Original EF50?

Dear members,
                           I wonder if anyone has more information on
what I believe was the original version of the EF50 vhf pentode,
which I'm told had a metallised coating (not the aluminium can
of later versions) and L-shaped pins, so that the valve had to be
pushed in and twisted to lock? (1939?)
    I'm told there were problems with side pressure on the pins
cracking the glass, but I wonder how many were produced?
    A good photograph or information on the whereabouts of one
would be most welcome! 
 
Regards from
                     John.

To thank the Author because you find the post helpful or well done.

Hello John,

unfortunately I have no additional information as is written in the book "70 Years of Radio Tubes and Valves" v. John W. Stokes, 1982.

The EF50 was far less common here in continental Europe as it was in the UK, so the chance is even smaller to find more information here, - with the exception if someone has intensive access to the Philips archives.

Best Regards

Jacob

To thank the Author because you find the post helpful or well done.

This is familiar but I cannot find anything about it. I wonder if I saw a drawing or was told - though I would generally keep such information. I am sure I have seen more than the short reference in Stokes.

To thank the Author because you find the post helpful or well done.

I have the ref via Rod Burman in the UK: Wireless World Feb 16 1939, page 155 to 156. We have this in our works library and it has a drawing of an all glass valve with the hooked pins. I can send you a scan if you like.

To thank the Author because you find the post helpful or well done.

Thank you for  the replies from Jacob and Jeremy; like you,
Jeremy, I either have or have seen the drawing you refer to -
(a bit crude if I remember right; but where? - I didn't see it in 
W.W.), and I'm thinking it may have been in "Radio Bygones",
"Short Wave Magazine" or similar. (probably copied from W.W.?)
    What I'd really like to see is a good photo of valve and base,-
but then, I always was an optimist!!! 
   
 If the article in W.W. has a fair bit of informative text, then I
would be grateful for a scan, but only as and when you can find
the time; and if I learn any more I'll keep you posted.
  It seems the valve would have been developed by Philips, but
a lot of Philips archiveal material seems hard to find, at least to
me; maybe I ought to try and learn Dutch?

Thanks and regards,
                                John.
P.S. - I note that Jacob has now requested a scan for the archives,
 so that would be o.k. for me to examine when you do, thanks, J.T.

To thank the Author because you find the post helpful or well done.

Hello Jeremy,

I am interested too to have a scan about this document. We can put it to the EF50 page here in our tubes / valves section as additional information.

Best Regards

Jacob

To thank the Author because you find the post helpful or well done.

John - I bet it is in Radiobygones - that's the one place I have not looked. I can confirm the WW article has a pic of the valve, though the scan came out a bit speckled, and a line drawing of the valve and base details showing the hooked pins. There is a fair amount of text including, at the end, the bit about inserting the valve and giving it a twist. However the article is about the 'new' valve and thus does not indicate any of the issues that were later found. I wonder if there is a later WW article saying why the EF50 was changed to what it is today.

I have put the PDF here for now (2.1Mb):
http://www1.leeds.ac.uk/~jeremy/all-glass-valves.pdf

Jeremy

To thank the Author because you find the post helpful or well done.

Jeremy,

 

Thanks for the document - is it possible send it to me as PNG or GIF file, since I can't processing PDF files ?

Thanks in advance,
Jacob

To thank the Author because you find the post helpful or well done.

Jeremy,
             many thanks for finding the information regarding the
first version of the B9G valve type construction, especially the 
picture of the first EF50, first sighting I've had!
   I hope you manage to let Jacob have the file in a format he can
utilise; I don't think you can put pdf. files in Irfanview - I tried,
but all I could do was print from Adobe, then scan again and put
that in Irfanview - my results, at least, weren't good!
  I'm wondering now if any of the other B9G valves took the same
form, with hooked pins?!

Regards,
               John.

To thank the Author because you find the post helpful or well done.

Hello Jeremy,

it's no longer necessary to send me a converted file - our friend Otmar Jung did this job in the mean time.

Now the article for the EF50 is finished and uploaded.

Regards,
Jacob

To thank the Author because you find the post helpful or well done.

 

Dear Jacob,
thank you for your help; here is a little more
information regarding the EF50 and it's history - these two
letters are reproduced from "Radio Bygones" magazine,
with kind permission of the editor (Wimborne Publishing Ltd.) 
<http://www.radiobygones.co.uk>
Apparently there was a question as to whether the EF50 was
ever used in German WW2 military equipment.
One of the writers, Mr. A.O. Bauer, has a wealth of German
technical information at -

 http://www.xs4all.nl/~aobauer/

(Web address corrected, - J.T.)


I'm still learning how to use the facilities of RMorg, and I'm
grateful to Jacob Roschy, also Otmar Jung for guidance!
I would be grateful for any information on the early use of
the EF50.

Best regards, John Turrill.

 

Attachments:

• GeEF50useLf (78 KB)
• German EF50 use (52 KB)

To thank the Author because you find the post helpful or well done.