[tcdriver]

After my post last night, I decided to do a little research. It seems that the Fisher 500 came a little later about mid 1957. The 500 had a signal strength meter instead of a tuning eye tube and the dial glass marking were somewhat different.

The unit you have seems to be more closely related to the Fisher Model 70-RT which was current in 1955. The 70-RT has the same tuning eye tube with the Fisher symbol on either side just as your unit does. Whereas your Fisher has six knobs on the front the 70-RT only has five. The 70-RT was a FM-AM Tuner / preamp. The logical mate to the 70-RT would have been the Fisher Model 70-AZ a twenty-five watt basic amplifier that used 5881 output tubes.

In any case, it looks as though you have a pretty rare unit in unusually good condition.