COBHAM 265-005 Technical Document

DOCUMENT NUMBER 265-16-3 REVISION 1.00
EQUIPMENT MANUAL
AREA MICROPHONE PREAMPLIFIER
MODEL 265-005
PRODUCT FUNCTIONAL SPECIFICATIONS
AND INSTALLATION MANUAL
CONFIDENTIAL AND PROPRIETARY TO COBHAM
IMPORTANT NOTICE
Chelton Avionics Inc. doing business as Wulfsberg
Electronics Division is responsible for full distribution and
revisions of ICA's (Instructions for Continued Airworthiness).
For inquiries regarding the content and currency of this
manual contact Wulfsberg Electronics Division, 6400
Wilkinson Drive, Prescott, Arizona, 86301. Telephone (928)
756-1615 or refer to the following website:
www.wulfsberg.com for more information.
SEALED
2013.06.03 
15:04:41 
-07'00'
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

265-16-3 CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page a
CHANGE RECORD
DATE CHANGE CHECK APPROVAL
6-3-13
DCA W13149. Initial release.
Geoff Melton
2013.05.29 
15:00:09 
-07'00'
Barb Page
2013.05.2
9 
15:55:34 
-07'00'
Zack 
Pahlman
2013.05.30 
17:24:44 
-07'00'
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

265-16-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page b
TABLE OF CONTENTS
Page
1.0 OPERATING INSTRUCTIONS AND EQUIPMENT LIMITATIONS....................1
2.0 SPECIFICATIONS............................................................................................2
3.0 INSTALLATION PROCEDURES, WIRING DIAGRAMS,
AND LIMITATIONS...........................................................................................3
3.1 ELECTRICAL.............................................................................................3
4.0 CALIBRATION AND MAINTENANCE PROCEDURES.....................................5
Tables
Table 1 P1 Connector Pinout..................................................................................3
Table 2 Environmental Qualification Form...............................................................6
Figures
Figure 1 Outline Drawing, Model 265-005 Area Microphone Preamplifier ...............4
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

265-16-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page c
Configuration Identification
No MODs exist for Model 265-005.
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

EQUIPMENT MANUAL 265-16-3 REV. 1.00
265-16-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page 1
EQUIPMENT MANUAL
MODEL 265-005
AREA MICROPHONE PREAMPLIFIER
1.0 OPERATING INSTRUCTION AND EQUIPMENT LIMITATIONS
This document makes references to dB Systems, Inc. and NAT Seattle, Inc. Please note that dB
Systems, Inc. and NAT Seattle, Inc. have been changed to Cobham. For references to dB Systems,
Inc. or NAT Seattle, Inc. herein, substitute Cobham.
The conditions and tests required for TSO approval of this article are minimum performance standards.
It is the responsibility of those installing this article either on or within a specific type or class of aircraft
to determine that the aircraft installation conditions are within the TSO standards. TSO articles must
have separate approval for installation in an aircraft. The article may be installed only if performed
under 14 CFR part 43 or the applicable airworthiness requirements.
The Model 265-005 Area Microphone Preamplifier is designed to detect and amplify acoustic cockpit
signals for routing to cockpit voice recorders.
Models 265-005 includes an internally mounted microphone that receives acoustic input signals at the
microphone opening located at the front of the enclosure.
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

EQUIPMENT MANUAL 265-16-3 REV. 1.00
265-16-3 CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page 2
2.0 SPECIFICATIONS
Amplifier Gain: Adjustable from 16 dB to 36 dB
Output Level: 0.50±0.05VRMS into 600 Ωwhen the acoustic input level is
94dB SPL above 20µPascals
Amplifier Frequency Response: Flat within 3 dB, from 100 to 10,000 Hz.
Acoustic Frequency Response: Flat within 5 dB, from 150 to 8,000 Hz.
Amplifier Distortion (THD+N): Less than 1 percent
Acoustic Distortion (THD+N): Less than 5 percent
Microphone Output: 0.5 VRMS into 600 ohms (nominal) 1.0VRMS into 600 (max)
Power Supply: 28VDC, 30mA
Operating Temperature: From -55°C to +70°C
Operating Altitude: To +55,000 feet
Qualifications: FAR Part 21, TSO-C139, TSO-C123b, Eurocae ED112, RTCA DO-
214 and RTCA DO-160E Environmental Category:
[(A2)(F2)X]BBB[TU]EWXDFXZ[BZ]AZ[ZC][WWR]H[B3F3X]XAAX
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

