Precision Radiation Instruments Model 123 "Squealer" (ca. mid 1950s)
Although it employs the same case as the Model 107C and Model 121 Geiger counters, the Precision Radiation Instruments (PRI) Model 123, known as the “Squealer,” is not a radiation detector. It is a speaker-amplifier that serves as an external audio output for the detector that it happens to be coupled to. The standard Precision Radiation Instruments Inc. meters (e.g., the aforementioned Model 107C and Model 121) had connectors for headphones, but did not come with a built-in speaker. The Squealer gives the user the option of listening to the audio output of a PRI instrument without having to use headphones.
Dimensions: 3.75” x 4.5” x 7.5”
Controls: Volume, tone
Batteries: Two 1.5 volt "D" cells, one 45 volt, one 67.5 volt and one 1.5 volt (?) penlight batteries