ALIGNMENT PROCEDURE
5-6
November 2001
Part No. 001-7240-001
connected to the accessory jack. Make sure that the
switch on the RPI is away from the LED so that it
indicates green.
The following sections describe the adjustments
that are made to align the transceiver.
5.5 FREQUENCY CHECK/ADJUST
NOTE: The transmitter immediately keys when the
following function is selected. To turn the transmitter
on and off, click the “Disable Transmit” button (see
screen which follows).
The transmit frequency should be checked with
the ambient temperature near the TCXO calibration
reference of 77° F (25° C). This ensures that the
frequency will be within tolerance at the temperature
extremes. At room temperature, this frequency should
be within ± 400 Hz. Checking the transmit frequency
also checks the receive frequency. Proceed as follows:
1. Connect a wattmeter and dummy load to the antenna
jack as shown in Figure 5-1.
2. Click the “Tune Entire Radio” button to automati-
cally step through all adjustments or click the “High
Power” button to perform only this adjustment.
3. Monitor the transmit frequency with a communica-
tions monitor set to the frequency displayed on the
screen.
4. If readjustment is required, the transceiver must be
opened to access the manual adjustment point as
described in Section 5.13. Adjust capacitor in
TCXO U201 for the correct frequency (see Figure
5-3).
5.6 HIGH RF POWER ADJUST
1. The high power test should already be selected for
the preceding adjustment.
2. Set the high power output for 4.0 watts at all data
points by clicking the Down/Down Fast or Up/Up
Fast buttons on the screen.
5.7 LOW RF POWER ADJUST
1. If manually selecting each test, click the “Low
Power” button in the screen shown in Figure 5-2.
Otherwise, this function is selected automatically
after completing the preceding High Power
adjustment.
2. Set the low power output for 1.0 watt at all data
points.
5.8 MODULATION BALANCE
1. If manually selecting each test, click the “Mod
Balance” button in the screen shown in Figure 5-2.
Otherwise, this function is selected automatically
after completing the Low Power adjustment.
2. View the transmit modulation waveform on the CRT
of a communication monitor. If applicable, set the
monitor for de-emphasis off, high-pass/bandpass
filter off, low-pass filter 15 kHz, and FM peak
detection active.
3. The detected signal should be a 100 Hz square wave
at a deviation of approximately 700 Hz. Follow the
instructions on the screen and adjust at all data
points for the best demodulated square wave with
minimum tilt and overshoot.
5.9 DATA DEVIATION
1. If manually selecting each test, click the “Data
Deviation” button in the screen shown in
Figure 5-2. Otherwise, this function is selected auto-
matically after completing the preceding Modula-
tion Balance adjustment.
2. Monitor the transmit modulation signal with a
communication monitor set as in the preceding step.
Adjust the wideband and narrow band data devia-
tion at all data points for the levels indicated on the
screen.
5.10 AUDIO DEVIATION
1. If manually selecting each test, click the “Audio
Deviation” button in the screen shown in
Figure 5-2. Otherwise, this function is selected auto-
matically after completing the preceding Data Devi-
ation adjustment.
