In making furthur experiments I am obviously re-inventing the wheel but no harm done. I tried the 4ft dish at 60 metres today.

Environmental ambience was high due to light intermittent breeze in the trees. The clock can very barely be heard ticking and only when there is a bit of favouring wind. It is right down there in the noise floor and only discerneable because I know the sound.

The small transistor radio at its lowest loudness setting was audible with all the mixer gains right up. With the environmental noise floor gained up to -12db, the radio speaker was returning about -5db at best. Direct to ear, I was not able to hear the radio beyond 8 metres.

A human male voice at normal close conversational modulation from 60 metres fares less well. Only occasional words were discernable and only because I have done a bit of HF radio listening in the past and am hearing-trained for difficult conditions. This might have been in part because I was able to decline the dish very close but not quite low enough.

The wings of a magpie flying though the sound path were deafening at those settings.