"Antonio Vernucci" wrote in message
...
Can any one explain the rationale behind using both octal
and loctal tubes in the SX-42?

73

Tony I0JX

Some locktal tubes had quite low interelectrode
capacitance compared to their octal equvalents due to the
stem seal base with shorter leads than octals. They were
also quite rugged since they were originally intended for
automobile receivers and some had less microphonics.
Remember, locktals predated miniature tubes but had some of
the advantages of miniatures due to the method of bringing
the leads out.
Good engineering practice is to use as few variations
of parts as possible but Hallicrafters never seems to have
been concerned with it. I rather think their philosophy was
that people would use a piece of their equipment until the
new model came out. One can find a lot of advanced
technology in Hallicrafters stuff, like the use of acorn
tubes, beam switching tubes, pentode RF power tubes, etc,
but often not applied very well.


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Richard Knoppow
Los Angeles
WB6KBL