• Persoft, which made our original wireless bridges, left the wireless business (mainly due to regulatory issues) and then was bought

 
• Current FCC rules are inflexible; require every combination of equipment to be certified even if calculations can determine conformance. Also require "unusual" connectors, making repairs difficult

 
• We had to track down Persoft's original suppliers, and buy up used equipment from other customers, to keep the network maintainable and legal
   
• Most outdoor Wi-Fi installations are uncertified (mixing and matching of antennas, addition of amplifiers are common)

 
• Same problem occurred in PC industry, and was solved by changing approach to certification

Lesson #6: For outdoor installations (at least), licensed or certified installers (who know how to calculate EIRP, etc.) should be used to maintain conformance rather than certification of every combination. This approach also helps lightning safety, ensures proper grounding, etc.