Sanyo 6C-3
The back cover reads "SANYO ELECTRIC CO., LTD. OSAKA JAPAN"
On the side you can see the two earphone jacks and, between them, the "antenna" and "external battery" jacks. The external battery jack and lower earphone jack were designed with the optional SX-3 external speaker box in mind. The SX-3 "Extra Speaker" not only featured a 6" x 4" elliptical speaker for home use, but also functioned as an alternate power source for the radio when its power cable was plugged into the "external battery" jack on the radio.