Maxon SD-125E Service Manual
SD-125E
SERVICE
MANUAL
MaxonCIC Corp. Chongho Bldg, #7-61, Yangjae-Dong, Seocho-Ku, Seoul, 137-130, Korea
Phone: (82) 2 3498 - 3114; Fax: (82) 2 3498 -3113
October 2008
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SD-125E RF LINK MODULE
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1. TABLE OF CONTENTS
2
2. SPECIFICATIONS
4
3. UNPACKING
8
4. INTRODUCTION
9
5. FEATURES
10
6. THEORY OF OPERATION
11
6.1 INTRODUCTION 11
6.2 DIGITAL CIRCUITS 11
6.3 RF CIRCUITS 12
6.4 RF CIRCUITS PLL SYNTHESIZER 13
6.5 RECEIVER 14
7. MAINTENANCE AND REPAIR 16
7.1 GENERAL 16
7.2 REMOVING & REPLACING THE UPPER COVER 16
7.3 REMOVING & REPLACING THE DIGITALBOARD & SHIELD PLATE 17
7.4 REMOVING & REPLACING THE RF BOARD 18
8. PROGRAMMING 20
9. ALIGNMENT PROCEDURE 20
9.1 RECEIVER 20
9.2 TRANSMITTER 20
10. TEST EQUIPMENT SETUP 23
11. ALIGNMENT POINTS DIAGRAM 24
12. COMPONENT REPLACEMENT 25
13. TROUBLESHOOTING GUIDE 27
14. WIRING DIAGRAM 28
15. COMPONENT PINOUT 29
17. SCHEMATICS, BLOCK DIAGRAM & PCB’s 32
17.1 BLOCK DIAGRAM
17.2 RF BOARD(400-430MHz)SCHEMATIC
17.3 DIGITAL BOARD(400-430MHz)SCHEMATIC
17.4 RF BOARD(440-470MHz)SCHEMATIC
17.5 DIGITAL BOARD(440-470MHz)SCHEMATIC
17.6 RF BOARD(470-490MHz)SCHEMATIC
17.7 DIGITAL BOARD(470-490MHz)SCHEMATIC
17.8 RF BOARD(148-174MHz)SCHEMATIC
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17.9 DIGITAL BOARD(148-174MHz)SCHEMATIC
17.10 RF BOARD VHF PRINTED CIRCUIT BOARDS
17.11 RF BOARD UHF PRINTED CIRCUIT BOARDS
17.12 DIGITAL BOARD PRINTED CIRCUIT BOARDS
18. EXPLODED VIEW & PARTS LIST
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GENERAL
Equipment Type ……………………………………………………… Data radio
Performance Specifications………………………………………… TIA/EIA -603 / IC, RSS212
Band …………………………………………………………………… VHF(SD-125VEV2) / UHF(SD-125VEU)
Channel Spacings …………………………………………………… 25 kHz, 12.5 kHz programmable
RF Output Power …………………………………………………… 1 watt, 5 watt programmable
Modulation Type …………………………………………………… F3D, F3E
Intermediate Frequency …………………………………………… 45.1 MHz & 455 kHz
Number of Channels ………………………………………………… 16
Frequency Source …………………………………………………… Synthesizer
Operation Rating …………………………………………………… Intermittent
90 : 5 : 5 (Standby: RX: TX)
Power Supply ………………………………………………………… Ext. Power Supply(12 VDC Nominal)
9.0V - 15.0V DC EXTREME
Temperature Range
Storage ………………………………………………………………… from - 40°C to + 80°C
Operating ……………………………………………………………… from - 30°C to + 60°C
Current Consumption
Standby (Muted) ……………………………………………………… < 65 mA
Transmit 5 Watt RF power ………………………………………… < 2.0 A
Transmit 1 Watt RF power ………………………………………… < 1.0 A
Frequency Bands:
RX TX
VHF : V1 136.000 – 162.000MHz 136.000 – 162.000 MHz
V2 148.000 - 174.000 MHz 148.000 - 174.000 MHz
UHF : U1 400.000 - 430.000 MHz 400.000 - 430.000 MHz
U2 440.000 - 470.000 MHz 440.000 - 470.000 MHz
U3 470.000 - 490.000 MHz 470.000 - 490.000 MHz
U4 490.000 – 512.000 MHz 490.000 – 512.000 MHz
U5 420.000 – 450.000 MHz 420.000 – 450.000 MHz
Lock Time ……………………………………………………………… < 10 mS
TX to RX attack time ………………………………………………… < 20 mS (No Power Saving)
RX to TX attack time ………………………………………………… < 20 mS
Dimensions…………………………………………………………… (30mm)H x (62mm)W x (118mm)D
Weight ………………………………………………………………… 242grams
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TRANSMITTER Specification
Carrier Power: ………………………………………………………… Nom. Max. Min.
