[TowerTalk] copper tank coils

[Jim Lux]

Tank coils and inductors are very different from antenna losses - In the former, you typically have larger current - A Q of 10 implies that there is 10 times as much power circulating in the LC as there is flowing “through”.   And there’s not much other loss, so the inductor loss dominates.

In an antenna, you have the radiation resistance (72 ohms for a resonant dipole) plus the loss resistance (a few ohms), so  the total power being lost is smaller - 10% if it were 7 ohms, which is huge.  And it’s spread out over many feet, so you don’t see it warming.
Where antenna resistance can really bite you is when you have a “physically small” antenna (magnetic loop, anyone?) and the radiation resistance is small (because of small physical size) so the loss resistance is big compared to Rrad, so you can get big percentage losses. 


On Sat, 30 Sep 2023 14:00:25 -0400, Ken WA8JXM <wa8jxm at gmail.com> wrote:

I expect results would be frequency dependent since the skin effect is
frequency related AFAIK.

I have some war surplus rotary inductors made with solid silver wire.
You can add that to your list also :-)

Ken WA8JXM

On Sat, Sep 30, 2023 at 1:45 PM Mark, K5AM  wrote:

> > Jim wrote:
> > I have wound identical coils using silver plated copper,
> > copper, and also 304 SS. The aluminum coils ran hot.
> > The SS coils ran stupid hot.
>
> Interesting!
> It would also be great to see data comparing:
> silver plated copper
> copper
> oxidized copper
>
> 73,
>
> Mark, K5AM
>
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