HM135 Service Manual
Preliminary version Page 11 of 13
Radio contains a number of ESD, most sensitive components, without build-in protection are LDMOS
RF Power transistors.
1) Check connection between the Front Panel and the Main Unit.
2) Set ON/OFF Volume Potentiometer of the Front Panel Fully CCW (Switched Off)
3) Connect the radio’s Antenna connector to a Communication Tester, preset in Transmitter Measurement mode.
4) Set a Regulated Power Supply unit, capable to deliver at least 7A of DC Current, to 13.2V and current limit to 1A.
5) Connect the radio to the Power Supply Unit. Check the current. It must be below 30mA.
6) Switch ON the radio. Check the current, it must be below 0.5A.
7) Check Radio’s Internal Power Supply as follows:
Between pin 1 of DA7 (KIA7808API) (the pin, nearest to the Audio Amplifier IC) and ground – plus 13.2V
Between pin 3 of DA7 and ground – between 7.6 and 8.4V
Between the positive electrode of C247 and ground - between plus 4.75 and 5.25V
Between the positive electrode of C358 (near pin 1 of uP DD5) and ground plus 3.3, plus/minus 0.15V.
8) Switch off the radio.
3.4 Loading the Firmware
1) Connect a Firmware Programmer to the XP3, JTAG Connector.
2) Power On the radio
3) Load the firmware
4) Power Off the radio
5) Disconnect the Programmer.
6) Switch ON the Radio. Usually it will respond with
BAD CRC Message on LCD. It is OK. Switch OFF the Radio.
3.5 Programming the radio
1) Connect the programming cable to radio’s Microphone Connector.
2) Press the F1 key, keep it pressed and switch ON the radio. Radio will respond with
Programming... on the LCD and
Orange light of front panel diode. Release F1 Key.
3) Program the radio using Factorytest1.hpv settings file. It includes 6 channels:
CH1 - 135.100 MHz, 25 KHz Channel spacing, No CTCSS , No DCS, No Sellcall
CH2 - 155.100 MHz, another settings as per CH1
CH3 - 173.900 MHz, another settings are as per CH1
CH4 - 135.100 MHz, 12.5 KHz Channel spacing, No CTCSS , No DCS, No Sellcall
CH5 - 155.100 MHz, another settings as per CH 4
CH6 - 173.900 MHz, another settings are as per CH 4
CH7 - 155.1 MHz, 25 KHz spacing, CTCSS 67Hz on RX ant TX.
CH8 - 155.1 MHz, 25 KHz spacing, CTCSS 254.1 Hz.
CH9 - 155.1 MHz 25 KHz spacing , SELLCALL CCIR 12345 both RX ant TX
4) Switch OFF the radio and disconnect the programming cable.
5) Connect the microphone to the radio.
3.6 Setting the Power Amplifier Bias
1) Connect TP1, VCO voltage test point, to the ground.
2) Connect a 200 to 330 pF Disc Capacitor between the common point of VD16, VD17 and R98 and the ground.
3) Power ON the Radio. Push the PTT of the Microphone.
4) Note the current , it must be approx 400 to 500mA.
5) Turn slowly the RP5, TX Driver Bias in CW direction until the current from power supply is increased with approx. 300 mA.
Note the current.
6) Turn slowly RP6, TXPA Bias in CW direction until the current is increased with approx. 300mA. Keep the current absolute
value below 1.1 A.
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