Zenith Royal 500, called "owl
eyes", was manufactured in many versions which differs in the
chassis model and in the case shape.
The
first version “A” (chassis 7XT40)
has 7 transistor, doesn’t have the printed circuit board
and it’s hand-wired; It
differs from the other versions by
the bars that extend across the volume and tuning knobs and the tuning control is direct made, the knob operates in
the variable capacitor shaft.
The B version (chassis 7ZT40),
made in 1957, has the printed circuit board and a vernier tuning
capacitor.
In 1958/59 was manufactured the D
version (chassis 8AT40)
which has an extra transistor added to improve reception.
In 1962 Royal 500 was entirely restyled
(H version) later manufactured E and L versions.