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Information - Help 
ID = 917
Brand: Common type Europe tube/semicond.
Tube type:  Vacuum Pentode   RF/IF-Stage 
Identical to UF42 = Z142
Similar Tubes
Heater different:
First year 1950 Tube leaflet collection E.Erb Analysis by original leaflets
First Source (s)
Dec.1950 : -- Original-techn. papers.

Base Rimlock base B8A
Filament Vf 21 Volts / If 0.1 Ampere / Indirect / Specified current AC/DC ~ = (Series working)
Tube prices 3 Tube prices (visible for members only)

UF42: Courtesy Bureau Belper (De Muiderkring, Bussum), Scan Frank Philipse
Karel De Reus †

uf42_so.png UF42: rtt
Anonymous 10 Collector

Just Qvigstad
UF42: Funkschau Röhrendokumente
Anonymous 10 Collector

More ...
Usage in Models 1= 1948? ; 1= 1949? ; 3= 1949 ; 2= 1950?? ; 3= 1950? ; 22= 1950 ; 2= 1951? ; 41= 1951 ; 1= 1952?? ; 4= 1952? ; 8= 1952 ; 2= 1953?? ; 3= 1953? ; 1= 1953 ; 2= 1954?? ; 1= 1954? ; 3= 1954 ; 2= 1955?? ; 1= 1955? ; 1= 1955 ; 1= 1956? ; 1= 9999?? ; 1= 9999

Quantity of Models at with this tube (valve, valves, valvola, valvole, válvula, lampe):107

Collection of



Forum contributions about this tube
Threads: 1 | Posts: 5
Hits: 2198     Replies: 4
UF42 release date
Pieter Hooijmans

It is stated that the UF42  was only released in 1950. This is not correct.

This tube came available early 1948, at least for internal development within Philips. There are circuit diagrams from July 1948 (for a 567-line television design) using the UF42, while the TF384A television designed early 1948 used the UF42 too (the 8 in the name indicates it being a 1948-released design).  The EF42 Rimlock valve was publicly announced in a Philips Electronic Application Bulletin of December 1948, where it is stated that the U-version were alrady released earlier.

The UF42 was used in Philips television receivers from 1948 and 1949: the TF384A, TF390A, TF402A and TF502A for the French market, the 385U, 485U, 683U and 492U for the UK market.

Mark Hippenstiel

Speaking for the French market, the following observations from literature can be made:

  • In December 1947, the "official" Miniwatt series of Television Tubes comprised of
    • MW22-5 and MW31-6
    • EE50
    • EF51
    • EA50
    • EC50
    • EL39
    • AZ50
    • and rectifiers 1875 and 1877
  • In February 1948, at the Salon de la Pièce Détachée, the Rimlock base was introduced with the series (non-standard designations used by Mazda)
    • UCH41 = CF141
    • UF41 = HF121
    • UAF41 = D121
    • UL41 = BF451
    • UY41 = V311
    • UY41 = V312
  • First advertisements with above series appear around September 1948
  • In November 1948 first advertisement of an E series
    • ECH41, EAF41, EF41, AZ41, EL41
  • In January 1949 advertisement of E series with additionally
    • GZ40, ECC40, EF42

Obviously, the picture is not complete. I didn't have time to read the stack of magazines in detail to find the official announcements of new tubes except for the Feb 1948 one.

Best regards

Ernst Erb

Dear Pieter
Thank you for addressing this. Well, France was a test market for new tubes for Philips at that time. So locally you might be right and it would be fine if you could load up such dated material.

The "dating for certainty" is only done by me, since the whole system depends on such date to tell us if a model has been proposed for a too early model.

We might to have some compromises for exception - this depending on the material you find. There are also some experimental sets and some very limited numbers for a test market. We have to consider dates for the general public and markets.

We have also to consider that my collection of primary source information from Philips was and is limited for tubes which have not been in use in big quantity at the time of presentation to the market. Therefore the tendency is that we sometimes show a too late date - but never a too early. Please send me copies to the address below (mail to author) for tubes which you would like to see an earlier date for. This would be a great help.

Is it possible for you to add the model TF502A and to look for the models for the UK market relating technical papers and/or schematics and the right yeasrs (if possible from-to)? We also miss the 623U and 492U.

Pieter Hooijmans

Dear Ernst,

My findings are based on a detailed analysis of the early TV development within Philips. See my story here. (I will in due time also upload this story to Radiomuseum, but that will take quite some effort).

My main point is that most of the valves were available for internal product development well before public launch. This was especially true for television valves, where the Philips set designers wanted to keep the new features or performance of valves confidential until the set was publicly launched. So often valve announcement and set announcement coincided. This was especially true in the 1948-1951 period, with valves like UF42, EF42, EB91, EQ40/80 and maybe a few more.

In the coming time I'll indeed plan to update the missing sets to the system.

Cheers, Pieter

Ernst Erb

Dear Pieter
Thank you for your kind answers.
You addressed something very important: We want only to show the start of the "big series", which is often not the publishing date. Normally a tube designer sends some tubes to the best clients including some rough schematics how the tube type should operate and under which conditions.

Then the manufacturer builds its own circuits (to have its own goodies if possible and depending on the model pricing etc.). If it works fine they build a handmade chassis and do an original wiring - also to find the best "zero-zones" ("earthings") for higher frequencies like FM and higher. If that all works fine comes a chassis which has all the details to create the tools for the big machines to do those complicate chassis - when it works fine including all shielding etc.

The process of creating all the tools for the "metal working machinges" like presses, cuttings etc. take quite some time and money (at those times!). This is only a fraction of what a manufacturer has to do before launching a new model ... 

So also the tube manufacturers have their time to set up mass production. Normally the difference is one year, some times more. If it is quite a new or demanding tube, the test market comes in place.

Now we have to do a compromise where we find a test market with quantities by perhaps showing the data for the real whole market, telling in the notes the details - with the disadvantage to have models with the automatic note - but hopefully compensated with a note in that model page. Or "the other way round" - where we have the loss of our good automatic detecting system!

Can you please take out the outgoing link below (which did not function anyway), since we only allow Wikipedia as outgoing link? But you may write your web page without the www and without the point so that somebody interested can reach it - since you do quite a good work also here. :-)

End of forum contributions about this tube

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