On Fri, 26 Jun 2009 18:19:49 +0100, Clint Sharp
wrote:

If it's not an inverter type then it has to be pure sine wave doesn't it
or am I missing something?

I don't know, that's why I asked

I'm sure only inverters have square wave outputs but I don't know
whether some generators have more noise than others or less stable
frequencies than others?