INSTRUCTION MANUAL

FOR

MX170C NAV / COMM TRANSCEIVER

MX170C NONE 1
Revision
8-2002 08/2008
DATE

TKM, INC
14811 N. 73rd STREET
SCOTTSDALE, AZ 85260

PART # MNO170C, REV. ONE

AUGUST 2008
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TABLE OF CONTENTS
COVER 1
TABLE OF CONTENTS 2

I. INTRODUCTION 3
A. Purpose of Equipment 3
B. Equipment Description 3
C. Specifications 5
DME Channeling 7

II. OPERATING THE MX170(B/C) 8

III. INSTALLATION 13
** Notice to Installer ** 13
** Continued Airworthiness (HBA 98-18) ** 13
** MX170(B/C) INTERCONNECT DIAGRAM ** 14

IV. PRINCIPLES OF OPERATION 15

V. MECHANICAL DISASSEMBLY 17

VI. ALIGNMENT AND TEST SPECIFICATIONS 18

VII. LAYOUTS, SCHEMATICS AND PARTS LISTS 31

Top Assembly 34
Computer Board 43
Rear Panel 52
Front Panel 68
Display 72
Driver 78
T/R Switch 83
COMM Receiver 89
COMM Synthesizer 104
Transmitter 112
NAV Receiver 125
NAV Synthesizer 138

QUICK REFERENCE OPERATION GUIDE 145

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I. INTRODUCTION
This manual contains information on the Michel MX170(C), manufactured by TKM, Inc.
The information includes installation, operation, mechanical and electrical descriptions
and alignment and test considerations. The MX170(C) is authorized by the Federal
Aviation Administration to TSO C34e, C36e, C37d, C38d, C40c and has met the test
requirements of RTCA/DO-160C.

A. Purpose of Equipment
The equipment is a 760 channel communication (COMM) transceiver for use in aviation
services and a 200 channel navigation (NAV) receiver to provide VOR / LOC signals to
navigational converters. The NAV receiver also provides frequency selection for remote
mounted Distance Measuring Equipment and Glide slope Receivers.

The MX170(C) is designed to be used as a direct replacement for the King KX170/
KX175. The unit is dimensionally identical to the King units and can therefore use
existing aircraft installations. Except for improved performance characteristics, the
unit is electrically interchangeable with the King units and will provide the proper audio,
navigation and channeling signals for existing installations. New installations can be
made using KX170A installation kits.

B. Equipment Description
The unit features digital (LED) displays for active (yellow) frequency channel and
standby (red) frequency channel for both COMM and NAV.

For channel selection a MHz knob and a KHz knob are provided. For 25 KHz
increments in COMM, a 25 KHz button is provided. To activate COMM or NAV
frequency selection, an N-C button is provided, a tic appears in the selected standby
channel display.

Channel selection operates on the standby channel only. When the desired channel is
indicated in the standby display, it may be placed into the active position by depressing
the ‘Flip-flop’ button located left of the displays. The active channel is then placed into
the standby position.

The NAV receiver features a VC-ID button to permit selection of voice or ident
reception. In the Ident condition a ‘tic’ is displayed on the active NAV channel display.

The COMM transceiver features a test button which overrides the squelch to verify
proper receiver operation and to allow reception of weak signals. Also, provided on the
active COMM display is a ‘tic’ to indicate transmitter power output.

Power switches are incorporated with the NAV and COMM volume controls. The
COMM is the master power switch and the NAV provides power switching for remote
navigation units.
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The MX170(C) is comprised of eight replaceable subassemblies. Five of the

subassemblies are contained in shielded modules in order to reduce radio frequency
interference. The five are the NAV receiver, the NAV synthesizer, the COMM receiver,
the COMM synthesizer, and the Transmitter.

The remaining three subassemblies are the Rear Panel Assembly, the Front Panel
Assembly and the Computer Board. The Rear Panel Assembly contains the Audio
Amplifier, Power Filter, and the T/R switching. The Front Panel Assembly contains the
digital displays, the function select switches and the volume controls. The Computer
Board contains the microprocessor, the memory, and program storage.

Also contained on the computer board are the audio processing circuits and the
channeling circuits.

