This Honda EM500 500 Watt AC generator belonged to my Father-in-law (sk) who used it when camping.
It is early 1980's vintage. I don't know how long they were in production but I believe the later EM500's used circuit breakers for over current protection unlike this one that uses fuses.
This generator had not been running for about 15 years and would not start when I got it. The problem was that the carburetor was varnished up due to old evaporated gas. The clue was that with the tank full of gas and the engine switch in the ON position none would drained out of the carburetor with the carburetor bowl drain valve opened. I removed the carburetor, took it apart and cleaned out the jets with throttle body cleaner. I did not have any carburetor cleaner. Fine sand paper was used to remove the varnish from the bowl. There was nothing else wrong with it but I did go through the regular maintenance routine as outlined in the User Manual. The User Manual is available free on the Internet.
Aside from the 120 VAC output the generator has a 12 VDC output to be used to charge automotive batteries. The output is unfiltered and the open circuit voltage is high so you would not want to power any of your radios from this source. It could be disastrous.
For a 120 VAC test, I used it to power the VE6KQ UHF repeater during one of our usual Sunday morning EchoLink skeds. It worked fine.
When the generator first came out there did not appear to be anything similar that was produced by any other manufacture. Although low power it was quite small, quiet and under normal conditions it usually started on the first pull. When I worked for the big "M" (not McDonald's) we had the 600 Watt version of it (EM600) that looked very similar. It was almost ideal for our needs. We very often used it on 2-way radio mountain top sites that were not equipped with AC power. The generator had enough power to run the required test equipment, inspection light and soldering iron at the same time. Because of it's size it easily fit in the helicopter's storage compartment. One thing it could not do was power an electric heater which very often would have been nice to have in the Canadian Rockies even in the summer. One other thing, it did not start well above 8000 feet AMSL but we always managed to get it going.
Since the generator is small in size and fairly quiet it may be of most interest to campers and since it is a Honda it should be quite reliable.