The fact stainless is "magnetic" or not isn't important at radio
frequencies. Eddy currents and skin effect keep the magnetic properties out
of the picture.
If you add a solid steel slug core in a coil it reduces inductance, unless
the core is powdered into such small particles eddy currents are not an
issue.
The only effect of steel or iron is it behaves as a slightly more resistive
conductor than some other conductors.
Loss is proportional to current density, and current density is so low in a
typical HF amplifier or tuner enclosure you will NEVER be able to notice the
difference in loss between using steel or copper.
The exception is cavity type systems at very high frequencies, where
standing waves concentrate current in small physical areas. In that case,
current density can be high enough to add loss.
The same goes for bolting connections. Unless a small area has concentrated
current (either through induction or conduction), there is no effect. By not
running the current through the bolts or screws, and by using the steel
hardware to only mechanically clamp things together, there is no ill effect.
Once again, magnetic or non-magnetic doesn't matter except as it slightly
reduces skin depth.
73, Tom W8JI
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