On Wed, 12 Aug 2009 14:09:47 +0100, "Graham." wrote:

that doesn't follow at all. Wavelength of 2.4 GHz = 12.5cm. Size
of a water molecule = well, considerably less!

That was my mistake, I was thinking of particles rather than
wavelengths. I was thinking a microwave "particle" (photon?) was much
smaller than a water molecule. Thanks again for the reassurance, I
will save my time and money and not take it to a centre.