Service manual

E. Transmit Deviation Balance
(Compensation) Alignment
Compensation alignment balances the modulation
sensitivity of the VCO and reference modulation (syn-
thesizer low-frequency port) lines. The compensation
algorithm is critical to the operation of signalling
schemes that have very-low-frequency components
(for example, DPL) and could result in distorted wave-
forms if improperly adjusted.
1. From the SERVICE MENU, press F2 to select the
TRANSMITTER ALIGNMENT MENU.
2. Press F4 to select the TRANSMIT DEVIATION
BALANCE (COMPENSATION) alignment screen.
The screen will indicate the transmit frequencies
to be used. See Figure 6.
3. Press Tab (or Enter or Return) to select a fre-
quency field (starting with the lowest frequency
shown).
4. Press F4. This will cause the radio to key and the
radio’s DSP IC to inject an 80Hz tone into the RF
board.
5. Measure the deviation and record this value.
6. Press F4 to dekey the radio.
7. Press F6. This will cause the radio’s DSP IC to
change the injection tone to 3kHz, 100mVrms.
Use the UP/DOWN arrow keys to adjust the devia-
tion to within ±2% of the value recorded in step 5.
8. Repeat steps 4-7 until the 3kHz tone deviation is
within ±2% of the 80Hz tone deviation.
9. Press F6 again to dekey the radio.
10. Press F8 to program the new softpot value.
11. Repeat steps 3-10 for the remaining frequencies.
12. Press F10 once to return to the TRANSMITTER
ALIGNMENT MENU, or press F10 twice to return
to the SERVICE MENU.
15
MOTOROLA Radio Service Software
ASTRO Model: H04UCH9PW7AN
MAIN:SERVICE:TX ALIGN:BAL ATTN
Use UP/DOWN Arrows To Adjust Softpot.
F1
HELP
F2 F3 F4
TOGGLE LOW
TONE PTT
F5 F6
TOGGLE HIGH
TONE PTT
F7 F8
PROGRAM
VALUE
F9 F10
EXIT
TRANSMIT DEVIATION BALANCE (COMPENSATION)
Current
Frequency Value New Softpot Value
450.62500 30 30
465.22500 30 30
475.22500 30 30
484.97500 45 45
500.27500 45 45
511.97500 45 45
Transmitter ..............Off
0
Min
63
Max
Figure 6. Transmit Deviation Balance (Compensation) Alignment Screen