The subassemblies are interconnected with plugs so that any module may be replaced
without the use of a soldering iron. For equipment repair it is recommended that
complete subassemblies be replaced.

As an aid to locating the defective subassembly a set of analog test points are provided.
The analog test points include the receiver tuning voltages, synthesizer control voltages,
and the AGC lines.
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C. Specifications

MX170(C) TRANSCEIVER

Mounting: Panel mounted, no shock mounting required.

Size: 6.312 x 2.600 x 14.15 inches w/

connectors (16.03 x 6.60 x 35.94 cm)

Weight: 4.9 lbs excluding external connector

and harness.

Power Requirements: 13.75 Vdc (or v w/CONV)

NAV and COMM Recv’r 1.7A
Max COMM Total w/
Transmit (Tone) 7.1A (6.2A unmodulated)

COMM Transceiver

Crystal Controlled: 760 channel

Frequency Range: 118.00 to 136.975 MHz

Frequency Stability: + .003%. –20 to 50C

Transmitter

VHF Power Output: 8 watts minimum, 50 ohm

Modulation: 85% capability with 90%

limiting provided.

Microphone: Dynamic mike containing

transistorized pre-amp or
carbon (must provide at least
120 m Vrms into 500 ohm load.

Sidetone: Adjustable up to 40 mw into

500 ohm headphones.

Duty Cycle: 1 minute on, 4 minutes off (20%)

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Receiver

Sensitivity: 1.5 uv (soft) will provide a 6 db

minimum signal plus noise to noise
ratio (KHz, 30% mod).

Selectivity: Typical 6 db at +/-7.5 KHz, 60 db at

+/- 17.5 KHz,

Spurious Responses: Down at least 70 db.

Squelch: Noise adaptive squelch with override.

.
AGC Characteristics: From 2 to 100.000 uV audio
output will not vary more than 1 db.

NAV Receiver

Crystal Controlled: 200 Channels

Frequency Range: 108.00 to 117.95 MHz

Sensitivity: 1.5 uv (soft) will provide a half-

flag indication.

Selectivity: Typical 6 db at +/- 15 KHz 60 db at

+/- 35 KHz,

Spurious Responses: Down at least 70 db.

Ident Filter: 15 db minimum

AGC Characteristics: From 26 to 100.000 uV audio

output will not vary more than 1 db

NAV Receiver Accuracy: Two sigma limit, +/- 1 degree

NAV Output: With LOC adjusted for 0.35 Vrms

VOR = 0.5 Vrms (typical) into
20K ohms or greater load impedance.
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Audio

Auxiliary Audio Inputs: Three (3) 500 ohms with 30 db

isolation between any two.

Frequency Responses: Within 6 db from 350 Hz to 2500 Hz

Headphone Output: 40 mw into 500 ohm

Speaker Output: 4.5 Vrms into auxiliary input

produces 5 watts audio output.

DME Channeling

M0 M1 M2 M3 K0 K1 K2 K3 50 KHz

108 - - 0 - .0X 0 0 - - .X0 -

109 - - - 0 .1X 0 0 0 - .X5 0
110 0 - - - .2X 0 0 0 0
111 0 0 - - .3X - 0 0 0
112 0 0 0 - .4X - - 0 0
113 - 0 0 0 .5X 0 - - 0
114 0 - 0 0 .6X - 0 - -
115 - 0 - 0 .7X - - 0 -
116 0 - 0 - .8X - - - 0
117 0 0 - 0 .9X 0 - - -
NOTE: (-) = OPEN, (0) = GROUND

ILS Energize: OPEN for VOR, GROUND for ILS

GS GS GS GS GS GS GS GS GS

108 109 110 111 0.1 0.3 0.5 0.7 0.9

108 0 - - - .0X - - - - -
109 - 0 - - .1X 1 - - - -
110 - - 0 - .2X - - - - -
111 - - - 0 .3X - 1 - - -
112 - - - - .4X - - - - -
113 - - - - .5X - - 1 - -
114 - - - - .6X - - - - -
115 - - - - .7X - - - 1 -
116 - - - - .8X - - - - -
117 - - - - .9X - - - - 1
NOTE: (-) = OPEN, (0) = GROUND, (1) = CONNECTED TO G / S
Switching Line
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II. OPERATING THE MX170(B/C)

