Topband: Stainless Steel for coil taps.

[Mail 10]

Rob, are you implying that I shouldn't use a steel lattice tower to 
conduct RF as a radiator?

For coil taps, I like to solder.

Luke VK3HJ

On 16/11/2020 10:05 pm, Rob Atkinson wrote:
> We all learn this sooner or later:  Don't use ferrous metals to
> conduct RF.   If a metal fails the magnet test, it's out.  Every time
> I get some item of homebrew or something that's had a previous owner,
> (transmitter or matching network) I go through with a magnet and see
> if a previous owner or builder used steel around RF stages or matching
> networks.   Some steel alloys may be better than others but it's
> impossible to tell, so out they go.  Brass, copper, aluminum, silver,
> nickel all okay.   EF Johnson and perhaps others used steel nuts and
> bolts that were plated with nickel.  That's okay as RF current has the
> skin effect.
>
> What's wrong with ferrous metals?  They don't conduct as well but more
> important, at the microscopic level, they vibrate at the RF frequency.
> This does two things:  Generate heat, and slowly loosen clamp, as in
> the case of a nut, bolt and washer for example.
>
> Rob
> K5UJ
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