Operating instructions

Page 14 RF Technology R350/R500
6 ALIGNMENT PROCEDURE 6.1 Standard Input Signal
TCXO calibration may be required periodically due to crystal aging. The aging should
be less than 1 ppm/year.
6.1 Standard Input Signal
RF Signal Generator, 50Ω output impedance, Frequency range 350-520MHz, FM
modulation at 1kHz, deviation 1.5kHz peak for 12.5KHz channel spacing, 3.0kHz
peak for 25kHz channel spacing.
6.2 RF Alignment
1. Select center frequency channel. Measure dc Volts on test socket pin 9 to pin 1.
Adjust C61 to read 4.25 to 4.75V, with Alarm LED off.
2. Set signal generator to the center frequency channel frequency and connect to J1.
Modulation should be off. Measure the dc voltage on the test socket pins 7 to 1.
Adjust the generator level to get a reading of 1 - 2Vdc.
3. Set signal generator to the center frequency channel frequency and connect to J1.
Modulation should be off. Measure the dc voltage on the test socket pins 7 to 1.
Adjust FL1, FL2, and FL3 for maximum reading, reducing the generator output
to keep the voltage below 2Vdc.
6.3 IF Alignment
1. Set signal generator to the center frequency channel frequency and connect to J1.
Modulation should be off. Measure the dc voltage on the test socket pins 7 to 1.
Adjust the generator level to get a reading of 1-2Vdc.
2. Set signal generator to the center frequency channel frequency and connect to J1.
Modulation should be off. Measure the dc voltage on the test socket pins 7 to 1.
Adjust L5, L6, L7, L8 for maximum reading. Reduce generator output to keep
below 2 Vdc.
3. Set generator level to 10µV. Measure the frequency at U3 pin 9, and adjust L9
to obtain a frequency of 455kHz ±10Hz.
4. Set generator level to 1000µV (1mV), and switch the modulation on. Measure
the audio level at the test socket between pins 6 and 1. Adjust the line level
(RV3) to obtain approximately 1Vrms.
5. Maintain generator level at 1000µV (1mV), modulation on. Measure the audio
level at the test socket between pins 6 and 1. Adjust L10 for maximum reading.
6. Maintain generator level at 1000µV (1mV), modulation on. Measure the audio
level between pins 16 and 5 of P1. Adjust RV1 for 0.5Vrms.