envelope is quite opaque, so I cannot identify the system, but it seems to have the cathode shielded from the anode plate. It's difficult to see.

There is an etched marking reading J36 just below the designation. The print is in good condition, a fact that, together with the block paragraph print with the PHILIPS logo lettering, makes a missing 'A' quite improbable.

As soon as the tube has been created, I will ask for this thread to be moved there.

Best regards,

Roy Johnson

Dear Mark,

Thank you for the update.

Following our initial exchange I went in search of my valves!  As you will see from the above my early Mullard has a 4 pin base without the "A".  The J36 code does not seem to tie in with any information that I have - "J" COULD indicate Mullard (Tungsram) but this seems dubious.  Many codes do not seem to follow any known pattern at that time!

If you want to look inside, put 4V on the heater and it will magically clear the mercury deposited on the walls!  It takes a minute for the glass walls to evaporate the mercury.   The heater is below a slot in the main cathode and electrically connected at one end.  The valve must be warmed up before applying the "juice" (HT) - as in some diesel engines!

Best regards,


End of forum contributions about this tube

You reach this tube or valve page from a search after clicking the "tubes" tab or by clicking a tube on a radio model page. You will find thousands of tubes or valves with interesting links. You even can look up radio models with a certain tube line up. [rmxtube-en]