EQUIPMENT MANUAL 265-16-3 REV. 1.00
265-16-3 CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page 3
3.0 INSTALLATION PROCEDURES, WIRING DIAGRAMS, AND LIMITATIONS
Installation dimensions of the Model 265-005 are shown in Figure 1. The case must be grounded to
the aircraft structure, either directly or through a grounding strap of appropriate width according to its
length. The case is finished with electrically insulating and conductive films. The mounting areas of
the footprint are cleared of the insulating finish so that the conductive finish is exposed.
NOTE: The finish should not be removed because it prevents corrosion.
The Model 265-005 can be mounted in any position. No shock vibration isolators are required.
3.1 ELECTRICAL
Connections to the Model 265-005 Area Microphone Preamplifier are made through a 9-pin “D”
subminiature connector (with interfacial seal for moisture resistance). The mating connector is a
standard industry part. The mating connector part number is Positronic RD9F10GE0 (supplied with
FC7522D contacts). This connector is compliant with military part number M24308/2-1 per
MIL-C-24308.
The Model 265-005 amplifier’s input and output wires should be placed no less than 12 inches away
from any 400 Hz current carrying power lines or lines carrying audio frequency interference onboard
the aircraft. This will prevent magnetic coupling of AC noise currents into the audio lines.
Twisted and shielded wire must be used for the audio connections from the microphone to the amplifier
and from the amplifier to the transmitter and/or interphone amplifier. AWG 22 to 26 wire size is
recommended.
NOTE: Audio cable shields must be grounded at one end only. If audio cable shields are grounded at
both ends AC noise currents can flow through the shield and inductively couple noise into the audio
wires. If additional RF shielding is required, use double shielded wire with the inner shield grounded at
one end and the outer shield grounded at both ends.
TABLE 1: P1 CONNECTOR PINOUT
PIN SIGNAL PIN SIGNAL
1 SPARE 6 28VDC RETURN (GND)
2 +28VDC IN 7 SPARE
3 N/C 8 N/C
4 AUDIO OUTPUT HI 9 AUDIO OUTPUT LO
5 AUDIO SHIELD (CHASSIS GND)
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

EQUIPMENT MANUAL 265-16-3 REV. 1.00
265-16-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page 4
TEXT ORIENTATION
THIS WAY
REAR VIEW
BAR
CODE
TEXT ORIENTATION
THIS WAY
TEXT ORIENTATION
THIS WAY
TOP
TOP VIEW
FRONT VIEW
TOP
BOTTOM
SIDE VIEW
BOTTOM
BOTTOM VIEW
ESD CAUTION DECAL
BAR CODE LABEL
TSO/MOD
LABEL
TAMPER PROOF LABEL
DZUS FASTENERS
(4 PL) MS25212
P1, "D" SUBMINIATURE CONNECTOR (9 PIN)
POSITRONIC PART NUMBER MD9P5R50T20
WITH JACK SCREWS. MATES WITH RD9F10GE0
5.750 +0/-0.030 [146.05]
1.481
+0/-0.030
[37.62]
3.507 [89.07]
0.414
0.093
0.750
[19.05]
5.365 [136.27]
0.187
1.310
[33.274]
2.120 [53.85]
Ø0.42
FILE: 265-005_922-0101.DWG
Figure 1. Outline Drawing, Model 256-005
These commodities, technology or software are controlled in accordance with the United
States Export Administration Regulations, Export Classification Control Number(ECCN)
7E994. When exporting, diversion contrary to U.S. law is prohibited.

EQUIPMENT MANUAL 265-16-3 REV. 1.00
265-16-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page 5
4.0 CALIBRATION AND MAINTENANCE PROCEDURES
Calibration procedures are included in Document No. 265-4-1, Acceptance Test Procedure.
Maintenance of Model 265-005 is “on condition” only. Periodic maintenance of this product is not
required. Assembly drawings, parts lists, and schematics are included in this manual for use during
troubleshooting and repair.
5.0 AIRWORTHINESS LIMITATIONS
The Airworthiness Limitations section is FAA approved and specifies inspections and other
maintenance required under 14 CFR §§ 43.16 and 91.403, unless an alternative program has been
FAA approved.
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.

EQUIPMENT MANUAL 265-16-3 REV. 1.00
265-16-3
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Page 6
Table 2. Environmental Qualification Form
NOMENCLATURE: AREA MICROPHONE PREAMPLIFIER
TYPE/MODEL/PART NO.: MODEL 265-[ ] TSO NUMBER: TSO-C139, TSO-C123b
MANUFACTURERS SPECIFICATION AND/OR OTHER APPLICABLE SPECIFICATION:
Document No. 265-16, Equipment Manual
MANUFACTURER: NAT SEATTLE, INC.
ADDRESS: 22125 17
TH
AVE SE, SUITE 107, BOTHELL, WA 98021
Conditions
DO-160E
Section/
Paragraph
Description of Conducted Tests
Temperature and altitude
Low temperature
High temperature
In-flight loss of cooling
Altitude
Decompression
Overpressure
4.0
4.5.1
4.5.2
4.5.3
4.5.4
4.6.1
4.6.2
4.6.3
Equipment was meets requirements of Category F2
(see also temperature variation)
(see also temperature variation)
(see also temperature variation)
No cooling required, no test conducted (identified as
Category X)
Altitude tested to +70,000 ft.
Decompression tested to +55,000 ft.
Tested to -15,000 ft. Equipment meets the
requirements of Category A2.
Temperature variation 5.0 Equipment meets requirements of Category B
Humidity 6.0 Equipment meets requirements of Category B
Operational shocks and
crash safety
Operational shocks
Crash safety
7.0
7.2
7.3
Equipment meets requirements of Category B,
paragraphs 7.2 and 7.3.
Equipment was tested while operating.
Vibration 8.0 Equipment meets requirements (without shock
mounts) of Categories T and U. Curve R extended
to 2,000 Hz.
Explosion proofness 9.0 Equipment identified as Category E by analysis.
Waterproofness 10.0 Equipment was tested to and meets requirements of
Category W.
Fluids susceptibility 11.0 Equipment identified as Category X, no test required.
Sand and dust 12.0 Equipment was tested to and meets requirements of
Category D.
These commodities, technology or software are controlled in accordance with the United States Export Administration Regulations, Export Classification
Control Number(ECCN) 7E994. When exporting, diversion contrary to U.S. law is prohibited.