Fragment of correspondence off the list.... On the spacing of two tone tests... You are absolutely correct... there is not a foreign product that I am aware of that can run with the Omni line regarding imd on real world interference at spacings of 2 to 5 kc....the magazines testing their advertisers products at 20kc and 50kc is questionable at best, duplicitous at worst, and irrelevant to the real world... Denny