User Manual

SGD-SB2025NT-TUM, Part 1

Jan 12 Page 55 ALIGNMENT & TESTING

25. Connect the CTS to this lead and check that the RF local oscillator power is +17 dBm ± 2dB.

26. Measure the local oscillator frequency, this should be F

-90 MHz. Using a non-metallic

trimmer tool carefully adjust the TCXO (X2) frequency until the correct frequency is obtained.

27. Remove the test lead and solder S3 back in position.

28. Place the high frequency pick up loop in close proximity to IC1 in order to pick up the second

IF oscillator frequency (do not probe directly on the chip as test lead capacitance will affect

oscillator frequency).

29. Adjust CT1 for 89.545 MHz.

30. Inject an RF signal at -80 dBm (un-modulated) at F

into CN5 (Jumper I out, Jumper J in).

31. Measure the DC voltage at VF output SKD-3 and ensure it is 2.5 V. If necessary, adjust L14

for the required voltage.

32. Inject an RF signal at -80 dBm with standard modulation at F

into CN5.

33. Monitor the line Rx out and adjust T1 and T2 for minimum distortion.

34. Reduce the RF signal level and check that sensitivity is better than -112 dBm for 12 dB

SINAD.

35. Remove Jumper J and install Jumper I.

36. Inject an RF signal with standard modulation at F

into CN1.

37. Monitor the line Rx out and check that sensitivity is better than -117 dBm for 12 dB SINAD.

38. Repeat the IF Alignment test for the upper and lower channels.

6.2.3 Power Amplifier Module

Test Equipment Required

• Tested SB2025NT with PA removed.

• PC with MxTools software.

• RF Power Meter.

• RF Signal Generator.

• Multimeter.

• +13.8 VDC, 15 A Power Supply.

Preliminaries

1. On the MxTools Channel screen, program the upper, middle and lower frequencies of the

frequency band (refer to Appendix A for band split details) into three channels.

Note.

The ‘Continuous Update Enabled’ option on the MxTools Channel Edit screen should

be selected for these tests.

2. Do not connect the Exciter RF drive output CN1 to the PA.