> I believe many old 3-500Zs are in SB-220s, which are designed to this
> standard. No?
Inrush related failures are pretty rare Pete, especially if you do not
oversize components in the filament.
Buzz WA4GPM, a former senior engineer at Salt Lake, told me they strapped
3-500Z's filaments to very large filament transformers and cycled them off
and on hundreds of times with recording any failures.
Damage is a time and amount problem, if there is any damage. The peak inrush
in a SB220 isn't much over twice the rated current, so it wouldn't be a
problem anyway.
If you look back, you'll find a wave of "it must have been inrush" worries
in the 70's caused by one or two articles telling everyone how inrush was
killing reliability in the SB220. Naturally the articles and resulting
hysteria and series of modifications were unfounded.
73 Tom
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