HP 8568B Third Converter Adjustment, Figure 3-66.Minimum Image Response at 258.4 MHz, 16. Second IF Amplifier and Third Converter Adjustment

16. Second IF Amplifier and Third Converter Adjustment

Note Place the Markers as accurately as possible within the cursor markers for maximum frequency accuracy.

18.On the synthesized sweeper, press @G-X-n). M3 - M4 should read between 7 and 14 MHz.

19.On the synthesized sweeper, press [MKR] OFF and @iW] OFF.

20.Set the synthesized sweeper FREQUENCY MARKERS (M1) to 251.4 MHz and IIv12) to 351.4 MHz.

21.Set the Scalar Network Analyzer (ml to 10 dB and set IREF) (REF LEVEL) to + 14 dB. Set the REF POSN to one division down from the top.

22.Adjust A19C12 for minimum amplitude response at 258.4 MHz. Refer to Figure 3-64 for the location of the bandpass adjustments. Refer to Figure 3-66 for the typical response when the bandpass filter is properly adjusted.

2 8 0 MHz,

Figure 3-66. Minimum Image Response at 258.4 MHz

Note

Third Converter Adjustment

23.Repeat the adjustments in steps 13 and 22 to assure that the bandpass is between 7 MHz and 14 MHz and the image response at 258.4 MHz is minimized.

Remember to use the appropriate set up for steps 13 and 20.

24.Disconnect the cables from A19Jl and A19J2 and reconnect the instrument cables.

25.Disconnect cable 83 (gray/orange) from A20J3 and connect A20J3 to the input of HP 8566A/B Spectrum Analyzer, using a BNC to SMB test cable.

26.Press ~NSTR PRESET) on the HP 8566A/B Spectrum Analyzer, then

key in [CENTER FREQUENCY) 280 MHz, [FREQUENCY SPAN) 2 MHz. Set

MARKER [j), (REFERENCE) + 2 dBm, and [ENTER dB/DIv)

1dB.

27.Adjust A20 AMPTD A20Ll for maximum signal level as indicated on spectrum analyzer display.

28.Disconnect spectrum analyzer and reconnect cable 83 (gray/orange) to A20J3.

Adjustments 3-115