There's nothing wrong with trying to achieve a better IMD spec. than
the minimally acceptable ham radio level. It is fine and laudable to
have a goal that is consistent with professional standards. That's
how you get better in this hobby.
>I took apart a hallicrafters TV to show to a friend (assuming the issue would
>exist), and there it was around the high voltage rectifier tube, fine dust,
>with some blackened areas due to corona.
Warning regarding vintage TV sets with vacuum or gas rectifiers: The
h.v. for the CRT in these sets was usually high enough (10 KV or more)
to cause x-rays to be generated at the rectifiers. Shielding is
necessary. When TV was new, TV repair men were exposed to high
amounts of ionizing radiation because they were close to operating
sets. Consumers were usually far enough away to not be injured. You
had to be within 3 feet or so of the set to be in danger. At some
point the industry put in shielding but I don't know what year that
was. What happens: With any tube that has ~10 KV or more anode
voltage, the electron attraction is so high, they strike the anode
with enough force to generate x-rays. Most ham RF amplifiers do not
have such high plate voltage and are safe. TV sets are a different
matter but you have to have an old set with tubes to be concerned.
73
Rob
K5UJ
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