HP 8568B manual LOG Offset Adjust, Set step attenuator to 40 dB

6.Video Processor Adjustments

6.Set step attenuator to 120 dB. DVM indication should be 0.000 *0.0005 V dc. (If DVM indication is out of tolerance, adjust A4A2R79 ZERO on the log amplifier-detector board..)

7.Set step attenuator to 0 dB.

8.Key in [Reference LWI) and adjust DATA knob for DVM indication as close to + 1.000 fO.OO1 V dc as possible. (It may be necessary to slightly adjust the front panel AMPTD CAL control to achieve required tolerance.)

9.Connect DVM to A4AlTP2.

10.Adjust A4AlR14 OS for a DVM indication of 0.000 f0.003 Vdc. See Figure 3-36 for the location of the adjustment.

		RI4	R36	R32
A4A1 Video P r o c e s s o r	LGR20S	OS	F S	Z E R O
\	\	\	\	I

A4A 1

Figure 3-36. Location of Video Processor Adjustments

11.Connect the DVM to A4AlTP3.

12.Set the step attenuator to 120 dB.

13.Adjust A4AlR32 ZERO for a DVM indication of 0.000 rtO.001 Vdc.

14.Set the step attenuator to 0 dB.

15.Adjust A4AlR36 FS for DVM indication of +2.000 f 0.001 V dc.

16.Repeat steps 12 through 15 until specifications of steps 13 and 15 are met.

LOG Offset Adjust

17.Set step attenuator to 40 dB.

18.Key in Cm), (m) I, LOG (ENTER dt3/mv), (SHIFT) [ENTER dB/DIv

q, PREFERENCE L E V E L ]-50 dBm.

19.Connect DVM to A4AlTPl. Record DVM indication. Indication should be approximately +0.500 V dc.

V de

20.Decrease reference level to -60 dBm using the step key.

21.Adjust A4AlR2 LG OS for DVM indication of +O.lOO +O.OOl V dc greater than the DVM indication recorded in step 19. See Figure 3-36 for location of adjustment.

3-70 Adjustments