1959 Zenith Royal 500D, chassis series 8AT40
Coat pocket radio, nylon cabinet
5 3/4 x 3 1/2 x 1 1/2 inches / 146 x 89 x 38 mm
Eight transistors (Zenith round cans)
Superheterodyne circuit, vernier tuning
Four 1.5-volt AA cells
Manufactured by Zenith Radio Corp.; Chicago, Illinois
An additional RF amplifier transistor and a huge cosmetic improvement to the cabinet face just by modifying the speaker grille made this the nicest version of the round-grill Zenith 500 series. The unit shown here has a 8AT40Z2 chassis.
And I can't help saying here that this 500D holds a special place in my heart — it was the first transistor radio that I bought as a radio collector: I found it at a yard sale a few miles from my house in June, 1988 for $3.50 — I actually walked away from it ($3.50 for a transistor radio? — that was outrageous at the time!) and then I came back several hours later and bought it.
It played well, and long after I had collected many other transistor radios, this 500D continued to be the radio I actually used, mostly to listen to Red Sox day games in my back yard. After I moved to Europe in 2004, I used it for MW DXing and logged stations from all over Europe and North Africa. I'm sure I could have done even better with my 500H, but this 500D was "my radio"....