Operating controls for the MX170(C) are located on the unit front panel or through three
access points in the case (See Figure 2)

The unit front panel is shown in Figure 1. The left-hand COMM (yellow) readout
indicates the active COMM frequency and the right hand COMM (red) readout indicates
the standby COMM frequency. The left-hand NAV (yellow) readout indicates the active
NAV frequency and the right hand NAV (red) readout indicates the standby NAV
frequency. A ‘tic’ readout is provided on the upper left-hand corner of the first digit of
each of the four frequency readouts.

The active COMM ‘tic’ indicates the presence of transmitter power.

The standby COMM ‘tic’ indicates that the Frequency Selection knobs will control
COMM standby frequency.

The active NAV ‘tic’ indicates that the NAV receiver is in the Ident Mode.

The standby NAV ‘tic’ indicates that the Frequency Selector knobs will control NAV
standby frequency.

Power Application. The COMM volume control contains the master power switch and
activates the COMM functions. The NAV volume control contains a power switch for
the remote NAV units. In order to activate all COMM and NAV functions, both volume
controls must be turned on.

Frequency Selection. The N/C button is used to activate either the COMM or the NAV
frequency selection as indicated by the appropriate ‘tic’ display. The MHz and KHz
controls can then be used to select a desired standby channel. In COMM the ‘25’ button
is used to advance the frequency by 25 KHz.

After the desired standby frequency is selected, it may be transferred to the active
position by pressing the desired ‘flip-flop’ buttons left of the displays. The active and
standby channels will be transposed each time the button is pressed.

Ident/Voice Selection. The VC-ID button can be used to select a tone filter in order to
receive voice signals on the NAV receiver. The switch is also used for frequency storage
as described in Frequency Storage.
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Test. The TEST button is a dual function switch. In normal operation, it is used to
override the squelch to verify receiver operation and to receive weak signals. The switch
is also used for frequency storage as described below.

Transmit. The transmit mode on the transceiver is selected by grounding the MIC Key
line on the unit’s rear panel.

Clearing all frequency presets. To clear the entire memory, both NAV and COMM,
except for factory presets:
1. Turn radio off.
2. While holding down the TEST button, turn the radio on. The unit will reset to factory
preset default channels in both active and standby (COMM 121.50/120.00) (NAV
108.00/112.00).

Frequency Storage. The MX170C NAV COMM allows up to 50 NAV and 50 COMM
preset frequencies to be stored in the memory for recall. The use of memory presets is
described in the following procedures.

Examining / Changing / Inserting / Deleting frequency presets. These operations on

individual frequency presets are accomplished in EDIT mode. To enter EDIT mode, turn
on the power to the radio while holding the VT button depressed. When the radio is in
EDIT mode, the active displays show the sequential number of the preset (1,2,3,etc.) and
the standby displays show the actual preset frequency.

EDIT mode operations can be performed on either the COMM or NAV preset list,
according to where the tuning tic indicator is displayed. The tuning tic appears
immediately to the left of the COMM or NAV standby displays. Pressing the N-C button
toggles between NAV and COMM preset editing.

Examining presets (EDIT MODE). Pressing the COMM F-F button will step to the next
frequency in the preset list. Pressing the TEST button will step to the previous frequency
in the preset list. Pressing COMM F-F when the last preset is displayed will cause the
first preset to display. Similarly, pressing TEST when the first preset is displayed will
cause the last preset to display. Warning: When there is only one preset in the list, the
radio will not appear to “do anything” when the COMM F-F or TEST is pressed. This is
because the current, previous, and next presets are all the same preset.

Changing a preset (EDIT MODE). Press COMM F-F or TEST until the preset to be
changed is displayed. Dial in the new preset frequency using the tuning controls and
press either COMM F-F or TEST.