Hi ………………………………………………………………………5W < 6W > 4.5W
Low ……………………………………………………………………1W < 1.5W > 0.8W
Sustained Transmission …………………………………………… Nominal conditions
Time : 5 10 30 Sec.
Power: >90% >85% >80%
Frequency Error ………………………………………………………< 0.5 kHz Nominal condition for VHF
< 0.75 kHz Nominal condition for UHF
±3.0 ppm Extreme condition for UHF
±5.0 ppm Extreme condition for VHF
Frequency Deviation:
25 kHz Channel Spacing…………………………………………… Peak ±5.0, Min. ±3.8
12.5 kHz Channel Spacing………………………………………… Peak ±2.5, Min. ±1.9
Audio Frequency Response………………………………………… 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.
Adjacent Channel Power
25 kHz ………………………………………………………………… < 70 dBc @ Nominal Condition
< 65 dBc @ Extreme Condition
12.5 kHz ……………………………………………………………… < 60 dBc @ Nominal Condition
< 55 dBc @ Extreme Condition
Conducted Spurious Emission …………………………………… < -57dBc
Modulation Sensitivity ……………………………………………… 100mV RMS @ 60 % Peak Dev.
Hum & Noise:
25 kHz Channel Spacing …………………………………………… > 40 dB (with no PSOPH)
12.5 kHz Channel Spacing ………………………………………… > 40 dB (with PSOPH)
Modulation Symmetry ……………………………………………… < 10 % Peak Dev @ 1 kHz input
for nominal dev +20dB
Load Stability ………………………………………………………… No osc at ≥ 10:1 VSWR all phase angles and suitable antenna
No destroy at ≥ 20:1 all phase angle
Peak Deviation Range Adjustment @ 1 kHz, Nom. Dev +20dB:
25 kHz Channel Spacing …………………………………………… Min. 3.5, Max. 6.0
12.5 kHz Channel Spacing ………………………………………… Min. 1.5, Max. 4.0
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RECEIVER Specification
Sensitivity (12dB Sinad) …………………………………………… Standard B.W < -117 dBm, Narrow B.W <-118 dBm
@ Nom. Condition
Standard B.W < -115 dBm, Narrow B.W <-116 dBm
@ Extreme Condition
Amplitude Characteristic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < ±3 dB
Adjacent Channel Selectivity:
25 kHz Channel Spacing …………………………………………… > 70 dB @ Nom., > 60 dB @ Extreme Condition
12.5 kHz Channel Spacing ………………………………………… > 60 dB @ Nom., > 50 dB @ Extreme Condition
Spurious Response Rejection …………………………………… > 70 dB (100 kHz - 4 GHz)
Image Response ……………………………………………………… > 60 dB
IF Response…………………………………………………………… > 70 dB
Others. ………………………………………………………………… > 70 dB
Intermodulation Response Rejection:
±25 kHz/ 50 kHz ……………………………………………………… 65 dB
±50 kHz/ 100 kHz …………………………………………………… 65 dB
Conducted Spurious Emission @ Nominal Conditions:
9 kHz - 1 GHz ………………………………………………………… < -57 dBm
1 GHz - 4 GHz. ………………………………………………………… < -47 dBm
RX Spurious Emissions (Radiated) @ Nominal Conditions
9 kHz - 1 GHz ………………………………………………………… < -57 dBm
1 GHz - 12.75 GHz …………………………………………………… < -47 dBm
AF Distortion. ………………………………………………………… < 5% @ Nom., < 10 % @ Extreme condition
RX Hum & Noise:
25.0 kHz CP …………………………………………………………… < 40 dB No PSOPH
12.5 kHz CP …………………………………………………………… < 40 dB with PSOPH
Receiver Response Time …………………………………………… < 16 mS
Squelch Opening Range: …………………………………………… RF level for 6 to 14 dB Sinad
Squelch Closing Range (Hysteresis): …………………………… 0 - 6 dB Sinad @ Nominal Condition
Squelch Attack Time:
RF Level at Threshold ……………………………………………… < 40 mS
RF Level at Threshold + 20 dB …………………………………… < 30 mS
Squelch Decay Time ………………………………………………… 5 mS Min., 20 mS Max.
