The third generation of 500’s (Model D) was introduced in 1958. It had several minor changes to it’s appearance and like the earlier transition from handwired to printed circuits, there were variations that occured during this period.

The Zenith shield was changed to black and gold, and somewhat smaller in size. Both knobs now sported clear protective collars with reverse letters and numbers printed on them. The very first D’s produced had black letters and numbers on these collars, but that was soon changed to white for the majority of the production run.

Inside, Zenith added an additional transistor, an improved extended range speaker, and of course, improved performance. The model D was Zenith’s first pocket transistor radio to be distinguished as “Long Distance” and this was stamped lightly on the front above the speaker and just under the word Zenith. The early and mid D’s have a concave grill and later D’s have a convexed shaped grill to allow for their new speaker. Radios with this speaker also have “500D” printed on the faceplate.

The model D was offered only in black, maroon, and white (tan and pink were discontinued). Production numbers continued to increase as another 200,000 or more were made making these some of the more common of the 500’s.  However, the long distance capability and improved sound of the 8 transistor chassis make them popular for those who want an “Owl” to listen to.
Fact Sheet

Model:	Royal 500D
Colors:	Black, White, and Maroon
Year introduced:	1958
Cost New:	$75.00
Size:	5 1/2 x 3 1/4 x 1 1/2
Weight:	16.1 ounces
# of transistors:	8
Power:	4 AA batteries
Undistorted output:	100 milliwatts

Check out these Royal 500D radios.

Early black model D
Later white model D
Maroon Mid Model D
Mid Black 500D
Late Maroon Model D