Agilent Technologies 856290216 service manual MHz RF gain DAC value

9. Frequency Response Adjustment

Procedure

Note	The YIG-tuned filter/mixer slope and offset adjustment must be correct before
	the high band part of the frequency response adjustment can be done.

1.Connect the equipment as shown in Figure 2-17. Do not connect the HP 8482A power sensor to the HP 11667B power splitter.

2.Zero and calibrate the HP 8902A/HP 8482A combination in log mode (power levels read out in dBm) and connect the power sensor through an adapter to the power splitter.

3.Place the WR PROT/WR ENA jumper on the A2 controller assembly in the WR ENA position. The jumper is on the edge of the A2 board assembly and can be moved without folding the board down.

4.Press [PRESET) on the HP 85623 and set the controls as follows:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 MHz Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz Resolution bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 kHz dB/division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 dB

5.Press (INSTR PRESET) on the HP 8340A/B and set the controls as follows:

CWfrequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lO MHz Powerlevel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -4dBm

6.Set ref level cal DAC to zero. Press m), REF LVL ADJ and use the knob to set the value to 0. Press STORE REV LVL .

7.On the HP 85623, press (MKRI, (CAL), MORE i OF 2, SERVICE CAL DATA, then

FLATNESS . The current value of the RF Gain DAC should be displayed in the active function area.

8.Enter the appropriate power sensor calibration factor into the HP 8902A.

9.Set the HP 8340A/B m output to the frequency indicated in the active function area of the HP 85623 display. Adjust the HP 8340A/B POWER LEVEL for a -10 dBm reading on the HP 8902A.

10.On the HP 85623, adjust the RF gain DAC value using the front-panel knob or keypad until the marker reads -10 dBm fO.10 dB. Each DAC count results in an amplitude change of approximately 0.01 dB.

11.On the HP 85623, press @) to proceed to the next frequency.

12.Repeat steps 7 through 10 for all low-band frequencies 210 MHz.

13.Press m until 10 MHz is displayed in the active function block. Record the RF gain DAC value at 10 MHz.

10 MHz RF gain DAC value

Adjustment Procedures 2-45