Shown here, on the cover of Radio News for July 1938, is Annette King, a radio personality with NBC Chicago. She appeared on programs including Club Matinee.

Of note here, she is speaking into the network’s “Beer Mug,” a portable transmitter designed for use in remotes. The crystal controlled transmitter operated on 30-41 MHz, and its 200 mW output was said to have a range of up to a mile. Batteries would last for up to ten hours, and the transmitter met all of the strict FCC requirements.

It contained an automatic modulation control which was frequently referred to as a “built-in studio engineer.” The original version weighed 13 pounds, but the one shown here was only 7 pounds. It was standard equipment at all NBC offices.