Jim Miller wrote: >Go to http://www.r-390a.net/faq-refs.htm > >Read the "Cost Reduction Program for Radio Receivers, R390/391( )/URR Final >Progress Report, Collins Radio Company" > >This report may shed some light on the evolution from the R-390 to the R-390 >(A model). It also mentions a "B model". > Thank God THAT never made it to production. Then we'd need to rename it the "R-390-B non-A".