On 11/30/2020 2:16 PM, jimlux wrote: > Hmm, if you were to use exactly a wavelength (or multiple) of the 75 ohm > cable, would the wattmeter approach work? Yes, but at any multiple of half wavelength, and the excess attenuation due to mismatch would be minimal. But the measurement is only valid at those multiples. 73, Jim K9YC