General Electric H-501X, 1940
Tube complement: 12A8GT mixer/oscillator, 12SK7 IF, 12SQ7 detector, 35L6GT audio output, 35Z5GT rectifier.
Approximately 8-3/4 inches / 222 mm wide.
The suffix X in the model number stands for Onyx, and refers to the cabinet color. Nowadays we (or at least I) think of Onyx as meaning a very dark color, or black. But it also means "having bands of different colors ... translucent or milky quartz," thus describing the appearance of this Beetle plastic cabinet.
General Electric H-520, 1940
This one is of a brown Bakelite-like plastic that's very heavily mottled with different shades of brown and tan. This particular model has pushbuttons ("Feathertouch Tuning" keys) for easy favorite-station selection.
The H-520 has a beautiful molded plastic back, which encloses the loop antenna.
The "H-500" series was available in many different versions. First, G-E made 'em in three colors: oak (mottled brown), onyx (Beetle plastic), and ivory. Second, they came with and without pushbuttons. Third, they were available with and without a built-in loop antenna (the G-E "Beam-a-Scope"). Fourth, there was a UL-approved version, or a relatively unsafe one with the AC line connected directly to the chassis. The UL-approved version was probably sold only in those markets, such as Los Angeles, where local codes required it. (There were two UL-approved versions, the later of which had a 'U' suffix rather than an odd-numbered model designation.) I don't know the model numbers of versions without pushbuttons but with the built-in loop antenna.
|G-E H-500 SERIES|
|Without pushbuttons||With pushbuttons|
|Built-in loop||External wire|
|Oak||Not UL approved||H-500||H-510||H-520|
|Ivory||Not UL approved||H-500W||H-510W||H-520W|
|Onyx||Not UL approved||H-500X||H-510X||H-520X|
Here's a G-E catalog page that lists some of the model numbers from the chart above.