Antenna Socket Input Match ……………………………………… > 10 dB Return Loss
L.O. Frequency Temperature Stability …………………………… 1st < 5 ppm, 2nd < 15 ppm from -30° to + 60° C
L.O. Frequency Aging Rate ………………………………………… ±2 ppm/ year
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Environmental (performance without degradation unless stated)
Temperature…………………………………………………………deg C
Operating ……………………………………………………………-30℃ to +60℃ Degradation Specified @Extreme
Storage……………………………………………………………….-40℃ to +80℃
Recharging …………………………………………………………..-10℃ to+55 ℃
ESD ………………………………………………………………….. 20kV (C-MIC≥15KV)
Vibration ………………………………………………………………MIL STD 810 C Procedures Ⅰ,Ⅱ,Ⅴand IEC68 26
PROGRAMMER
Programmer ( Software) …………………………………………ACC-900E
Programmer ( Interface Cable) …………………
………………ACC-2125 (PC Program)
Programmer ( Interface Cable) …………………
………………TAJ-521D (SQ Program)
z Due to continuing research and development the company reserves the right to after these
specifications without prior notice.
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SD-125E RF LINK MODULE
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The SD-125 RF Link Module is the only item included in the shipping container.
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FCC RF Exposure Compliance Requirements.
The Federal Communications Commission (FCC), with its action in General Docket 93-62, November 7,
1997, has adopted a safety standard for human exposure to Radio Frequency (RF) electromagnetic energy
emitted by FCC requlated equipment. Maxon subscribes to the same safety standard for the use of its
products. Proper operation of this radio will result in user exposure far below the Occupational Safety and
Health Act (OSHA) and Federal Communications Commission limits.
Power listed is conducted. This device must not exceed a maximum transmitting duty factor of 50%. The
antenna(s) used for this transmitter must be installed to provide a separation distance of at least 60cm
(20inches) from all persons. Must not be co-located or operating in conjunction with any other antenna or
transmitter, and must not exceed a gain of 6 dBi. Failure to observe these restrictions will result in
exceeding the FCC RF exposure limits.
About your SD-125E Series Data Radio
The MaxonCIC SD-125E Series of RF Link Modules from MaxonCIC utilizes the latest technology in its
design and manufacturing. Both the UHF and VHF models are PLL (Phase Lock Loop Synthesizer) /
microprocessor controlled, and offer one to five watts of power with 16 channel capability. Multiple
functions including 1200 to 2400 baud rates, AC and/or DC audio coupling, FFSK and FSK modulation are
standard in these fully programmable wide bandwidth RF Link Module units.
The radios are programmed using an IBM
®
Personal Computer, DOS® or WINDOWS® 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.
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Busy Channel Lockout
16 Channels
TX Time-out
Power Save
1 / 5 Watt Programmable Output
12.5 / 25 kHz Programmable Channel Spacing
Busy Channel Lockout
The Busy Channel Lockout feature, when enabled, disables the transmitter when the receiving channel is
busy and the user attempts to transmit.