Inserting (Adding) a preset (EDIT MODE). Press COMM F-F or TEST until the desired
insert point is displayed (the new preset will be inserted AFTER this insert point). Dial
in the desired frequency using the tuning controls and press NAV F-F. Remember that a
preset list may contain a maximum of 50 entries. Inserting commands that would cause
this limit to be exceeded are ignored.
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Deleting a preset (EDIT MODE). Press COMM F-F or TEST until the preset to be
deleted is displayed. Then press the VC – ID switch to delete. If the deleted preset was
not at the end of the list, all the presets that followed it are renumbered. Each preset list
(NAV and COMM) must always contain at least one entry. If there is only one entry
remaining in a preset list, it may not be deleted (It can be changed to another frequency).

Frequency preset, normal operation. At any time the radio is in normal operation (Not
EDIT MODE), COMM preset frequencies may be called into the standby frequency
display by pressing COMM F-F while the TEST button is depressed. During the time
that both buttons are held simultaneously depressed, the reference number for the preset
appears in the active window. Each time this operation is repeated, it will copy the
“next” preset to the COMM standby frequency.

NAV preset operation is similar, with the exception that presets are retrieved by pressing
and holding the NAV F-F while pressing the VC – ID.
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III. INSTALLATION

The MX170C is designed to be an exact replacement for the KING KX170A and similar
units. As a replacement unit, the MX is inserted directly into the mounting tray for the
KX170A and tightened down with an allen wrench (5/64).

For new installations, the installation instructions for the KX170A should be used.

Equipment removal is accomplished by rotating the clamp screw counterclockwise a few

turns until it can be felt that the clamp screw is disengaged. Excessive torque on the
clamp screw will result disassembly of the clamp. After the clamp has been disengaged
the unit may be extracted by rocking the unit from side to side. The knobs should not be
used as extraction handles. A King Extraction tool # 071-6045-00 is also an acceptable
extraction device. Another method for extraction of a tight unit would be to rotate the
clamp screw counterclockwise until significant resistance is noted, the clamp screw can
then be pulled forward to expose the screw head. Grasp the screw head with a suitable
device and extraction force can be applied. Excessive side to side motion should not be
applied to the clamp screw.

**** NOTICE TO INSTALLER ****

The TKM MX170C NAV/COMM is authorized by the FAA to TSO C34e, C36e, C37d, C38d, and C40c.
The product is an incomplete system. In order to achieve a complete TSO quality system, the MX170C
must be installed to configure in conjunction with a TSO C37/C38 authorized antenna and a TSO C34e
authorized navigation receiver. It is the responsibility of the installer to ensure proper installation.

****CONTINUED AIRWORTHINESS (HBA 98-18)****

Permission is hereby given to installers approved by the recognized aviation authority to reference excerpts
from the installation instructions provided by TKM Inc. in order to fulfill documentation requirements for
Instructions for Continued Airworthiness (ICA). Adequacy of the documents should not be assumed by
this permission. ICA documentation rests solely with the ICA applicant. The MX170C product is ‘Repair
on Condition Only’.
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MX170(B/C) INTERCONNECT

The following table lists the pin description for the MX170C external interconnect:

Pin # Description Pin # Description

1 NAV A + 22 DME M0
2 GS + 23 DME M1
3 VOR/LOC Signal 24 DME M2
4 ILS ENABLE 25 DME M3
5 50 KHz GS 26 NAV A+ Switched
6 0.1 MHz GS 27 DME K0
7 0.3 MHz GS 28 DME K1
8 0.5 MHz GS 29 DME K2
9 0.7 MHz GS 30 DME K3
10 0.9 MHz GS 31 DME 50 KHz
11 108 MHz GS 32 DME Common
12 109 MHz GS 33 VOR Test
13 110 MHz GS 34 Phones, Comm
14 111 MHz GS 35 NAV Audio
15 Aux Audio –1 36 Aux Audio -1
16 Aux Audio –4 37 ICS
17 A / C Power Switched 38 Not Used
18 13.5 vdc Input 39 Mic Audio
19 Ground 40 Mic Key
20 A / C Power 41 Speaker
21 Power/Speaker Ground 42 COMM FLIP-FLOP*

• Requires addition of internal resistor R53 on computer board.

