Maxon SD170EX, SD171EX, SD174EX Service Manual

Service Manual SD170EX Series

Amendment Record Sheet

All amendments to this manual should be incorporated as soon as they are received and
recorded below:

Issue No. Effective

Date

Reason for Change Date Signature

All Engineering Bulletins relevant to this product should be placed at the rear of this binder.

Please ensure that this manual is updated with any replacement pages, which may accompany

these Engineering Bulletins.

Always read all Engineering Bulletins before carrying out work on a radio.

Please read the WARNINGS on the next page before referring to subsequent sections.

Page 2 of 38

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Service Manual SD170EX Series

Warnings

1. WARNING! NEVER connect the transceiver to an AC outlet. This may pose a fire hazard

or result in an electric shock.

2. NEVER operate the radio transmitter without a suitable artificial load or antenna

connected.

3. NEVER connect the transceiver to a power source of more than 13.8V.

4. NEVER dispose of the battery in fire – it can explode causing personal injury.

5. NEVER attempt to disassemble the battery or remove its case material or charging

contacts. Do not short the battery terminals.

6. NEVER expose the transceiver to rain, snow or any liquids.

7. NEVER modify a radio or accessory except as instructed in the service manual,

engineering bulletins or formal communication as this may invalidate any warranty,

guarantee or type approval.

8. USE the supplied microphone only. Other microphones have different pin assignments

and may damage the transceiver.

9. DO NOT use or place the transceiver in areas with temperatures below -30°C or above

+60°C, In areas subject to direct sunlight, such as the dashboard.

10. DO NOT hold the radio in such a manner that the antenna is next to, or touching,

exposed parts of the body, especially the face or eyes, while transmitting.

11. DO NOT allow children to operate transmitter-equipped radio equipment.

12. DO NOT operate the radio near unshielded electrical blasting caps or in an explosive

atmosphere, unless it is a type especially designed and qualified for such use.

13. NEVER modify this device or its accessories, except as instructed in the Service Manual,

Engineering Bulletins or formal communication as this may invalidate any warranty,

guarantee or type approval.

14. AVOID placing the transceiver in excessively dusty environments.

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Page 3 of 38

Service Manual SD170EX Series

Contents

Amendment Record Sheet............................................................................................................ 2

Warnings ..................................................................................................................................... 3

Contents ...................................................................................................................................... 4

Introduction ................................................................................................................................. 5

Pre-Install check, Accessories & Options ...................................................................................... 6

Pre-Installation ......................................................................................................................... 6

Accessories ............................................................................................................................. 6

etc ........................................................................................................................................... 6

Product Introduction .................................................................................................................... 7

Installation ................................................................................................................................... 8

Installation ............................................................................................................................... 8

External Connections ............................................................................................................... 8

General Specification.................................................................................................................... 9

Transmitter Specification ............................................................................................................ 10

Receiver Specification ................................................................................................................ 11

Reference Crystal ....................................................................................................................... 12

Enviromental.............................................................................................................................. 12

Dimensions ................................................................................................................................ 12

Features .................................................................................................................................... 13

Access to digital and RF boards .................................................................................................. 16

Alignment .................................................................................................................................. 19

Alignment points ........................................................................................................................ 23

Flow Diagrams ........................................................................................................................... 24

CTCSS ....................................................................................................................................... 26

Interfacing ................................................................................................................................. 27

External connections .............................................................................................................. 27

DB-9 PIN descriptions with input/output level.......................................................................... 27

Channel Selection ...................................................................................................................... 29

SD170EX Layouts Control Board ................................................................................................. 30

SD171EX Layouts RF Board ........................................................................................................ 34

SD174EX Layouts RF Board ........................................................................................................ 34

SD170EX control schematic ...................................................................................................... 34

SD171EX RF schematic ............................................................................................................ 34

SD174EX RX schematic ............................................................................................................ 34

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Page 4 of 38

Service Manual SD170EX Series

Introduction

This Maxon Product Manual is a comprehensive guide to the maintenance and field repair of this

equipment. It covers all versions of the SD170EX Series data radio(s). Before using this manual

please read the whole of this introductory chapter, this will help you to make the best use of it. If

you have not done so already, please also read the warnings immediately in front of this chapter

before proceeding any further.

Using this Manual

The organization of this manual has been arranged to enable the location and referencing of

information, as quickly as possible.

Section 3 - Installation, Commissioning & Alignment. Describes connections to the radio, how to

commission it and how to align the radio should this becomes necessary.

Section 4 - Detailed functional description.

Section 5 - Troubleshooting.

