HP 8568B manual Location of 20 MHz Reference Adjustments

13. 20 MHz Reference Adjustments

Procedure 1. Position instrument on right side as shown in Figure 3-56 and remove bottom cover. Remove Al6 20 MHz Reference and install on extenders. See Figure 3-57 for the location of Al6 components.

2.Set LINE switch to ON and press (INSTR PRESET).

3.Set rear-panel FREQ REFERENCE INT/EXT switch to INT. Disconnect cable 2 (red) from A16Jl. Connect power meter to output of Time Base (A27Jl) using cable 2 (red). Note power meter indication for reference later.

dBm

4.Reconnect A27 Time Base output to A16Jl.

5.JumDer A16TP4 to Ground. Set the HP 8566A/B Spectrum Analyzer to [CENTER FREQUENCY) 20 MHz, [FREQUENCY SPAN) 1 MHz, CREFERENCE LEVEL) +20 dBm, and (RES] 100 kHz. Connect A16J3 to RF INPUT of HP 8566A/B Soectrum Analyzer and set [REFERENCE LEVEL) to place of signal at reference line (top graticule line).

6.Set HP 8566A/B Spectrum Analyzer to 1 dB/division SCALE and reset reference level to place peak of signal at reference line.

7.Connect DVM to A16TPl and ground to A22 TP12. Adjust Al6 COMB DRIVE A16R31 for DVM indication of > + 0.1 V dc. Disconnect DVM. (If DVM remains connected, it may load circuit.) See Figure 3-57 for location of adjustment.

Al6 20MHz R E F E R E N C E

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Figure 3-57. Location of 20 MHz Reference Adjustments

8.Adjust Al6 DOUBLER A16Tl to lower signal peak approximately 3 dB. Adjust Al6 CENTER FREQ A16Cll to peak signal on HP 8566A/B Spectrum Analyzer display. Next, adjust Al6 DOUBLER A16Tl for signal peak.

9.Disconnect cable 2 (red) from A16Jl and connect 500 OUTPUT of frequency synthesizer to A16Jl. Set FREQUENCY of frequency synthesizer to 10.17 MHz and set AMPLITUDE to + 3 dBm. Set HP

3-104 Adjustments