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IV. PRINCIPLES OF OPERATION

For ease of service the MX170(B/C) has been designed into 8 replaceable modules. The
modules are:

A. Front Panel Assembly

B. Rear Panel Assembly
C. Computer Board
D. NAV Receiver
E. COMM Receiver
F. NAV Synthesizer
G. COMM Synthesizer
H. Transmitter

A. Front Panel Assembly-Dwg. SS1740

The front panel includes the four frequency displays, a photocell for automatic brightness
control, 7 push buttons, two volume controls with proper switches and two frequency
selecting switches. The displays and controls are connected to the display driver board
through pin and socket connectors and to the computer board with a ribbon cable.

B. Rear Panel Assembly-Dwg. SS1750

The rear panel includes the power converter, the audio circuits and T/R switching
circuits. Refer to Dwg. SS1750.

IIA is both the audio preamplifier and summing point for all audio inputs except the
microphone input. IIB is the second audio amplifier. The input to this amplifier is
selected between the first audio and the microphone input with 12A or 12B. 12C is used
as an inverter to activate 12A. The selected audio is volume comprised in I3 and applied
to the push-pull audio output of IC’s 14 and 15. Q1, Q2, and K1 provide switching to
couple the audio amplifier to the speaker for receiving operations or the transmitter for
transmit operation.

The power supply consists of an input filter L1, C29, and C30, a +5 volt regulator and a
voltage converter. The +5 volt regulator is designed around a 3524 pulse width
modulator with a crowbar protection circuit. Q3 is the power switch in the circuit. Q4
and Q5 with T1 form the converter circuit and provide a 20 volt p-p square wave for the
output rectifiers. I8 provides a regulated +15 vdc output and D9 and D10 provide an
unregulated –20 vdc output.

The T/R switch, Dwg. SS1731 contains switching diodes D1 and D2 and a low pass filter
L1, C1, L2, C4. In receive, the diode is forward biased to couple the receiver to the
antenna. In transmit, the T/R line is open circuited to permit the transmitter signal to
generate a reverse bias on the diode to the peak value of the transmitter signal.
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C. Computer Board-Dwg. SS1760

The computer board contains 3 basic sections:

1. Computer
2. Analog Processing
3. Channeling Circuits

1. Computer
The computer is comprised of the processor (I6), the Program Prom (I5), the Memory
Ram (I4), the address decoder (I7), the oscillator (I3), and the read/write decoder (I8).
The RAM contains a lithium battery that will support the memory indefinitely.

2. Analog Processing
The Analog Processing functions include noise detection, phone amplification, tracking,
squelch, Ident code filtering and transmitter monitoring.

I12 B is an adjustable gain amplifier used to track receiver tuning to synthesizer

frequency. I12A and I12 D is a 2 pole band pass filter to separate noise from audio
signals. The noise is detected with D4; the noise level is used to inhibit the carrier
squelch threshold as determined by I13 B.

I13A detects the voltage on the T/R switch. When a large negative voltage is detected, an
active signal is applied to I1 to turn on the transmit “Tic”.

3. Channeling Circuits
The channeling circuits are comprised of digital latches and output drivers. I16 provides
the Slip code channeling for the DME, I15 provides Glide Slope KHz output drive, and
I14, 17 provide Glide Slope MHz output drive in addition to the ILS enable drive.

D, E. NAV(Dwg. SS18677 and COMM(Dwg. SS1866) Receivers

The NAV and COMM receivers are functionally the same. The only difference between
the two receivers is the RF tuning, the AGC time constant and a tuning voltage sensor in
the COMM receiver which reduces the receiver gain during Transmitter actuation.

D1, 2, 3 and 4 provide RF tuning and are tracked to the appropriate Frequency
Synthesizer using circuitry on the computer board.

Q1 is the RF amplifier, D8 is a diode quad used as a balanced mixer, Q2 is the first IF

amp, I1 is the second IF amp, and D5 is the detector.

I2 A is the first agc amp and I2 D is the second agc amp. I2 B and I2 C are audio
amplifiers.

The crystal filter is a single assembly containing 8-poles.

D7, with associated components, provides dynamic noise limiting.

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F, G. NAV(Dwg. SS2714) and COMM(Dwg. SS2716) Synthesizers

The NAV and COMM synthesizers are identical except for tuning and an additional
output is provided in the COMM synthesizer to drive the transmitter.

