I bought two of these a few years ago but never got around to using them. The were working per the old owner but being sold as is as things like caps do go bad over time. There is a lot of info on the WEB. This is a 1KW keydown forever amp so would do RTTY, AM or the digital modes with no problem. There was not a lot of these made. The little brother the 2KL had a lot more build and sold probably because the 4KL was a very expensive amp with build in PS and antenna tuner . Amp will track the band of a ICOM radio via the interface.