Amendments to this Manual

From time to time during its lifetime, this product will be updated and improved. To cover such

changes, amendments to this manual will be issued in the form of replacements and/or additional

pages. It is important that anyone working on a product has all the relevant information. Therefore

you should incorporate amendments to this manual on receipt. Please follow the instructions

accompanying the amendment (in the form of an Engineering Bulletin) and be sure to complete

the amendment record at the front of this manual.

On occasion it may be necessary to issue product information more quickly than can be achieved

with an amendment. In this case the information will be distributed as a Maxon Engineering

Bulletin. Engineering Bulletin numbers are prefixed with a category letter – A, B or C.

E.g. CATEGORY C – ENGINEERING BULLETIN 120

Category C describes how Maxon recommends an improvement and/or a modification to make an

improvement to a product

Engineering Bulletin 120 index number allocated to this bulletin.

‘A’ Category A Engineering Bulletins will only be released if, by using the equipment

manufactured by Maxon or its subcontractors, a risk to operator safety or an infringement of Type

Approval is probable.

All units affected should be returned for modification to Maxon CIC Europe Works Department on

receipt of such a Bulletin.

Page 5 of 38

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Service Manual SD170EX Series

‘B’ Category B Engineering Bulletins are for equipment manufactured by Maxon CIC that may

have component batch problems.

All equipment affected that is in service must be returned to the Distributor or Dealer workshop for

modification. Maxon CIC will supply replacement components free of charge.

‘C’ Category C Engineering Bulletins are for improvement or modification to equipment

manufactured by Maxon.

Dealer / Distributor to modify affected units in the field on the next service call. Maxon will supply

components free of charge.

Please place these at the back of this manual and refer to them before carrying out any work. This

Service Manual should be updated with any accompanying replacement pages. You may wish to

retain the previous issue pages for future reference.

Pre-Install check, Accessories & Options

Pre-Installation

As standard the SD-170EX Series Radio Modem is supplied with fused power Cable and
manual.

Accessories

The following Accessories are available:

Order Code Description
Antennas

CA1506-MB VHF Helical Antenna 148 - 160MHz
CA1506-HB VHF Helical Antenna 160 - 174MHz
CA4502 UHF Quarter-wave Whip Antenna 420 – 470MHz

Programmer

ACC-916 SD-170EX Series Programming kit Allows frequencies and

features to be changed.

Programming lead

Service

ACC-516E Extender PCB Allows RF PCB to be spaced off of the Digital

PCB to facilitate Alignment procedures.

V2 142-174MHz
U2 450-490MHz.

12.5 KHz or 25 KHz versions of all bands.

Page 6 of 38

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Service Manual SD170EX Series

Product Introduction

The SD-170EX Series (here in after called “the radios”) of RF wireless modems from MAXONCIC

utilize the latest technology in its design and manufacturing. Both the UHF and VHF models are

Phase Lock Loop Synthesizer (PLL) / microprocessor controlled and offer five watts of power with

16-channel capability. Programmable sub-audio squelch system (CTCSS & DCS) and two-tone

squelch system are newly added to the signal level detect squelch system (RSSI) through PC

Program. The radios are programmed using ACC 916 programming software, an Intel Pentium2

or higher Personal Computer, Operating system is Microsoft windows 98, ME, 2000, and XP and

Vista based software, an interface module and a programming cable. This allows the radio to be

tailored to meet the requirements of the individual user and of the System(s) it is operating within.

Antenna / RF connector

Programmer ACC 916

Page 7 of 38

BNC type nominal 50 impedance

XP, Vista, ME, 2000 and Windows based programmer
allowing personalization of the SD-170EX Series
Modems via the RS232 port.

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Service Manual SD170EX Series

Installation

Installation

The SD-170EX Series Radio Modems usually requires mounting in a suitable location.
Attention should be given to the heat sinking of the radio if prolonged transmission is
required; see Section 2, which also includes details of the mounting hole dimensions.

Note: Continuous transmission is not possible at high power (5W) without a suitable heat
sink.

The SD-170EX Series Radio Modems can be used with helical or whip aerials or may be
connected to an external antenna, via a suitable connecting cable.

External Connections

Connection is made to the SD-170EX Series Radio Modems via an external 50 ohm BNC
socket (RF signal) and a high density 9-way “D”-type socket (DB-9 connector; control and
data signals) with 4-40 UNC threaded jack posts for more permanent connection. Besides,
SCN-12 type circular connector is added to separate power line from data and analogue
signals of DB-9 connector.