I3 receives digital frequency information from the computer and sets the internal
frequency divide ratios to determine the desired output frequency. I3 also contains a
phase detector to generate an error signal for the voltage-controlled oscillator (VCO) I2.
I1 is used to amplify and filter the error signal for the VCO.

Q4 is a buffer amplifier which isolates the VCO from the divider circuits. I4 is a high
frequency divider which is used in conjunction with and controlled by I3.

Q1, Q2, and Q3 are buffer amplifiers which provide the proper output levels and isolation
from the VCO.

Q5 is a T/R switch which provides power switching for Q3 as well as the first amplifier
transistor in the transmitter.

H. Transmitter(Dwg. SS1881)
The transmitter consists of 4 RF power amplifiers. The first amplifier Q4 is gated by
power received from the frequency synthesizer. Q1, Q2, and Q3 form a broadband
collector modulated transmitter chain.

V. Mechanical Disassembly

The first step in mechanical disassembly is to remove the top cover by removing the nine
screws around the sides and rear of the cover. The cover may then be pried up at either
rear corner, lifted slightly and slid away from the front panel.

The Computer Board is removed by removing the connectors and then the six spacers
holding the Computer board. The board may then be lifted from the unit.

The Front Panel may be removed by removing four screws from the sides and bottom.

The Rear Panel is removed by removing two screws on the bottom of the unit and one
screw from each side of the unit. The Transmitter power lead can be removed by
loosening the attaching screw.

The R-F modules may be removed by removing the mounting screws.

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VI. Alignment and Test Specifications

Adjustments are made on the total unit on a final test basis and on an installation basis.

Installation adjustments are accessible without removing the cover and include a side
tone level adjustment, a microphone gain adjustment, and an audio gain adjustment
(See Figure 2).
Engineering Bulletin
August 18, 1992

Bulletin: #081792

Subject: Requirement for Spectrum Analyzer to repair TKM NAV / COMM Radios.

A spectrum analyzer is required only for alignment of the Frequency Synthesizer module.
If Synthesizer repair is made on a replacement basis, it is not necessary to have a
spectrum analyzer for field service.

Other adjustments for the MX170(B/C) which are not normally adjusted on installation
but may require adjustment different from factory set levels include the squelch level, the
dimmer and the NAV demod level.

Module Alignment
A. Front Panel Assembly
The front panel requires no alignment.

B. Rear Panel Assembly

The rear panel contains two potentiometers that are adjusted as follows:
1. Microphone Gain (R10). Apply .30 Vrms at 1000 Hz to pin 39 of P1. Adjust R10 so
that 12 v p-p is output to the transmitter modulation line.
2. Sidetone Level (R33). Apply .30 Vrms at 1000 Hz to pin 39 of P1 and adjust R33 so
that 1.0 vrms appears across a 500 ohm load connected to pin 34 of P1.

C. Computer Board
The computer board contains mostly system alignment adjustment which can be set only
with a complete unit. The clock frequency, however, can be set on the board level.
1. To alter the clock frequency, adjust C2 so that frequency measured on pin 6 of U3 is
4,032,000 + 10 Hz at 70 degrees ambient temperature.

D. NAV Receiver
1. Apply +15 vdc and –30 vdc to appropriate input leads, local oscillator signal at 3.0 + 2
dbm and a 0 to 14 vdc variable voltage source to Vt.
2. IF Alignment (L2, L3, L4). Apply =7.0 vcd to Vt, 117.90 MHz at –90 dbm to RF in
and 96.50 MHz at +3 dbm to L. O. Adjust L2, L3 and L4 for minimum voltage
reading on Vagc. Apply amplitude modulation of 30% and monitor DMD output.
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3. As the modulation frequency is adjusted from 1.0 to 12.0 KHz the DMD level shall be
constant +1 db. Adjust L2 and L3 as necessary to keep DMD level constant.
4. RF Alignment (T1, T2, L1, T3). With conditions the same as in IF Alignment, but
modulation set to 0, adjust turn spacing on T1, T2, L1 and T3 so that Vagc reading is a
minimum.
5. Change RF to 108.00 MHz and L.O. to 86.60 MHz. Adjust Vt for minimum Vagc.
6. DMD Level (R25). With conditions the same as in IF Alignment apply a standard
centered LOC modulation and adjust R25 for .35 Vrms on DMD output.

