Service manual
ALIGNMENT AND TEST PROCEDURES
7-5
Month 2000
Part No. 001-2004-601
7.2.2 VOLTAGE MEASUREMENTS
Apply power to the Exciter by plugging the
20-pin cable from the RF Interface Board into J401.
Measure the voltages at the following pins.
U406, pin 1 +12V DC ±0.4V
U405, pin 1 +5V DC ±0.2V
U402, pin 1 +3.5V DC ±0.1V
U404, pin 7 +3.5V DC ±0.1V
7.2.3 PROGRAM TUNE-UP CHANNEL
For Exciters operating between:
406-424 MHz, 436-464 MHz or 476-506 MHz.
1. Using the PC and software, program the Synthe-
sizer for the Transmit frequency.
2. Use the "Turn on carrier" button to key the Exciter.
3. Tune the VCO capacitor C803 for +4.5V DC
±0.05V at TP1 (U403, pin 6).
Increase the transmit frequency by 3 MHz. The
voltage on TP1 shall be less than 7.5V.
Decrease the transmit frequency by 3 MHz. The
voltage on TP401 shall be greater than 2V.
4. Measure the Power Output of the Exciter at J402.
Reading should be > +18 dBm.
5. Use the "Turn on carrier" button to unkey the
Exciter.
For Transmitters operating within 6 MHz of the top of
the transmit band (424-430, 464-470 or 506-512 MHz).
1. Program the Synthesizer for the Highest transmit
frequency (i.e. 430, 470 or 512 MHz).
2. Use the "Turn on carrier" button to key the Exciter.
3. Set the control line voltage for 7.5V at TP1.
Check 6 MHz below the programmed frequency
(i.e. 424, 464 or 506 MHz) to verify that the control
voltage at TP1 is greater than 2V. The repeater
receiver can now be programmed for the desired
operating frequency.
4. Use the "Turn on carrier" button to unkey the
Exciter.
For Transmitters operating within 6 MHz of the bottom
of the transmit band (400-406, 430-436 or
470-476 MHz).
1. Program the Synthesizer for the Lowest transmit
frequency (i.e. 400, 430 or 470 MHz).
2. Set the control line voltage for 2V at TP1.
Check 6 MHz above the programmed frequency
(i.e. 406, 436 or 476 MHz) to verify that the control
voltage at TP1 is less than 7.5V. The repeater
receiver can now be programmed for the desired
operating frequency.
7.2.4 VCO TEST
1. The software programs the synthesizer for
3 MHz above the Tune-Up frequency.
2. Use the "Turn on carrier" button to key the Exciter.
3. The voltage on U403, pin 6 should be < 7V.
Power output should be > +18 dBm.
4. Use the "Turn on carrier" button to unkey the
Exciter.
5. The software programs the synthesizer for
3 MHz below the Tune-Up frequency.
6. Use the "Turn on carrier" button to key the Exciter.
7. The voltage on U403, pin 6 should be > 2.5V.
Power output should be > +18 dBm.
8. Use the "Turn on carrier" button to unkey the
Exciter.
9. The software programs the synthesizer for the
Transmit Channel.
7.2.5 TCXO FREQUENCY ADJUST
1. Connect a 10 dB pad and frequency counter to J402.
2. Use the "Turn on carrier" button to key the Exciter.
3. Tune TCXO Y401 for the Transmit Channel Fre-
quency, ± 50 Hz.
4. Use the "Turn on carrier" button to unkey the
Exciter.