[ARC5] No Doubt Dumb Tube Question

[Richard Knoppow]

----- Original Message ----- 
From: "Robert Eleazer" <releazer at earthlink.net>
To: <arc5 at mailman.qth.net>
Sent: Monday, June 17, 2013 9:12 AM
Subject: [ARC5] No Doubt Dumb Tube Question


>I am reading some in an early 50's USAF training manual, 
>Radar Circuit Analysis, because it gives a good description 
>of vacuum tube circuit basics.  What I saw there led me to 
>dig out my Sylvania tube manual and look up some data.
>
> Last year I was rebuilding the ham-built power supply of a 
> BC-348 and was surprised to find that the transformer HV 
> went straight to the filament of the rectifier tube.  I 
> had never thought about it until I had to wire a rectifier 
> tube socket, but had assumed that such tubes (e.g., 5Y3) 
> used indirectly heated cathodes.
>
> But now I see in the Sylvania book that there are not only 
> rectifier tubes like the 5Y3 that use just a filament but 
> also those like the 5V4GA and 5AR4 that use indirectly 
> heated cathodes.  Furthermore, such tubes seem to still 
> have the filament hooked to the cathode internally.
>
> So why do some rectifier tubes have indirectly heated 
> cathodes and others do not?
>
> Thanks,
>
> Wayne
>

     I think I mentioned the tube engineering books at 
http://www.tubebooks.org   For anyone interested in a deeper 
understanding of how tubes work and how they were made this 
is a treasure.  There are lots of books there but I 
especially want to recommend the four volumes of RCA 
engineering data.  Two of these were in-house training 
textbooks for tube division employees, one from 1940 and the 
second from 1962. In addition there is a two-volume set of a 
collection of scientific and technical papers by RCA 
researchers.  These are very large files but very well 
scanned.  I strongly recommend downloading these and having 
the printed out.
     In addition to these there is a well scanned _Radiotron 
Designer's Handbook_ 4th edition, probably the most complete 
compliation of articles on all aspects of RF and audio. 
There will never again be anything like it. There are many 
other books, I think even the Henney book I cited in another 
post.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com