E. COMM Receiver
1. Apply +15 vdc and –30 vdc to appropriate input leads, set local oscillator signal to 3 +
2 dbm and a 1 to 15 vdc variable voltage source to Vt.
2. IF Alignment (L2, L3, L4). Apply +10 vdc to Vt, 135.975 MHz at –90 dbm to RF and
157.175 MHz to L.O. Adjust L2, L3, and L4 for minimum voltage reading on Vagc.
Apply amplitude modulation of 30% and frequency is adjusted from 1.0 to 12.0 KHz
the DMD level shall be constant + 1 db. Adjust L2 and L3 as necessary to keep DMD
level constant.
3. RF Alignment ( T1, T2, L1, T3). With conditions the same as in IF Alignment but
modulation set to 0, adjust turn spacing on T1, T2, L1, and T3 so that Vagc reading is
a minimum.

F. NAV Synthesizer
1. Apply +15 vdc and 1 Mhz to appropriate module input. Set R3 to midrange. Digitally
input, using Computer board or equivalent, the proper coding for 96.50 MHz. Verify
correct output frequency. Adjust turn spacing on T1 so that Vt = 7.00 vdc. Digitally
input coding for 86.60 MHz. Vt shall be 2.50 +.30 vdc.
2. Digitally input coding for 91.60 MHz and monitor output on a spectrum analyzer.
Adjust R3 so that 50 KHz sidebands are nulled.

G. COMM Synthesizer
1. Apply +15 vdc and 1 MHz to appropriate module input. Set R3 to midrange.
Digitally input, using Computer board or equivalent, the proper coding for 157.30
MHz. Verify correct output frequency. Adjust turn spacing on T1 so that Vt = 10.00
vdc. Digitally input coding for 139.40 MHz. Vt shall be 5.00 + .50 vdc.
2. Digitally input coding for 149.00 MHz and monitor output on a spectrum analyzer.
Adjust R3 so that 25 KHz sidebands are nulled.

E. Transmitter
The transmitter does not normally require alignment but tests should be performed to
verify proper operation.
1. Connect the transmitter to a properly aligned COMM Synthesizer and connect a 50
ohm load to the Transmitter output. Monitor the output power level to verify that it is
at least 9.0 watts without modulation across the frequency range of 118 to 136 MHz.
Apply at least 80% modulation at 1.0 KHz and monitor the output with a spectrum
analyzer to verify that no parasitic oscillation is present. If problems are encountered,
consult the factory.
 20

2. Apply at least 80% modulation at 1.0 KHz and monitor the output with a spectrum
analyzer to verify that no parasitic oscillation is present. If problems are encountered
consult the factory.

System Alignment
When all modules are aligned and assembled into a system, it is necessary to make
receiver tracking, VOR / LOC converter and squelch adjustments.
1. COMM receiver tracking is accomplished by selecting 118.00 MHz as the active
channel, applying a 10 uV RF input signal at 118.00 MHz, and adjusting R47 on the
Computer Board for minimum reading on COMM AGC line.
2. NAV Receiver tracking is accomplished by selecting 108.00 MHz and adjusting R33
on the Computer board for a minimum reading on NAV AGC.
3. Carrier squelch is adjusted by applying an unmodulated carrier at 3.0 uV to the
COMM receiver and adjusting R18 on the Front Panel, to just break squelch.
4. Noise inhibit is adjusted by applying a carrier with 30% modulation at 6.666 KHz to
the COMM receiver and adjusting R65 on the computer board so that a 12 uV signal
will just break squelch.
5. Demod output level is set by R29 (Demod Level) on computer board.
The 1020 Hz Filter is adjusted by monitoring the audio output and applying a 1020 Hz
modulation to the NAV Receiver input. With “Voice” selected adjust R12 (1020 Hz)
for minimum tone output.
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SCHEMATICS, LAYOUTS, AND PARTS LISTS

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