16 Channels
The SD-125 Series radio can store up to 16 channels within the same band.
TX Time-out
The TX Time-out feature, when enabled, limits the amount of time that the user can continuously transmit.
This time can be set in increments of 10 seconds from 10 seconds to 990 seconds.
Power Save
The Power Save feature 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 into the radio and allows the operator to set
the length of time the receiver is asleep.
.
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6.1 INTRODUCTION
The VHF and UHF radios are comprised of two PCB's (an RF PCB and a digital PCB). These boards are
connected with an 18 pin female and male connector . The digital board is interfaced with external data
equipment through the 9 pin d-sub male connector, which controls the radio and data receiving and sending .
6.2 DIGITAL CIRCUITS
The Digital circuit contains the CPU, the channel select switch, and associated digital circuits.
TX-SIGNAL CIRCUIT
The TX data signal comes from Pin 2 of Con 401, and goes through U404D. The TX-signal is amplified by
U406C. The TX-signal is filtered by U405A & B and U409A & B. which is a 4'th order low pass filter, the
output of U409A is then fed to the RF board for TX modulation.
RX-SIGNAL CIRC U IT
The RX-data signal comes from the RF board, which is connected with pin 10 of Con 403. The RX-signal is
switched by U404A and adjusted by RV403 and amplified by U407. The amplified signal goes to pin10 of
Con 401.
RSSI DETECTOR
From the RF board, the RSSI (Received Signal Strength Indicator ) signal flows to U403A & E through R461.
The pulse is injected from pin 5 of U403B every 1 mS and C451 is discharged. It is then charged by R464.
The RSSI signal is simultaneously input to pin 7 of U403A and those signals are compared. The compared
signal is output from U403A. Pin 1 of U403A and the CPU detects the pulse width. The pulse width is varied
by RSSI DC voltage, therefore, the carrier detection is controlled by the CPU.
EEPROM
RX / TX channel and RSSI detection level as well as other data from the programmer are stored in the
EEPROM. The data stored is retained without power supplied. This is a non-volatile memory. The EEPROM
may have information re-programmed or erased. U402 is an EEPROM with 2048 (8 x 256) capacity and data
is written and read serially.
CHANNEL SELECTOR
One of 16 channels may be selected using the Dip Switch (SW401). SW401 encodes the channel number,
selected into 4-bit binary code. The binary code plus one equals the channel number. The binary code is
decoded by the CPU enabling the appropriate RX or TX frequency and associated data to be selected from
the EEPROM.
DC TO DC CONVERTER
The main DC power is injected to the DC to DC converter . The DC to DC converter regulates the various
input power supply voltage and outputs a constant voltage of 7.5 Volts. It is a source for all of the RF and
digital circuits. The DC to DC converter is formed by IC801, Q801, Q802, L801 and R804. IC801 is a switch
mode DC to DC Converter IC. Input DC various appears as a voltage various through R804. IC801 detects
the voltage and controls the switching pulse. As the switching pulses, Q801and Q802 switches the input DC
of various supply voltages and generates the constant DC of supply voltage.
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6.3 RF CIRCUITS
TRANSMITTER
The transmitter is comprised of:
1 Buffer
2 P.A. Module
3 Low Pass Filter
4 Antenna Switch
5 A.P.C. Circuits
BUFFER
VCO output level is -6dBm and amplified to +10dBm (UHF), +6dBm (VHF). The buffer consists of Q8 and
Q9 for isolation and gain.
P.A. BLOCK
The P.A Block uses a three stage amplifier and contains Q701, Q702, and Q703. Three stage amplifier Q701
amplifies the TX signal from +10 dBm to 100 mW. Q702 is amplified to 0.5W. Q503 amplifies to 6W and then
matched to 50 Ohms using the L.C. network, thereby reducing the harmonics by -30 dB.
