HP406 Service Manual
Page 2 of 12
Contents
1 TECHNICAL SPECIFICATIONS .....................................................................................................................3
1.1 Test methods ............................................................................................................................................................3
1.2 Specifications table ...................................................................................................................................................3
2 CIRCUIT DESCRIPTION.................................................................................................................................4
2.1 General information...................................................................................................................................................4
2.2 Microprocessor/control..............................................................................................................................................4
2.3 VCO / Synthesizer (PLL)...........................................................................................................................................4
2.3.a Temperature-Compensated Crystal Oscillator (TCXO)..................................................................................................4
2.3.b Voltage-Controlled Oscillators .......................................................................................................................................4
2.3.c Synthesizer.......................................................................................................................................................................5
2.3.d Loop Filter.......................................................................................................................................................................5
2.4 Transmitter................................................................................................................................................................5
2.4.a RF Power Amplifier.........................................................................................................................................................5
2.4.b Antenna Switching...........................................................................................................................................................5
2.4.c Power control ..................................................................................................................................................................6
2.4.d Transmitter Audio Circuits..............................................................................................................................................6
2.4.e Audio Processing.............................................................................................................................................................6
2.5 Receiver....................................................................................................................................................................6
2.5.a Receiver Front End..........................................................................................................................................................6
2.5.b Local Oscillator (LO)......................................................................................................................................................6
2.5.c Mixer................................................................................................................................................................................6
2.5.d FM Detector and Squelch................................................................................................................................................6
2.5.e Receiver Audio Circuit ....................................................................................................................................................7
2.6 Signalling ..................................................................................................................................................................7
2.6.a General............................................................................................................................................................................7
2.6.b CTCSS Tone Encoder / Digital Code Squelch (DCS) Encoder.......................................................................................7
2.6.c Selective call....................................................................................................................................................................7
2.6.d Scrambler ........................................................................................................................................................................7
2.7 Battery.......................................................................................................................................................................8
3 ADJUSTMENTS ..............................................................................................................................................9
3.1 General .....................................................................................................................................................................9
3.2 Synthesizer/Transmitter VCO Check.........................................................................................................................9
3.2.a Frequency Adjustment.....................................................................................................................................................9
3.3 Transmitter Alignment...............................................................................................................................................9
3.3.a Power Adjustment............................................................................................................................................................9
3.3.b M odulation Adjustment ...................................................................................................................................................9
3.3.c CTCSS/DCS adjustment ................................................................................................................................................10
3.3.d Selcal adjustment...........................................................................................................................................................10
3.4 Receiver Alignment.................................................................................................................................................10
3.5 Figure 1 - Equipment Test set-up............................................................................................................................11
3.6 Figure 2 - Test adaptor............................................................................................................................................12
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