The 5900W has ambitioned technology for it's age (1976) with chrystal marker and dual conversion shortware receiver, the scale mechanism allows frequecy reading accuracy of approx. +-5 to 10 khcs which is absolutely ok for AM broadcast receiption. Of course it can be used for SWLs to listen to Shortwave-Hams in SSB.
After the years it often suffers from different contact problems at least at one of the numerous switches. This can be solved with a drop of Ballistol Oil. Helps also with "cracking" potentiometer regulators.