Page 8 of 38

Service Manual SD170EX Series

VHF

UHF

General Specification

Equipment Type

Model Series

Performance

Specifications

Frequency Range

RF Output

Channel Spacing

Modulation Type

Intermediate

Frequency

Number of Channels

Frequency Source

Operation Rating

Power Supply

Temperature Range

Storage

Operating

Data radio (Wireless Modem)

SD-171EX SD-174EX

TIA/EIA-603 /ETS 300-113 TIA/EIA-603 /ETS 300-113

142-174MHz 450-490MHz

1-5W 1-5W

12.5KHz, 25KHz Programmable

45.1MHz & 455KHz

Synthesizer

Intermittent

90 : 5 : 5 (Standby : RX : TX)

Ext. Power Supply (12 VDC Nominal)

From -40°C to +80°C
From -30°C to +60°C

Data radio (Wireless Modem)

F3D, F3E

16

Current Consumption

Standby(Muted)

Transmit 5Watts RF

Power

Transmit 2Watts RF

Power

Lock Time

TX to RX attack time

RX to TX attack time

Dimensions

Weight

Page 9 of 38

< 65mA

< 2.0 A
< 1.0 A

< 10ms

< 20ms (No Power Saving)

< 20ms

(118mm)W X (63mm)H X (35mm)D

266.5grams

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Service Manual SD170EX Series

VHF

UHF

Carrier

Power (

Nom. Max.

Low Power

Sustained Transmission

(Nominal Conditions)

Frequency Error

Transmitter Specification

Model Series

Min.)

Hi Power

Time : 5 10 30 Sec

Nominal condition
Extreme condition

Frequency Deviation

25 KHz Channel Spacing

12.5 KHz Channel Spacing

Audio Frequency

Response

Adjacent Channel Power

25 KHz Channel Spacing

12.5 KHz Channel Spacing

Conducted Spurious

Emission

Modulation Sensitivity

Hum & Noise

25 KHz Channel Spacing

12.5 KHz Channel Spacing

SD-171EX SD-174EX

5W < 6W > 4.5W

1W<1.5W>0.8W

Power : >90% >85% >80%

< 0.5 KHz ±2.5 ppm

Peak ±5.0, Min. ±3.8KHz
Peak ±2.5, Min. ±1.9KHz

Within +1/-3dB of 6dB octave

@ 300 Hz to 2.55 kHz for 12.5 kHz C.S.

@ 300 Hz to 3.0 kHz for 25 kHz C.S.

< 70 dBc @ Nominal Condition , < 65 dBc @ Extreme Condition
< 60 dBc @ Nominal Condition , < 55 dBc @ Extreme Condition

< -36 dBm < -36 dBm

100mV RMS @ 60% Peak Dev.

> 40 dB (without PSOPH)

> 40 dB (with PSOPH)

5W < 6W > 4.5W

1W<1.5W>0.8W

Power : >90% >85% >80%

< 0.75 KHz ±2.5 ppm

Modulation Symmetry

Load Stability

Peak Deviation Range

Adjustment

@ 1 KHz, Nom Dev +

20dB :

25 KHz Channel Spacing

12.5 KHz Channel Spacing

Page 10 of 38

< 10% Peak Dev @ 1KHz input for nominal dev. + 20dB

No osc at ≥ 10:1 VSWR all phase angles and suitable antenna

No destroy at ≥ 20:1 all phase angle

Min. 3.5, Max. 6.0
Min. 1.5, Max. 4.0

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Service Manual SD170EX Series

VHF

UHF

Sensitivity (

1/100 Error Rate

)

With ACC

-

514

< -110dBm

< -110dBm

Conducted Spurious Emission

Receiver Specification

Model Series

Sensitivity (@ 12dB SINAD)

25 KHz Channel Spacing

12.5 KHz Channel Spacing

With ACC-513

Amplitude Characteristic > -3dB , < +3dB > -3dB , < +3dB

Adjacent Channel Selectivity

25 KHz Channel Spacing(Nom.)

(Extreme Condition)

12.5 KHz Channel Spacing(Nom.)
(Extreme Condition)

Spurious Rejection(100KHz ~ 4GHz) > 70 dB > 70 dB

Image / Half IF Rejection > 70 dB > 70 dB

Intermodulation Response Rejection

±25 kHz/ 50 kHz

±50 kHz/ 100 kHz

9 KHz - 1 GHz

1 GHz – 4 GHz

SD-171EX SD-174EX

< 0.28uV
< 0.30uV

< -113dBm

> 70 dB
> 60 dB
> 65 dB
> 50 dB

> 70 dB
> 70 dB

< - 57 dBm
< - 47 dBm

< 0.28uV
< 0.30uV

< -113dBm

> 70 dB
> 60 dB
> 65 dB
> 50 dB

> 70 dB
> 70 dB

< - 57 dBm
< - 47 dBm

RX Spurious Emissions (Radiated)

