The G types were first.? These are the large "semi-pear-shape" common to the pre-octal base tubes.? GT or "glass tubular"? were next but I don't have a date.? ThenRCA.RC-14 handbook, dated 1940, has all three.? I am not sure metal tubes were in short supply during the war, the shells were steel and it was.mostly copper and its alloys and aluminum that were statigic materials.? GT tubes and the similar local tubes were certainly made before the war. I don't know why Hallicrafters used G tubes.
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-------- Original message --------
From: Jacques_VE2JFE <jacques.f@...>
Date: 11/14/22 1:43 PM (GMT-08:00)
Subject: Re: [HallicraftersRadios] Need 2 Tube Shields for SX-17
Hi Richard,
?
The metal envelope tubes in 1935, (by RCA) right.
The ¡°G¡± (glass) variants came during WWII because they were less expensive to produce than the full metal shell ones.
The GT variants came at the end of the war and in the following ¡®50s.
?
73, Jacques, VE2JFE in Montreal
