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GTX LTR/Privacy Plus 800 MHz Mobile Service Manual
Transmitter Power
NOTE
During Tx POWER tuning, measure and
note the DC transmit current (I
each channel in the high power band.
1. Press F5 to select the Tx POWER calibration
softpot. The screen will indicate the transmit
test frequencies to be used.
2. Press F6 to key the radio.
3. Use the UP/DOWN arrow keys to adjust the
transmit power value.
4. Press Enter to select next softpot frequency.
5. Repeat steps 3 and 4 for the remaining test fre-
quencies.
6. Press F6 to dekey the radio.
7. Press F8 to program the value.
Transmit Current Limit
NOTE
Larger Softpot values yields increased
C U T B A C K r e s u l t i n g i n L O W E R
POWER.
1. After Tx POWER tuning the TRANSMIT CUR-
RENT LIMIT screen will appear. Select the fre-
quency with the highest DC transmit current
(I
) measured during the Tx POWER tuning
Tx
procuedure.
2. Press F6 to key the radio.
3. Use the UP/DOWN arrow keys to adjust the
DC transmit current value per Table 7-1.
Table 7-1. Transmit Current Limit Tune Windows
Model
800_15W
5.10 A
800_35W
I
Tx
4. Press F6 to dekey the radio.
5. Press F8 to program the value.
Transmit Deviation Balance
(Compensation) & Deviation Limit
Compensation alignment balances the modulation
sensitivity of the VCO and reference modulation (syn-
June, 2000
) for
Tx
Min
Max
5.50 A
+ 0.4 A
I
+ 1.0 A
Tx
thesizer low frequency port) lines. Compensation algo-
rithm is critical to the operation of signaling schemes
that have very low frequency components (e.g. DPL)
and could result in distorted waveforms if improperly
adjusted.
1.
Press F6 to select TX DEVIATION CALIBRA-
TION. The screen will indicate the transmit
test frequencies to be used.
2. Begin with the lowest test frequency shown on
the screen.
3. Press F6 to key the radio. Record this measure-
ment.
4. Press F4 to select 2.5 kHz.
5.
Use the UP/DOWN arrow keys to adjust the
deviation to within 0.5 dB of the value
recorded in step 3.
6. Press Enter to move to next softpot value.
7.
Repeat steps 5 and 6 for the remaining fre-
quencies.
8.
Press F8 to program the softpot value.
Transmit Deviation Limit
The transmit deviation limit softpot sets the maximum
deviation of the carrier. Tuning is performed for 25 kHz
channel spacing.
1.
Begin with the lowest test frequency shown on
the screen.
2.
Press F6 to key the radio.
3.
With Test Box 4460A: inject a 1 kHz tone, 2000
mVrms.
4.
Use the UP/DOWN arrow keys to adjust the
deviation to between 4.4 kHz and 4.8 kHz.
5.
Press Enter to move to the next softpot value.
6.
Repeat steps 4 and 5 for the remaining fre-
quencies shown on the screen.
7.
Press F6 to dekey the radio.
8.
Press F8 to program the softpot value.
Squelch
The squelch softpots set the signal to noise ratio at
which the squelch opens.
1.
Press F9 to select SQUELCH Adjustment.
2.
Adjust the UP/DOWN arrow key to the mini-
mum squelch value.
6880905Z99-O
Radio Tuning Procedure
Tuning Procedure
7-3
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