9 KHz - 1 GHz

1 GHz – 4 GHz

AF Distortion :
Nominal condition
Extreme condition

RX Hum & Noise (only audio)

25 KHz Channel Spacing

12.5 KHz Channel Spacing

Receiver Response Time

Squelch (factory pre-set)

Open

Close

Squelch Attack Time :

RF Level at Threshold

RF Level at Threshold + 20dB

Squelch Decay Time

Antenna Socket Input Match

Temperature Stability for

L.O. Frequency

L.O. Frequency Aging Rate

Page 11 of 38

< - 57 dBm
< - 47 dBm

< 3%

< 10%

< 40 dB without PSOPH

< 16 ms < 16 ms

-113dBm

-116dBm

< 20 ms (RSSI), < 40 ms (Analog)
< 10 ms (RSSI), < 30 ms (Analog)

5 ms Min., 20ms Max.

> 10 dB Return Loss

1st < 5 ppm, 2nd < 15 ppm from -30° to + 60° C

±2 ppm/ year

< 40 dB with PSOPH

< - 57 dBm
< - 47 dBm

< 3%

< 10%

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Service Manual SD170EX Series

Temperature

Model Series :

Temperature (deg C)

Reference Crystal

Model Series

Frequency

Type

Characteristic

Aging Rate

Enviromental

Operating

Storage

ESD

 Due to continuing research and development the company reserves the right to alter

these specifications without prior notice.

Dimensions

Dimensions: 122mm (L) x 62mm (W) x 35mm (D)

-30° to +60° C Degradation Specified @ Extreme condition

VHF UHF

SD-171EX

12.8MHz

DV-5-2.5H1

±2.5 ppm from -30° C to +60° C

< 2 ppm/ year in 1st year

< 1 ppm/ year thereafter

VHF

SD-171EX SD-174EX

-40° to +80° C
20 KV

SD-174EX

UHF

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Page 12 of 38

Fig 3. Dimensions

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Service Manual SD170EX Series

Features

16 Channels

The SD-170EX Series radio can store up to 16 channels within the same band. These channels

can be selected by inner DIP-S/W or serial command inputted from external control system.

Channel Spacing

The SD-170EX Series is capable of programmable channel spacing, in both UHF and VHF bands.

Each channel can be programmed via the PC programmer, ACC-916, having 12.5KHz or 25KHz

channel spacing.

Output Power

In case of SD-170EX Series, it’s programmable. Each channel can be programmed via the PC

programmer to a high-power output, 5 Watts, and a low-power output, 1 Watt.

Channel Scan

For audio application, SD-170EX Series supports channel scan enabled via serial commands.

During programming of the radio, any channel can be selected as a scanned channel. When a

scanned channel is selected, it becomes a part of the scan list. Once the scan list has been

established, initiates scan by serial commands. If a conversation is detected on any of the

channels in the scan list, the radio will stop on that channel and audio signal will be released

through pin 9 of the DB-9 connector. At that moment, busy channel data is sent to external

equipment or device through serial command. So, busy channel data can be identified as

decoding received serial command from radio in the external equipment or device. Normally, if

user tries to transmit during scanning, the transmission will be made on the channel that the call is

received during the programmable scan delay time. (The scan delay time is the amount of time

the radio will stay on that channel once working has ceased. Dealer programming of 4 ~ 7

seconds is typical). The radio will resume scanning once the scan delay time has passed, and will

continue to scan until the serial command for scan stop is inputted by external equipment. After

the scan has resumed, if a transmission is made, the radio will transmit on the selected priority

channel. This feature is similar to priority scan TX except for selection of priority channel. You can

assign a priority channel by inner dip switch only.

Scan Delete

To temporarily delete a channel from the scan list, simply input the serial command for scan

deletion to the radio while scanning and stopped on the channel to be deleted. This will

temporarily remove that channel from the scan list until the scan is closed or the radio’s power is

reset.

Page 13 of 38

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Service Manual SD170EX Series

CTCSS / DCS Scanning

To help to block out unwanted calls to your radio, the SD170E series can be programmed by your

dealer to scan for tones.

Busy Channel Lockout

This feature, when enabled, disables the transmitter when the user would attempt to transmit

during the receiving channel is busy. It will be dealer-programmable on/off and applicable to all

channels.

