I'm really kind of baffled what the guy means my 18 db signal to noise.
It's kind of meaningless without knowing how it is measured. Noise is
propertional to the square root of the bandwidth, so you need to know
what filter is being used.

I'm not sure you would use a noise figure meter. Seems to me you would
want the SNR measured from RF input to speaker output because that is
how you use the radio.

I may do this measure some day for yucks, but it will be a bit of work.
I'd have to fire up the old HP334A just to measure the THD of my RF
generator, not that I ever used the box in that mode.