On Mon, 7 May 2007 23:03:28 +0200, "Antonio Vernucci"
wrote:

Differently from all common wattmeters, the Struthers meter has a perfectly
linear scale. How could they achieve that?

Hi Tony,

Non-linear magnetic field.

On QST magazine (May 1996, pag. 77) K3BRS states that replacing the diode with a
different type would cause the initial part of the scale to become very
inaccurate.

The difference between silicon and germanium, perhaps.

Does anyone know of special diodes resulting in a linear wattmeter scale?

No.

73's
Richard Clark, KB7QHC