LOW PASS FILTER
L7, L8, L9, C36, C37, C38 and C39 are the 7th order Chebyshev low pass filter. Unwanted harmonics are
reduced by -70 dBc.
ANTENNA SWITCH
When transmitting, the diodes D3 and D5 are forward biased enabling the RF signal passage to the antenna.
D5 is shorted to ground inhibiting the RF signal to front end. In receive the diodes D5 is reversed biased
passing the signal from the antenna through L10 and C61 to the front end without signal loss.
AUTOMATIC CURRENT CONTROL (ACC) CIRCUITS
The ACC circuit consists of R63, variable resistor RV4, IC5(B) and transistors Q11 and Q12. The supply
current is monitored by the difference voltage on R63 (0.1 Ohm). If the current varies by RF power output or
other reasons, it produces some bias voltage by IC5A and Q15. The differential signal at the output of IC5(B)
is passed to Q11 and Q12 that produces a constant power output to the antenna. RV4 is used to adjust the
RF power level.
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6.4 RF CIRCUITS PLL SYNTHESIZER
12.8 MHz TCXO
The TCXO contains the 3-stage thermistor network compensation and crystal oscillator and modulation
ports. Compensation is ±5 PPM or less from -30c to +60c.
PLL IC DUAL MODULES PRESCALER
Input frequency of 12.8 MHz to Pin 1 of IC2 MB15E03SL is divided to 6.25 kHz or 5 kHz or 2.5KHz by the
reference counter, and then supplied to the comparator. RF signal input from VCO is divided to 1/64 at the
prescaler in IC2, divided by A and N counter in IC2 to determine frequency steps, and then supplied to the
comparator. PLL comparison frequency is 6.25/5/2.5kHz so that minimum programmable frequency step is
2.5/5/6.25 kHz. The A and N counter is programmed to obtain the desired frequency by serial data in the
CPU. In the comparator, the phase difference between reference and VCO signal is compared. When the
phase of the reference frequency is leading ,
ΦP is the output, but when VCO frequency is leading, ΦR is
the output. When
, ΦP= ΦR, phase detector out is a very small pulse.
EXTERNAL CHARGE PUMP
This is used to increase dynamic range of VCO. Voltage range is decided by the supply voltage of the
charge pump and the DC to DC converter which supplies that voltage. 0-12V is necessary for controlling the
VCO. In addition the radio adopts a current mode charge pump to take direct control of such parameters as
charge pump voltage swing, current magnitude, TRI-STATE leakage, and temperature compensation.
ΦP=
ΦR,
logic signals are converted into current pulses to enable either charging or discharging of the loop filter
components to control the output frequency of the PLL.
REFERENCE FREQUENCY LPF
The Loop Filter contains R9, C1 and C2. LPF settling time is 12mS with 1 kHz frequency. This also reduces
the residual side-band noise for the best signal-to-noise ratio.
DC TO DC CONVERTER
The DC to DC converter convert the 5v to 14-16v to supply the necessary voltage for wide range frequency
in the VCO.
VCO
The radio adopts a two VCO system for RX and TX in order to maximize each performance. The TX and RX
VCO generates RF carrier and local frequency and each VCO is switched by a TX/RX power source. It is
configured as a Colpitts oscillator and connected to the buffer as a cascade, the bias circuit is a cascade
configuration to save power. The varicap diode D201/D301 are low-resistance elements and have different
capacitance for reverse bias voltage. Using the change of reverse bias voltage (2~11V), the wanted
frequency for each channel can be obtained. L203/L303 are resonant coils and C208/C308 are used to
change the control voltage by the tuning core. D202 modulation diode modulates the audio signal. C204
compensates the non-linearity of the VCO due to the modulation diode and maintains a constant modulation
regardless of frequency.
