[Hallicrafters] Tube question for old-timers.

[Al Parker]

Hi Skip,
    The Bible(s) to help answer your questions would be "Tube Lore" by
Ludwell Sibley, along with a good tube manual.  IIRC, changes were made,
maybe in areas such as lead lengths to allow higher freq.s, etc.  A bit
later, the miniature tubes came in with many advances.   WW-II contributed
immensely to technology growth.  It's a fascinating subject, I wish I
could remember all I may have known.  You may get many more illuminating
responses.
    And remember, "they don't make tubes like they used to."
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info

----- Original Message ----- 
From: "Waldo Magnuson" <magnuson at mac.com>
To: <Hallicrafters at mailman.qth.net>
Cc: "Waldo Magnuson" <magnuson at mac.com>
Sent: Wednesday, March 23, 2005 6:59 PM
Subject: [Hallicrafters] Tube question for old-timers.


>     This morning, while I was waiting for my wife, I was reading "The
> Bible" (otherwise know as "Radios by hallicrafters" by Chuck Dachis)
> and noticed that the tubes used in the Hallicrafters receivers changed
> types around about 1939.  Prior to 1939 the tubes were mostly 6A7, 6C5,
> 6D6, 6F5, 6L7  and so forth.  In 1939 there was an "early" and a "late"
> model of the S-19R (according to Dachis).  In the late model a 6SK7 was
> used in place of a 6K7 and a 6SQ7 was used in place of a 6Q7.  Later
> radios used more of the 4-character tubes in place of the 3-character
> tubes.
>     My question to the old-timers is:  Were these improvements to the
> same tubes, or just an envelope change, and was there a naming scheme
> used for the changes or upgrades ("S" seems to have been used for some
> of the early transitions).
>     Thanks.
> 73,  Skip Magnuson W7WGM
>
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