Salt on Ice
(Sept 7 2012)
This page is a sub-page to PRECISION MEASUREMENTS OF NOISE FIGURES.

The image below shows the Linrad screen when 10 g of NaCl (ordinary table salt) was added to a ice/water mixture in which a dummy load was immersed. The volume of liquid water was 2.4 litres at the end of the experiment for a concentration of salt of 4.17 g/l.

The first time slot with S/N=33.4467 dB is just water and ice. The water as well as the ice is ordinary household water. Right at the end of the first time slot the salt was poured onto the ice and the mixture was stirred a couple of times.

The second time slot with S/N=33.4523 dBis when the temperature has stabilized. The difference 0.0056 dB is a factor of 1.0013. The NF of the LNA used in this experiment is about 0.2 dB (13 K) so the differennc corresponds to a temperature change of 0.0013 * (273+13) = 0.38 degrees.