Alignments

Cobra 150GTL (PFM-0089A-BB)


PLL CIRCUIT ALIGNMENT PROCEDURE


1. Set transceiver to 29.695 MHz Band D Display: 3.5
2. While in receive mode connect oscilloscope to TP 1
3. Adjust T 712 and observe DC level, then adjust the DC level to 6.95 to 7.0 Volts DC
4. Change to TX mode. Check DC level.
5. On RX mode connect oscilloscope to TP 2
6. Adjust T 713 for equal level at 26.065 (Band A, Display: 1) and 29.695 (Band D, Display 3.5)
7. Set receiver to 28.000 MHz
8. While in RX mode, connect frequency counter to TP 3
9. Set frequency to 29.695
10. Adjust trimmer CT1 to 19.000 MHz


CARRIER OSCILLATOR ALIGNMENT PROCEDURE



1. Set transceiver to 29.695 MHz
2. Press and hold mic key (PTT)
3. Adjust CT 2 to obtain 29.695 reading

 


RECEIVER ALIGNMENT PROCEDURE



1. Connect RF signal probe between ground and antenna point. Band: B, Display 40 (27.405)
2. Set SINAD of SSG to -47dBm and adjust: T 703, T 704, T 705, T 706, T 707, T 708, T 710 for maximum reading. Check for even sensitivity at: Band A, Display: .1 and Band D, Display: 3.5
3. Set SINAD of SSG to -47dBm and adjust T 702, for maximum reading

 


TRANSMITTER ALIGNMENT PROCEDURE



1. Set transceiver to 27.405 MHz Band: B Display: 40
2. Test Equipment Connection:
Connect RF power meter VTVM and oscilloscope to antenna jack
3. Adjust: T 718, T 719, T 720, T 721, T 722, T 723 to obtain maximum indication on VTVM
4. Change to frequency 26.065 MHz Band: A, Display: .1 and 29.695 MHz , Band : D, Display: 3.5
5. Adjust: T 721, T 722, T 723 to obtain maximum indication difference between 26.095 MHz and 29.695 MHz on the RF power meter
6. While on AM TX mode, no modulation and Hi/Lo power switch on High, adjust RV 9 to obtain RF carrier power of 4 watts on power meter
7. While on AM TX mode, no modulation and Lo/Hi power switch on High power, adjust RV 1 so that meter indicates +30
8. While on AM TX mode, AF signal 30 mV , adjust RV 12 to obtain 90% (negative) modulation
9. While on FM TX mode, AF signal 30mV, adjust RV 5 to obtain 2.5KHz deviation


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