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principles projects CNMI-Guam old projects |
MK3RXTestingCRX-8 MK-III receiver testing Power up first tests LED Voltages Signals Equipment needed: spectrum analyzer with 10 dB attenuator, or USB precision power meter; N to SMA and SMA to MCX cables,length 1 m, special 3-pin 1/10" jumper to SMA cable, programmable frequency generator, oscilloscope, VHDCI breakout board and cable. 27 MHz is typical frequency, for testing use the actual operating frequency of the radar. Signal levels in dBm are indicative, when tuning with potentiometer tune to 0.1 dB, when measuring other levels +- 1dB in power and +-10% in voltage are acceptable due to component tolerance. 1. check OCXO output on RADCELF, plug spectrum analyzer on connector: INT OSC P4: 8.3 dBm @ 100 MHz 2. run radcelf_ini_cal.sh to set the RADCELF to calibration mode (no chirp, 80 Hz off) 3. check output of DDS-A and DDS-B, plug spectrum analyzer successively on connectors: DDS-A I P19: 5 dBm @ 27 MHz DDS-A Q P21: 5 dBm @ 27 MHz DDS-B I P22: 5 dBm @ 27 MHz DDS-B Q P24: 5 dBm @ 27 MHz Adjust gray micro-potentiometers to these levels if needed. 4. check output of LO-DISTRIB: All outputs should be connected to 50 Ohm terminator or internal terminator jumper inserted, plug spectrum analyzer successively on MCX connectors: P4, P5, P7, P8, P9: -1.5 dBm @ 27 MHz Adjust TX output level to match TOMCO BTM-250SA, plug spectrum analyzer on SMA connectors and adjust blue potentiometer POT1: P10: -9 dBm @ 27 MHz 5. check LO levels on LO-BACKPLANE: Remove internal terminators JP10 and JP11, plug spectrum analyzer successively on MCX connectors J12 and J13, and adjust blue potentiometers POT1 and POT2: J12, J13: -1.5 dBm @ 27 MHz 6. check LO levels successively on each QRX board Using special jumper-to-coax cable, plug spectrum analyzer successively on LO-I (SPECQ3) and LO-Q (SPECQ3): LO-I, LO-Q: -14 dBm @ 27 MHz 7. program frequency generator for 27 MHz+80 Hz, -45 dBm (use attenuators on output as needed); plug frequency generator successively to each antenna input connector. 8. check RF signal level on each QRX board Using special jumper-to-coax cable, plug spectrum analyzer successively on TP1-0 (LNA) and SPECI1, SPECQ1 (mixer input): TP109 LNA: -36 dBm SPECI1, SPECQ1: -13.5 dBm 9. check demodulated signal level on each QRX board Using special jumper-to-coax cable, plug oscilloscope on 1 MOhm input to MIX-I and MIX-Q MIX-I JP5: 160mVpp MIX-Q JPQ5: 160mVpp 10. connect VHDCI-64 cable to breakout board, plug oscilloscope on each channel and check amplitude: OUTI3: 4.7Vpp OUTQ3: 4.7Vpp 11. acquire signal on D-Tacq |