COBHAM N301A-301 Configuration guide

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
SM Supplement Rev: 1.01 May 17, 2012 Page i
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Prepared By: Checked By: Approved By:
Revisions
Rev.
CR #
Date
Description of Change
1.01 DCA W12418 May 17, 2012 Added faceplate lighting specs.
1.00 Feb 23, 2012 Initial release
Geoff Melton
2012.05.17 
11:36:30 -07'00'
Barb Page
2012.05.2
4 
16:39:03 
-07'00'
Zack 
Pahlman
2012.05.
24 
17:20:47 
-07'00'
SEALED
2012.05.
29 
10:11:05 
-07'00'
Published on
June 01, 2012

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
SM Supplement Rev: 1.01 May 17, 2012 Page 1
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
This supplement contains installation and operation information that is unique to the N301A-300 Audio
Controller (N301A-300, N301A-301 and N310A-302). Installation and operation information common to
the N301A-000 base unit can be found in the SM45 Installation and Operation Manual.
Section 1 Description
The N301A-300 Audio Controller is identical to the N301A-000 with the following exceptions:
a) The backlight subassembly and TX LED annunciator are not installed.
b) The faceplate incorporates integral backlighting, TX annunciator and removable legends.
c) The MKR receive circuitry is replaced with HI/LOW IMPED discrete circuitry capable of sinking
≤100 mA at 30 VDC.
d) Rotary switch stop positions can be set by the customer.
Note: Refer to Figure 1 for identifiers (in italics) used on the N301A\300\403-0 Interconnect and
N301A\300\405-0 Connector Map drawings.
RADIO ICS
ICS
PVT TX HOT VOX
RX-ON
EMER
NORM
N301A
HI
LOW
IMPED
A
B
C
D
E
F
G
H
J
K
P
R S T
N
L
Figure 1
N301A-300 Front View
The N301A-300, N301A-301 and N301A-302 differ only in their faceplate lighting specifications, as
detailed below.
Model Faceplate Number
Color
Luminance
Backlighting Indicator Backlighting Indicator
N301A-300 55-35-205 Blue/White Green 1.0 ± 0.5
foot-lambert 15 ± 5 foot-lamberts
N301A-301 55-60-058 NVIS Green B NVIS Green B
N301A-302 55-55-032 NVIS Green A NVIS Green A

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
Page 2 May 17, 2012 SM Supplement Rev: 1.01
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
Section 2 Installation
For installation information and drawings, see SM45 Section 2. Select the appropriate revision of the
drawing for the serial number of the unit. The drawings specific to this derivative are listed below and can
be found at the end of this supplement.
2.1 Installation Drawings
DOCUMENT
REV.
DESCRIPTION
TYPE
SERIAL NO.
N301A\101\403-0 1.00 Audio Controller Interconnect All
N301A\101\405-0 1.00 Audio Controller Connector Map All
N301A\300\922-0 1.00 Audio Controller Mechanical Installation All
2.2 Legend Installation
Custom removable legends are to be ordered and installed by the customer.
Each N301A-300 requires a set of legends, either purchased individually (Part no. 55-06-xxxx, where
xxxx is the description of the legend, e.g., “COM1”) or as a legend kit (Part no. ACPLK-xxx). Each kit
consists of a number of printed legends and blanks (to suit customer requirements), and each legend
comes complete with a black gasket, either attached or loose in the bag.
If it is necessary to remove or replace a legend, carefully lever the legend away from the faceplate, and
insert the new or replacement legend as described above.
CAUTION
If the faceplate is damaged in any way during this process, light leakage
may occur, which will necessitate returning the unit to the manufacturer
for repair or replacement.
2.3 Stop Pin Installation
The N301A-300 is designed to enable the installer to adjust the number of positions that can be selected
on the rotary selector switch. The N301A is designed to be able to select up to 6 radio transmit positions
with the rotary selector switch. In applications where fewer than 6 radio selections are required, the
installer may wish to eliminate the ability of the selector switch to choose the unused positions. The
N301A-300 includes features that ease the adjustment of the number of rotary switch positions by the
installer. Use the procedure that follows to adjust the rotary switch.
When installing the legends for the first time, each legend must be fitted
with a black gasket to ensure uniformity of legend lighting. The gasket
fits into place on the back of the legend, but is easily dislodged or
damaged. Take particular care to ensure that it is properly positioned
before snapping the legend fully into place. If a replacement gasket is
required, the whole legend must be ordered.
Legend Gasket