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6.5 RECEIVER
FRONT-END
The receive signal is routed backward through the low pass filter, then onward to C601 of the Hybrid
Receiver Front End Module to a bandpass filter consisting of (VHF C622 through C608, L607 through L604 )
and (UHF C601through C610, L601 through L603 ) is coupled to the base of Q601 which serves as an RF
amplifier. Diode D601 serves as protection from static RF overload from nearby transmitters. The output of
Q601 is then coupled to a second bandpass filter consisting of (VHF C607 through C623 and L604 through
L607).The output of C623 is then coupled to the doubly balanced mixer Q16. The receiver front end module
is factory pre-tuned and requires no adjustment. Repair is effected by replacement of the entire module of
the proper banded module. These are VHF 148MHz to 174 MHz and UHF 400 MHz to 490 MHz. The
receiver front end module signal pins are as follows:
1 RF Input
2 Input Ground
3 N/A
4 Receive +5V
5 Ground
6 Output
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FIRST MIXER
Q16, L15 and C77 are Dual gate FET mixers which provide the 45.1 MHz intermediate frequency output.
The filtered frequency from the front end module is coupled to C131 The 45.1 MHz IF output is matched to
the input of the 2-pole monolithic filter by C65 and C66. The crystal filter provides a bandwidth of ±7.5 kHz
from the operating frequency providing a high degree of spurious and intermodulation protection. The IF
filter provides additional attenuation for the image frequency of the second mixer. The output impedance of
the filter is matched with the base of the post amplifier Q17 by C67 and C72
SECOND OSCILLATOR MIXER LIMITER AND FM DETECTOR
The output of the post filter amplifier, Q17, is coupled via C73 to the input of IC6(TA31136FN). IC6 is a
monolithic single conversion FM transceiver, containing a mixer, the second local oscillator, limiter and
quadrature detector. Crystal X1 44.645 MHz is used to provide resultant 455kHz signal from the output of
the
second mixer. The mixer output is then routed to CF1 (455F) or CF2 (455HT). These ceramic filters provide
the adjacent channel selectivity of 25 kHz or 12.5KHz bandwidth .
RSSI ( RECEIVER SIGNAL STRENGTH INDICATOR )
The RSSI signal is output from IC6 on pin 12. As the receiver signals the output, DC voltage is varied as
much as receiver signal strength. Also, the DC signal is temperature compensated with a thermistor (TH1).
would cause the CD (Carrier Detect) to act intermittently.
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7.1 GENERAL
When removing or fitting, use the Exploded View and Parts List, located on page 28 in conjunction with the
following procedures:
• WARNING: Disconnect the SD-125E from all external equipment at the D-Sub connector prior to
disassembly.
7.2 REMOVING & REPLACING THE UPPER COVER
Removing the Upper Cover:
1. Unscrew the four upper cover mounting screws located on the upper cover of the radio.
To replace the Upper Cover:
1. Reverse the steps taken to remove the Upper Cover.
Figure 1-Upper Cover Removal
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7.3 REMOVING & REPLACING THE DIGITAL BOARD & SHIELD PLATE
Removing the Digital Board Assembly & Shield Plate:
1 Remove the Upper Cover (refer to Removing & Replacing the Upper Cover).
2 Disconnect the DB9 pin connector on CON401.
3 Unscrew the 4 mounting screws.
4 Remove the Digital Board Assembly.
5 Remove the Shield Plate.
To replace the Digital Board Assembly:
1. Reverse the steps taken to remove the Digital Board Assembly & Shield Plate.
Figure 2-Digital Board Assembly Removal
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Figure 3-Shield Plate Removal
7.4 REMOVING & REPLACING THE RF BO ARD
Removing the RF Board Assembly:
1 Remove the Upper Cover (refer to Removing & Replacing the Upper Cover).
2 Remove the Digital Board Assembly and Shield Plate
(refer to Removing & Replacing the Digital Board Assembly & Shield Plate).
3 Unscrew the 4 mounting standoffs.
4 Unsolder the antenna connector cable.
5 Remove the RF Board Assembly.
To replace the RF Board Assembly:
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1. Reverse the steps taken to remove the RF Board Assembly.
Figure 4-Rf Board removal
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