1937-1947. Founded by Dickerson Brothers in 1937, lap steels and small amps.  Also made amps for Oahu and Gourley Brands. 1947 changed ownership and renamed Magna Electronics (Magnatone).  [Source: Vintage Guitar Magazine Price Guide ]

 

 

 

Image ebay: Plate on back reads:

FATORS MFG. CO.

DICKERSON

3998 SO. VERMONT AVE.

LOS ANGELES 37, CALIF.

110-120 V. AC 50-60 CYC.

Dickerson combo amplifier