"Avery Fineman" wrote in message
...
It's not necessary to go back to just a few years after the first
audion. :-)

The Galvin/Motorola SCR-300/BC-1000 used 7-pin glass base
"miniature" tubes, battery type filaments, and was 40 to 48 MHz.
Tube types were 3A4, 1T4, 1R5 in the VHF range.

My Feb. 1942 "FM" magazine has an ad from REL selling FM mobiles for police
use. I assume the ad was bought in 1941.

A young engineer who worked for my father at the US Patent Office had one of
the MW (AM broadcast) RCA "camera-case" radios about 1940. It was based on
the tubes mentioned above. Size was about 2x4x8 inches. Most of the space
was taken up by the batteries. The A (filament) batteries lasted about 3
hours.

I estimate the date since this fellow went on active duty with the Navy
_before_ Pearl Harbor. In fact, he phoned my father with details of the
losses at Pearl the next day (Monday, Dec 8, 1941). Those details were kept
VERY secret for at least 2 or 3 years. My father kept the secret, and I
think complained to the Navy about the security breach. Apparently nothing
happened to the fellow who spilt the beans.