Marked Idle

When used in conjunction with Busy Channel, lockouted transmitter is allowed to operate as long

as valid RX tone is received. Dealers program this feature as ON or OFF. This feature will be

dealer-programmable on/off and applicable to all channels.

TX Time-out

This feature, when enabled, limits the amount of time that the user can continuously transmit. This

time can be set in increments by 10 seconds from 10 seconds to 990 seconds. If the user

attempts to transmit longer than the TX Time-out period, five seconds prior to expiration, the radio

will release Time-out alert signal through pin 9 of the DB-15 connector and will cease

transmission.

Power Save

The function of Power Save is used when an external battery is used as the power source. When

Power Save is enabled, the receiver ON and OFF time can be programmed and allows the

operator to set the length of time the receiver gets asleep.

TX Delay

The TX will remain active for 150 ms at the end of TX when using CTCSS tones. This eliminates

squelch tail. Dealer programs this feature as ON or OFF.

Squelch Options

Compared to existing Maxon data radios, programmable sub-audio squelch system (CTCSS &

DCS) and two-tone squelch system are newly added. Each channel will have these squelch

option sets during dealer programming. More detail descriptions for all available squelch systems

of SD170EX are the following.

Page 14 of 38

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Service Manual SD170EX Series

Sub-audio squelch system

The SD-170EX Series can operate singly or with optional modem boards. Even if user wants to

use sub-audio SQ system, the radio will permit this SQ option according to some cases to avoid

confliction between sub-audio and data.

Contrary to general-purpose two-way radio, the input of the radio is data or audio. In case of audio,

its frequency spectra are limited to 300 ㎐ ∼ 3 ㎑ by internal BPF. So, the division of this and sub-

audio is possible on the frequency spectra because sub-audio has under 300 ㎐ frequency. But,

Data has wide frequency spectra compared with audio.

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Service Manual SD170EX Series

Access to digital and RF boards

Removing top cover

Disassembly and Re-assembly of the Radio

In order to carry out the following Test and
Alignment procedures it will be necessary to
gain access to the inside of the radio.

Care should be exercised when opening up the
radio for maintenance or repair.

In order to

Disassemble the radio; the following procedure
should be used:

1. Unfasten and remove the four mounting

Removing the Digital board

screws located on the top cover of the radio.

2. Remove the four mounting screws located on
the top of the Digital board.

3. Gently lift Digital board away from the
connector on the RF board from the opposite
end to the D-type.

Page 16 of 38

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Service Manual SD170EX Series

Removing Screen

4. Remove the screen by carefully

desoldering the screen from the RF board

near to the BNC connector.

Page 17 of 38

5. Then lift screen out.

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Service Manual SD170EX Series

REMOVING & REPLACING THE RF BOARD

6. Unscrew the four holding screws from the
RF board.

7. De-solder the RF lead at the BNC
connection

Page 18 of 38

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Service Manual SD170EX Series

Alignment

Transmitter Alignment

Connect the unit to a Service Monitor with the power meter set to the 10 W scale (or auto range).
Refer to figure 4.4 under commissioning section

TCXO

Set the channel selector to the mid-range frequency 460MHz (U2) and 155MHz (V2), adjust
TCXO1 for a reading accurate to within ±200Hz.

TX VCO

TX VCO is pre-tuned at the factory and no further adjustment is required

To verify the alignment of the TX VCO, check the VCO Control voltage.

Set the unit to the highest transmit frequency, 480MHz (U2), 174MHz (V2). Key the
transmitter and verify that the VCO control voltage is under 10.0 Volts. If necessary adjust
C208 of TX VCO to 10.0 Volts.

Set the unit to the lowest transmit frequency 440 MHz(U2), 146(V2) key the transmitter and
verify that the VCO voltage is above 1.8 Volts. If necessary adjust C208 to 1.8 Volts.

Note: use TP1 to measure the voltage.

Deviation

CTCSS and DCS Deviation and Balance Adjustment

Set the unit to a mid-frequency range and a CTCSS of 67Hz. Activate PTT and adjust RV402

(deviation adjustment) for desired CTCSS tone deviation.

Switch to a channel with the same frequency and CTCSS of 250.3Hz. Activate PTT and adjust

RV1 (balance adjustment) to desired CTCSS tone deviation, same as above step.

Switch between the 67Hz channel and the 250.3Hz channel and adjust RV1 until the deviation

is the same on both channels. It may be necessary to readjust RV402 to get the desired
deviation.

