Audio Control Unit
The Palomar Products Audio Control Unit (ACU) provides access to radio and intercommunication channels within a limited amount of panel space. This unit permits access of up to 30 radio and/or intercom channels assignable to the panel pushbuttons.

Panel operation is very user friendly. The receive audio is selected via simple pushbutton keys. The receive volume levels are preset to a nominal value by the communications plan resident in the Communications Control Unit (CCU), and can be individually attenuated from 0 to 20dB at the ACU with momentary pushbuttons. A master volume control provides an additional 30dB attenuation to the composite audio baseline. Pulling out the master volume control knob activates transmissions on the emergency Override (CALL) intercom net.

The unit displayed on this page has been configured for the flight engineer and observer positions of a P-3. It allows each user to communicate over four intercom nets and to monitor radio channels.

The unit can also be used in other applications where transmissions on radios is needed and panel space is at a premium. Channel buttons can be used to select radio channels for receive or transmit. The LEDs over each button can indicate radio, receiver, and transmitter selection as well as receiver and transmitter activity.

The selector keys use filmstrip technology, which allows button legends to be changed quickly and inexpensively when upgrading systems.