Ahh cbt, now I see.....yup we use that at work for learning new s/w packages like MS Word, Lotus Notes and all that cr*p.......( whatever happened to a good old pen and paper based memo ?)
4CX250's, hmm a blast from the past......remember the old Pye Vanguards and Rangers use by the police and Ambulance service...were fav's by radio hame for conversion to 2m........
Ring modulators based on diodes , yup remember them too, thing is technology is changing soooo fast, its sometimes difficult to keep up....I guess by the time I've fully mastered pics, we'll be on to something else 8)