1.1
INTRODUCTION
This manual provides the installation and operating instructions for the Garmin GMA 340, GMA 340H and
GMA 340 Dual ADF Audio Panel. Reference to GMA 340 throughout this manual refers to all versions of the
unit. Information pertaining to the maintenance of the unit can be found in the GMA 340 Maintenance Manual,
P/N 190-00149-02. After installation of the GMA 340, FAA Form 337 must be completed by an appropriately
certificated agency to return the aircraft to service.
1.2
GENERAL DESCRIPTION
The Garmin GMA 340 Audio Panel meets the needs of aircraft owners and operators who require reliability and
versatility in the essential audio switching function. LED-illuminated push-button simplicity and intuitive panel
layout allow audio selection of both NAV and COM audio. Large, single-button activation of the COM
microphone and audio for up to three COM transceivers simplifies cockpit workload. Photocell dimming
circuitry automatically adjusts the brightness of the LEDs to a level appropriate for ambient cockpit light. A fail-
safe circuit connects the pilot's headset and microphone directly to COM1 in the event that power is interrupted
or the unit is turned off. In the event of power loss a fail-safe warning audio will be heard.
Additionally, the GMA 340 includes a six-position intercom (ICS) with electronic cabin noise de-emphasis, two
stereo music inputs, and independent pilot, copilot, and passenger volume controls. To further simplify the
cockpit workload, the intercom provides three selectable modes of isolation. One hundred percent solid state
circuitry and extensive use of surface mount technology are employed. A pilot-selectable cabin speaker output
can be used to listen to the selected aircraft radios or to broadcast PA announcements. The PA function is pilot
selectable.
The GMA 340 is FAA TSO approved to C50c and C35d and JTSO approved to C50c and 2C35d. Also standard
is the marker beacon receiver with dual sensitivity and audio muting with automatic re-arming. 14V or 28V
operation, including the full rated range of headphone and speaker output power, is available without the
requirement for external voltage converters or dropping resistors. The GMA 340 is the standard version audio
panel as pictured on the cover of this manual. The GMA 340H is the helicopter version in which the pilot and co-
pilot control knobs on the front panel are reversed. The GMA 340 Dual ADF version, also pictured on the cover,
accepts two ADF audio inputs.
Features Summary:
•
User-friendly, intuitive front panel layout
•
LEDs indicate selected function
•
Six position intercom: pilot, copilot, four passengers
•
Three stereo headset amplifiers: one for pilot, one for copilot, and one for the passengers
•
Two stereo music source inputs (one in Dual ADF version)
•
Three selectable intercom operational modes
•
Selectable aural pushbutton annunciation (beep) for the crew.
GMA 340 Installation Manual
190-00149-01
SECTION 1
GENERAL INFORMATION
Page 1-1
Rev. L
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