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
SM Supplement Rev: 1.01 May 17, 2012 Page 3
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
To adjust the rotary switch stops, reference Parts List N301A\000\701-0 and Exploded View
N301A\000\904-0 in Maintenance Manual SM45 for the following procedure:
CAUTION
Parts are small and easily lost. Perform all operations at a work bench, not in the aircraft. Store all
parts in a plastic bag or other secure container while work is being performed.
CAUTION
Before removing knob set screws, ensure that Allen wrenches are not worn. Using an Allen
wrench with worn (rounded) corners will strip the screw head.
SHARP
CORNERS ROUNDED CORNERS
ACCEPTABLE UNACCEPTABLE
2.3.1 Using a 0.050” Allen wrench, remove knobs M6 from the front of the unit.
2.3.2 Using a 5/64” Allen wrench, remove knob M7 from the front of the unit.
2.3.3 Using a No. 1 Phillips screwdriver, remove pan head screws M8 from the front of the unit.
2.3.4 Remove faceplate.
2.3.5 Using a 9/16” hex socket or hollow shafted nut driver, remove hex nut and washer M211 from
rotary switch S201. The socket or nut driver must be at least 1” deep to accommodate the
shaft of the rotary switch.

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
Page 4 May 17, 2012 SM Supplement Rev: 1.01
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
HEX NUT
(P/O S201)
WASHER
M211
ROTARY
SWITCH
S201
CONNECTOR
J206
Figure 2
2.3.5 Up to eight rotary switch positions are available, numbered as shown on the faceplate in
Figure 3. (Rotary switch position numbers are shown for reference only.)
RADIO ICS
TX HOT VOX
RX-ON
EMER
NORM
N301A
1
2
34567
8
HI
LOW
IMPED
Figure 3
Identification of Rotary Switch Positions
(Rotary Switch position numbers shown for reference only)
2.3.6 Rotate the switch shaft clockwise as far as it will go.
2.3.7 Determine which rotary switch positions will be used on the faceplate to be installed.
2.3.8 Refer to Figure 4. Install a stop pin M212 in the hole whose number corresponds to the
lowest numbered rotary switch position that will be used.
2.3.9 Rotate the switch shaft counter-clockwise as far as it will go.

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
SM Supplement Rev: 1.01 May 17, 2012 Page 5
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
2.3.10 Install a stop pin M212 in the hole whose number corresponds to the highest numbered
rotary switch position plus one.
2.3.11 In the example shown in Figure 4, the rotary switch will be selectable for positions 1 through
8. Thus the stop pins are installed in positions 1 and 9.
ROTARY
SWITCH
S201
STOP PIN
M212 (2 PL)
WASHER
M211
HEX NUT
(P/O S201)
9876
4
3
2
1
5
ROTARY SWITCH S201
STOP POSITIONS
Figure 4
Note: Factory setting is shown.
2.3.12 Reinstall washer M211 and hex nut on rotary switch S201 and tighten securely. Do not
overtighten.
2.3.13 Position faceplate M5 so that connector pins on the back of faceplate mate with J206
connector on the front of the unit (see Figure 2).
2.3.14 Fasten faceplate M5 to front of unit using pan head screws M8.
2.3.15 Rotate rotary switch S201 fully counter-clockwise. Using a 5/64” Allen wrench, install knob
M7 onto S201 selector switch shaft with the knob arrow pointing to the leftmost position used.
Tighten both set screws securely. Do not overtighten.
2.4.16 Using a 0.050” Allen wrench, install knobs M6 on the three volume control shafts. Rotate the
shafts fully counter-clockwise and install one knob M6 on each. Ensure the knob indicator
lines are pointing to the 7 o’clock position. Tighten both set screws securely on each knob.
Do not overtighten.

N301A-300 Audio Controller
SM45 Installation and Operation Manual Supplement
Page 6 May 17, 2012 SM Supplement Rev: 1.01
ENG-FORM: 810-0111.DOT
CONFIDENTIAL AND PROPRIETARY TO COBHAM
2.5 Replacement Hardware
If parts are lost, consult the table below for replacement information.
Description
Designator
Part Number
Source
Washer, Flat M211 25-20-030 Cobham
Stop Pin M212 85-99-591 Cobham
Knob M6 40-00-239 Cobham
Knob M7 40-00-533 Cobham
Set Screw,
0.112-40 X 3/16 For M6 Knob (2 per knob) MS51021-102 Generic
Set Screw,
0.164-32 X 3/16 For M7 Knob (2 per knob) MS51021-132 Generic
Hex Nut For S201 Rotary Switch Replacement not available. Hex nut is supplied
by switch manufacturer as part of switch.
Section 3 Operation
For operation information, see SM45 Section 3.
Supplement ends