I was reading the bbs, and saw your question rdf doppler system. I have some 
literature from loppler systems, inc. that was stored away in my desk. The 
postmark on the letter is may 12, 1993 so at that time they were still in 
business. the address is Doppler Systems, INC.  PO Box 2780   Carefree, 
Arizona 85377.  Phone number is (602) 488-9755.  fax:(602) 488-1295.  hope 
this will help you.
73's
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