6815854H01-A
June 15, 2005
Troubleshooting Procedures
: UHF Range 2 (450–520 MHz) Band Main Board Troubleshooting
4-17
4.8
UHF Range 2 (450–520 MHz) Band Main Board Troubleshooting
This information will help you troubleshoot the RF section of the UHF Range 2 (450–520 MHz) band
XTL 1500 radio. Use this information, along with the theory of operation and troubleshooting charts,
to diagnose and isolate the cause of failures.
Prior to troubleshooting, it is important to review the theory of operation, including specific
precautions and troubleshooting methods. Because much of the radio's circuitry operates at high
frequencies, measurements must be taken very carefully. Notes and cautions are added to the text
to alert you to this need in areas of greatest sensitivity. However, the need for extreme care does
exist in all measurements and tests.
4.8.1
Display Flashes “FAIL 001”
This display indicates a synthesizer “out-of-lock” condition. The following information will help to
trouble shoot the frequency generation unit to the component level. Perform the following checks to
determine the mode of the Fail 001:
1. Determine if the “out-of-lock” condition occurs in either receive mode, transmit mode, or both.
Also, check other frequencies programmed in the unit if available.
2. To determine if the “out-of-lock” is frequency or VCO dependant, place the unit into RF TEST
Mode, as described in the
ASTRO Digital XTL 1500 VHF/UHF Range 1/UHF Range 2/700–
800 MHz Mobile Radio Basic Service Manual
(6815853H01) and step through each test
channel.
indicates the frequency and Aux logic level for each test mode channel.
In addition,
provides information about the frequency of operation for
each VCO.
Table 4-10. Test Mode Channels UHF Range 2 (AUX 4 is not used for VCO selection in UHF)
Test
Mode
AUX (TX Logic)
TX
VCO
TX Freq
(MHz)
AUX (RX Logic)
RX
VCO
RX Freq
(MHz)
RX VCO
Freq
(MHz)
1
2
3
1
2
3
Chan 1
1
0
0
Q5826
450.025
0
0
1
Q5905
450.075
559.725
Chan 2
1
0
0
Q5826
455.825
0
0
1
Q5905
455.625
565.275
Chan 3
1
0
0
Q5826
463.675
0
0
1
Q5905
463.625
573.275
Chan 4
1
0
0
Q5826
473.375
1
1
0
Q5903
473.325
582.975
Chan 5
1
0
0
Q5826
484.975
1
1
0
Q5903
484.925
594.575
Chan 6
0
0
0
Q5825
485.025
1
1
0
Q5903
485.075
594.725
Chan 7
0
0
0
Q5825
490.825
1
1
0
Q5903
490.875
600.525
Chan 8
0
0
0
Q5825
496.625
0
1
0
Q5901
496.675
606.325
Chan 9
0
0
0
Q5825
508.375
0
1
0
Q5901
508.325
617.975
Chan 10
0
0
0
Q5825
519.975
0
1
0
Q5901
519.925
629.575
Содержание XTL 1500
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