Northern Airborne Technology 270 - Manual (Page 9)

SM270 Rev. 4.10 Model 270 Universal Interface Amplifier Manual
Section 1 Description
1.1 Introduction
This manual contains information on the Model 270 Universal Interface Amplifier. All
derivative products will be covered by manual supplements, which can be obtained from
NAT as required.
Information in this section consists of purpose of equipment, features and specifications.
1.2 Purpose of Equipment
The Model 270 Universal Interface Amplifier is designed to provide multipurpose
amplification and switching functions for varying radio, microphone, and custom audio
interface needs. The unit is designed to interface radios to operator headsets and
microphones and provide specialized switching functions such as voice activated
switching, radio PTT switching, or other interface functions. The Model 270 can be used
as a primary amplifier for an aircraft or vehicle operator station or it can be used as an
auxiliary amplifier for interface or other applications.
1.3 Features
The Model 270 has Audio, MIC, and Spare Input channels. The Audio Input (receiver)
channel is a balanced (differential) type input; the MIC and Spare Input channels are
single-ended (ground referenced) and designed for interface to commercial DC-biased
microphones or similar low-level audio signals from virtually any source.
Signals applied to the Audio Input channel are reproduced at the Audio Output channel,
the MIC Input channel is reproduced at the MIC Output channel, and the Spare Input is
reproduced at the Spare Output channel. Signals applied to the MIC Input channel can
also be routed to the Audio Output channel by adjusting the MIC SDTN level adjustment
trimmer for the desired audio level.
The Model 270 also includes a multipurpose switching relay capable of performing
different functions. Model 270 functions and specifications are outlined in Sections
1.4.1.1 through 1.4.1.4. A discrete input is provided for controlling the relay in a keyed
mode (e.g. ground to activate or PTT), or alternate action (e.g. latched to another
position with each ground applied). VOX controlled mode (e.g. by audio signals applied
to the Spare Input) is also available. The switching relay can be used to control radio
keying, audio switching, interphone mode switching, music muting, or other specialized
functions as needed.
Dec 12, 2006 Page 1-1
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