6881076C25-E
September 5, 2008
Troubleshooting Procedures
: VCO Procedures
4-17
4.3.2.4 No or Low Modulation
Under standard test conditions with a 1 kHz tone injected and 4.5 kHz deviation, there should be 700
mV (RMS) ±20% present on P0601-10. If this level is not present, troubleshoot the modulation circuit
on the carrier board and then troubleshoot the audio circuitry. If the proper level is present,
troubleshoot the modulation circuitry on the VCO kit. If no failure exists, replace the VCO.
Figure 4-2. VCO Block Diagram – UHF Band
OSC
BUFFER
1
2
3
4
5
6
9
10
11
12
GPW-5861-A
P0601
-8V
AUX1
AUX2
MODULATION
SYNTHESIZER
FEEDBACK
RX
INJECTION
(12 dBm TYPICAL)
* MEASURED WITH VCO OUTPUT
TERMINATED INTO 50 OHMS.
AUX1, AUX2 HIGH 8V
AUX1, AUX2 LOW 1V
>
_
<
_
PINSHIFT
CIRCUITRY
MODULATION
CIRCUITRY
1ST
BUFFER
2ND
BUFFER
X2
DOUBLER
FEEDBACK
BUFFER
SYNTH
ACTIVE
BIAS
P0601
8 dBm Typical*
TX
INJECTION
(16 dBm TYPICAL)
K9.4
9.6
8.6
+SL
-SL
Содержание ASTRO Digital Spectra
Страница 1: ...ASTRO Digital Spectra and Digital Spectra Plus UHF VHF 800 MHz Mobile Radios Detailed Service Manual ...
Страница 2: ......
Страница 6: ...September 5 2008 6881076C25 E iv Document History Notes ...
Страница 20: ...xviii List of Tables September 5 2008 6881076C25 E Notes ...
Страница 24: ...September 5 2008 6881076C25 E xxii CommercialWarranty Notes ...
Страница 48: ...September 5 2008 6881076C25 E xlvi Model Numbering Charts and Specifications Notes ...
Страница 142: ...September 5 2008 6881076C25 E 3 82 Theory of Operation Power Amplifiers Notes ...
Страница 218: ...September 5 2008 6881076C25 E 4 76 Troubleshooting Procedures Power Amplifier Procedures Notes ...
Страница 258: ...September 5 2008 6881076C25 E 6 14 Troubleshooting Waveforms ASTRO Digital Spectra Plus VOCON Board Waveforms Notes ...
Страница 434: ...September 5 2008 6881076C25 E Glossary 10 Notes ...
Страница 440: ...Index 6 September 5 2008 6881076C25 E Notes ...
Страница 441: ......