Audio balance and deviation adjustment

Set the unit to a mid-frequency and input the TX data with 400 Hz standard audio level
(100mV for data or 10mV for audio in). Increase the signal level to 20 dB from standard
level.

Monitor the demodulated signal from service monitor. Adjust RV1 to make the monitored
signal to be a balanced square wave.

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Sweep the audio frequency from 300 Hz to 4 kHz and ensure that the peak deviation does
not exceed the limits shown below. If necessary adjust RV2 to vary audio deviation.

12.5 kHz channel spacing <= 2.5 kHz dev.

20 kHz channel spacing <= 4 kHz dev.

25 kHz channel spacing <= 5 kHz dev.

Note: When using one of the internal modems (ACC-513 or ACC-514) a test signal needs to be
applied to the radio (e.g. data from the computer). The deviation levels should not exceed the
limits as shown above.

APC (output power)

When using the extender board (ACC-516) there is a voltage drop in transmission mode
and so output power drops. As a result the radio outputs higher power than assigned
after assembly. To prevent over-power output, follow below procedure

Adjust RV4 to set high power at the point of 4.6W.

Adjust RV3 to set low power at 0.6W

Assemble the radio and again check if RF transmission power is near 5.0W for high
power and 1W for low power.

RECEIVER

Refer to figure 4.5 in the Commissioning section for details on test equipment connection

RX VCO

RX VCO is pre-tuned at the factory and adjustment should not be required

To verify the adjustment of the RX VCO, check the VCO Control voltage.

Set the unit to the highest receiving frequency, 480MHz (U2), 174MHz (V2) and verify the
VCO control voltage is under 10.0 Volts. If necessary adjust C308 of RX VCO to 10.0 Volts

Set the unit to the lowest receive frequency 440MHz (U2), 146(V2) and verify that the VCO
voltage is above 2.0 Volts. If necessary adjust C308 to 2.0 Volts.

Note: Use TP1 to measure the voltage.

AUDIO OUTPUT LEVEL Adjustment

Set the RF signal generator to the receiver frequency of the radio and set the AF modulation

signal to 1 kHz with the following deviations depending on channel spacing:

1.5 kHz deviation for 12.5 kHz channel spacing

2.4 kHz deviation for 20 kHz channel spacing

3 kHz deviation for 25 kHz channel spacing

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Adjust the RF output level of the RF signal generator to –47dBm and connect to the radio.

Monitor the output on the audio output pin and adjust RV401 for the specific audio output
level.

Squelch Adjustment

Before squelch adjustment is made the squelch type should be selected via software. Squelch
level to open or close (un-mute or mute) is set up by not only software control but also hardware
control and programmed by the system option of the ACC-916 programming software.

Squelch Adjustment (Noise SQ only)

Select a receiver channel which is programmed for narrow band (12.5 kHz) operation. Set the
RF signal generator to the receiver frequency and set the AF modulation signal to 1 kHz at

1.5kH deviation.

Adjust the RF output level of the RF signal generator until the 1 kHz signal is heard. Adjust
the RF signal to the desired level for squelch sensitivity as you monitor SINAD, usually 8 to 12
dB. On the RF board, adjust RV5 until the squelch is just un-muted (open).

Switch off the RF generator (squelch should be closed).

Switch on the RF generator, Squelch should be opened at the SINAD point where RV5 was

adjusted.

Select a receiver channel that is programmed for wide band operation (25kHz). Set the RF
signal generator to the receiver frequency and the AF modulation signal to 1 kHz at 3kH
deviation.

Adjust the RF output level of the RF signal generator until the 1kHz signal is heard, and then
adjust the RF signal to the desired level for squelch sensitivity as you monitor SINAD, usually
8 to 12 dB. On the RF board, adjust RV6 until the squelch is just un-muted (open).

Switch off the RF generator (squelch should be closed).
Switch on the RF generator, Squelch should be opened at the SINAD point where RV6 was

adjusted.

Disconnect the test equipment.

Squelch Adjustment (RSSI SQ only) using ACC-2016 & ACC-916

Default setting of squelch level for all radios is approximately set at:

Squelch open (un-mute) at -114 to -113dBm (0.45 - 0.5mV of the RX signal strength)

Squelch close (mute) at -117 to -116dBm (0.3 - 0.35mV of the RX signal strength)

Changing the default squelch settings requires use of the programming cable and software.
Those are designed for use not only as part of the programming kit but also as a tool of squelch
level setting.

Still using the same connections for the receiver performance test, run the programmer ACC-

916 on the PC and select calibration mode. Select “Custom Define” menu of Squelch program
menu of ACC-916.

