6-10
Radio Alignment Procedures
: Transmitter Alignments
6.5.5
Transmit Deviation Balance Alignment
This alignment procedure balances the modulation contributions of the low- and high-frequency
portions of a baseband signal. Proper alignment is critical to the operation of signalling schemes that
have very low frequency components (for example, DPL) and could result in distorted waveforms if
improperly adjusted.
This procedure needs to be performed at multiple frequencies to allow for proper alignment across
the entire RF band. The RF band is divided into frequency zones with a calibration point (value) in
each zone.
NOTE:
This alignment is required after replacing (or servicing) the main board.
Proper alignment requires a modulation analyzer or meter with a frequency response to less than
10 Hz modulating frequency. The modulation analyzer settings during this test should be set for
average deviation, a 15 kHz low-pass filter, no de-emphasis, and no high-pass filter, if these settings
are supported.
This alignment can be done with either the R-2670 Communication Analyzer or the 8901_ Series
Modulation Analyzer. The method of choice is the R-2670 analyzer.
1. Initial setup using the R-2670 Communication Analyzer:
- Connect a BNC cable between the “DEMOD OUT” port and the “VERT/SINAD DIST/DMM
COUNTER IN” port on the R-2670.
- Press the
SPF
key on the R-2670 to display the “SPECIAL FUNCTIONS MENU.” Move the
cursor to “High Pass,” and select 5 Hz on the soft key menu. Select 20 kHz for the “Low
Pass” setting.
- In the “RF Control” section of the R-2670, move the cursor to the “B/W” setting and select
“WIDE +/- 100 kHz” on the soft key menu.
- Place the R-2670 cursor in the “Display” zone. Select “AC VOLTS” on the soft key menu.
Move the cursor to the “Range” setting and select “AUTO.”
2. Initial setup using the 8901_ Series Modulation Analyzer:
- Press the
FM MEASUREMENT
button. (The “
Error 0input level too low”
indication is
normal until an input signal is applied.)
- Simultaneously press the
Peak –
and
Peak +
buttons. Both LEDs on the buttons should
light.
- Press the 15 kHz LP filter key.
3. Select the
TX Deviation Balance
alignment screen. The screen indicates the transmit
frequencies to be used. See
.
4. In the "RF Control" section of the R2670, set the service Monitor to the desired frequency (as
shown in the frequency list in the TX Deviation Balance alignment screen).
5. Left-click the
PTT Tone: Low
button.
6. Left-click the slider of the frequency selected (should be the same frequency as step 4).
7. Left-click the
PTT Toggle
button on the screen to make the radio transmit. The screen
indicates whether the radio is transmitting.
8. Measure and Record the Low Tone Tx Deviation value from the 8901_ Series Analyzer or the
AC voltage value from the R2670.
9. Left-click the
PTT Tone: High
button.
10. Adjust the softpot value until the measured deviation/voltage, when using the high tone, is
/- 1.5% of the value observed when using the Low Tone.
Содержание APX 4000
Страница 1: ...APXTM TWO WAY RADIOS APX 1000 APX 2000 APX 4000 APX 4000Li BASIC SERVICE MANUAL ...
Страница 6: ...Notes iv Commercial Warranty ...
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Страница 46: ...3 12 Basic Theory of Operation Controller Section Notes ...
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Страница 128: ...8 34 Disassembly Reassembly Procedures Ensuring Radio Submergibility Notes ...
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Страница 255: ...Title Page ASTRO APX 1000 Digital Portable Radios Section 3 900 MHz APX 1000 ...
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Страница 350: ...Index 4 Index Notes ...
Страница 351: ...Title Page ASTRO APX APX 2000 APX 4000 Digital Portable Radios Section 4 APX 2000 APX 4000 Two Knobs ...
Страница 352: ...ii Notes ...
Страница 360: ...x Portable Radio Model Numbering System Notes ...
Страница 400: ...5 12 Performance Checks Transmitter Performance Checks Notes ...
Страница 427: ...Radio Alignment Procedures Performance Testing 6 27 Figure 6 34 Transmitter Test Pattern Screen 700 800 MHz ...
Страница 428: ...6 28 Radio Alignment Procedures Performance Testing Notes ...
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Страница 478: ...8 44 Disassembly Reassembly Procedures Ensuring Radio Submergibility Notes ...
Страница 488: ...10 6 Exploded Views and Parts Lists APX 2000 APX 4000 Two Knobs Back Kit Exploded View Parts List Notes ...
Страница 489: ...Title Page ASTRO APX 1000 APX 2000 APX 4000 APX 4000 Li Digital Portable Radios Section 5 Appendices ...
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Страница 492: ...A 2 Accessories Notes ...
Страница 496: ...Notes B 4 EMEA Warranty Service and Technical Support Further Assistance From Motorola ...
Страница 500: ...C 4 LACR Replacement Parts Ordering and Motorola Service Centers Motorola Service Centers Notes ...
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