mike wrote:

I believe they're all licensed from Panasonic.
When I bought mine, it seemed that all the licensees had
dried up leaving Panasonic as the only locally available units.


Found a site that said GE and Whirlpool used to license the patent, but no
longer do. Just did a quick Google patent search - there are more than one
related to the use of an inverter to control the magnetron, all held by
different companies.

IIRC patents are only good for 17 years or so. Seems like they would have
expired by now.