Adjust the RF signal generator for the desired signal strength to OPEN squelch (e.g. default
setting is approximately –113dBm, equivalent to 0.5mV)

Press “Set(OPEN)” button, LED indicator will flash 3 times then it will be ON.

Adjust the RF signal generator for the desired signal strength to CLOSE squelch (e.g. default
setting is approximately -116dBm, equivalent to 0.35mV). Press “Set(CLOSE)” button, LED
indicator will flash 2 times then it will be OFF.

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Press “SAVE” button, LED indicator will flash once.

Squelch level is now set. Test for the desired level by increasing or decreasing the RF signal to
levels set for open and close squelch (mute LED will be OFF & un-mute LED will be ON).

Brief block signal flow diagrams for each input are the following (See Figure 3.1. ~ 3.3.).

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Alignment points

Alignment Points Diagrams

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Flow Diagrams

Flow Diagrams

Audio Amp. & Filter

Z0
Z1

Y0
Y1

X0
X1

Analog S/W

MC14053B

Sub-Audio

Encoder

Z

Y

X

Pre-emphasis

MCU

300Hz HPF

MF6

Sub-Audio LPF

Check Audio In

Tone En

High : Audio In
Low : No Audio

Data BPF

Adj. Level

Level

Detector

Audio signal flow in Transmitter

Audio In

Mod Out

RF Board

RSSI

AF

Busy

IF IC

SA605DK

Mute

Audio

LM386

Audio Amp.

4th Order

Sub-Audio LPF

MF6

Comparator

Audio Out

Pre-Selector

Z0

Z

Z1

Y0
Y1

X0
X1

Analog S/W

MC14053B

300Hz HPF

Y

X

MF6

Sub-Audio LPF

Audio Mute

RSSI

MCU

Tone Detector

Audio signal flow in Receiver

High : Audio In
Low : No Audio

Z0

Z

Z1

Y0

Y

Y1

X0

X

X1

Analog S/W

MC14053B

Sub-Audio

Encoder

Sub-Audio LPF

Check Audio In

MCU

MF6

Adj. Level

Tone En

Audio signal flow in Transmitter

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Audio signal flow diagram

Detector

Data BPF

Level

Audio In

Mod Out

RF Board

RSSI

AF

Busy

IF IC

SA605DK

Mute

Audio

LM386

Audio Amp.

4th Order

Sub-Audio LPF

MF6

Comparator

Pre-Selector

Z0
Z1

Y0
Y1

X0
X1

Analog S/W

MC14053B

Z

300Hz HPF

Y

X

MF6

Sub-Audio LPF

Audio Mute

RSSI

MCU

Tone Detector

Audio signal flow in Receiver

Audio Out

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Data signal flow diagram

RF Board

Level

Detector

High : Audio In
Low : No Audio

Z0

Z

Z1

Y0

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Y1

X0

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X1

Analog S/W

MC14053B

Sub-Audio

Encoder

Ext. Mod. signal flow in Transmitter

Sub-Audio LPF

Data Enable

Check Audio In

MCU

MF6

Tone En

Data BPF

Adj. Level

External modulated signal flow diagram

Data In

Audio In

Mod Out

RSSI

AF

Busy

IF IC

SA605DK

4th Order

Sub-Audio LPF

MF6Tone Detector

Comparator

Pre-Selector

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Y1

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X1

Analog S/W

MC14053B

Ext. Mod. signal flow in Receiver

30Hz ~ 5KHz

BPF

MF6

Sub-Audio LPF

RSSI

MCU

Audio Out

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CTCSS

CTCSS signal information

Each channel supports the 38 TIA/EIA standard tone frequencies and 11 non-standard tones.

All tones will be set up during dealer programming.

No.

01 67.0 11 97.4 21 136.5 31 192.8 41 171.3
02 71.9 12 100.0 22 141.3 32 203.5 42 177.3
03 74.4 13 103.5 23 146.2 33 210.7 43 183.5
04 77.0 14 107.2 24 151.4 34 218.1 44 189.9
05 79.7 15 110.9 25 156.7 35 225.7 45 196.6
06 82.5 16 114.8 26 162.2 36 233.6 46 199.5
07 85.4 17 118.8 27 167.9 37 241.8 47 206.5
08 88.5 18 123.0 28 173.8 38 250.3 48 229.1
09 91.5 19 127.3 29 179.9 39 69.3 49 254.1
10 94.8 20 131.8 30 186.2 40 159.8

DCS signal information

The radio supports the encoding and decoding of 104 DCS data (include TIA/EIA code).

Octal
Code

023 054 125 165 245 274 356 445 506 627 732
025 065 131 172 246 306 364 446 516 631 734
026 071 132 174 251 311 365 452 523 632 743
031 072 134 205 252 315 371 454 526 654 754
032 073 143 212 255 325 411 455 532 662
036 074 145 223 261 331 412 462 546 664
043 114 152 225 263 332 413 464 565 703
047 115 155 226 265 343 423 465 606 712
051 116 156 243 266 346 431 466 612 723
053 122 162 244 271 351 432 503 624 731

Freq.

(Hz)

Octal
Code

No.

Octal

Code

Freq.

(Hz)

CTCSS Frequency Chart

Octal

Code

Octal
Code

No.

Octal
Code

Freq.

(Hz)

Octal
Code

No.

Octal
Code

Freq.

(Hz)

Octal
Code

No.

Octal
Code

Freq.

(Hz)

Octal
Code

DCS Code Chart

Two-Tone Squelch (SQ) System

The radios will support Motorola-Format, Two-Tone (Type 99) decoding. This is receive only,
decode only feature. It will allow a dispatcher to call individuals and groups. Each System/Group

will be programmable to respond to any combination of the code, with a distinctive alert for each
System/Group. The alert format consists of two tone sequences, first the ID of the radio being
called, then the ID of the calling radio.

This feature is programmed by the dealer (per customer’s request) and is not activated /
deactivated by the user. The user interface consists of the radio emitting the tones being
broadcast. At this point, the radio will enter Unmuted Rx mode and remain in this mode until the
PTT signal is inputted.

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Service Manual SD170EX Series

D - Type

Input/

Interfacing

External connections

Connection is made to the SD170EX via an external 50 ohm BNC socket (RF signal) and a high
density 9-way “D”-type socket (DB-9 connector; control and data signals) with 4-40 UNC threaded
jack posts for more permanent connection. Besides,

DB-9 Pin includes “Power”. The data communication during PC program is used through one pin
so that the application design should be considered for the pin when you use the applied circuit
which is made on your way.

DB- 9 PIN descriptions with input/output level

Pin No.

1

2

3

4
5 Power Power connection to Out of the radio. DC +12V

6

7

8

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Function Description Signal Type

Analog signal

Data modulation
IN
(TX Mod)

Data unfiltered
OUT
(RX disc)

PTT In
(TX Key)

Ground. Ground.

Serial Data Out

Microphone
filtered audio IN

Serial data
IN/OUT

Speaker filtered
OUT

Signal is directly injected to MOD
through data low pass filter without
pre-emphasis.

Discriminator audio from the SD-160.
This is the unprocessed AF signal
prior to tone filtering and de­emphasis.

Signal from the ‘external device’ to
key the SD-160 transmitter.
This line has an internal pull up
resistor to +5V. Pulling the line to 0V
turns on the transmitter.

Note: If you installed option
modem board, you can select RS­232 signal level by Jumper
(CON407) on the digital board. See
Figure 8.2.

Serial data output for radio control or
program. It uses asynchronous data
format.

This signal is injected to the MOD at
the point through audio-amplification,
pre-emphasis and high pass filtering
where sub-audio tone is mixed with
audio.

Serial command or data input and
data output for radio control or
program. It uses asynchronous data
format.

Audio output from the audio
amplifier.
It’s filtered by tone-filter, de­emphasis circuit.

1KHz audio at 60%
peak system
deviation
input level =
100 to 120mVrms
Analog signal
1KHz audio at 60%
peak system
deviation produces
200 to 300mVrms

TTL level
0V = Tx
o/c = Rx

RS-232 level
(option)
+12V = Tx

-12V = Rx

DC 0V

TTL level O/P

Audio
1KHz audio at 60%
peak system
deviation
input level =
6 to 8Vrms

TTL level I/O/P

Audio
1KHz audio at 60%
peak system
deviation produces
Nominal 1Vrms @
8Ω

Output

I/P

O/P

I/P

I/P

I/P

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Channel Selection

Setting of channel selector switch for each channel

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SD170EX Layouts Control Board

Control Board top Reference

L

L

Control Board bottom Reference

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SD171EX Layouts RF Board

RF Board top reference RF Board top reference

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RF Board bottom Reference

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SD174EX Layouts RF Board

RF Board top reference RF Board top reference

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RF Board bottom Reference

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SD170EX Control Schematic

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SD171EX RF Schematic

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SD174EX RF Schematic

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