3. IF Bandpass Adjustment

Procedure

1.Set the HP 8560A m switch off and disconnect the power cord. Remove the analyzer cover and fold down the A2 Controller, A3 Interface, A4 Log Amp, and A5 IF assemblies. Reconnect the power cord and set the (LINE) switch on. Allow the analyzer to warm up for at least 30 minutes.

2.Connect the negative DVM lead to pin 6 of A5J6. See Figure 2-5. Set the HP 3456A controls as follows:

FUNCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DC VOLTS RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lOV

3.On the HP 8560A press (PRESET) (SPAN) 2 INIHz) LCAL) and IF ADJ OFF.

LC Bandpass Adjustments

4.On the HP 8560A, press ADJ CURR IF STATE. Wait for the IF ADJUST STATUS message to disappear before continuing with the next step.

5.Read the voltage on A5TP5 (this is an empty-hole type of test point). If the voltage is less than +6.06 Vdc, turn A5L300 LC CTR 1 clockwise. If the voltage is greater than t6.26 Vdc, turn LC CTR 1 counterclockwise.

6.Repeat steps 4 and 5 until the voltage reads t6.16 Vdc flO0 mV.

Note

If the range for the LC CTR adjustment is insufficient, replace the

 

appropriate factory-selected capacitor as listed in Table 2-6. To determine

 

the correct replacement value, center the LC CTR adjustment and press

 

ADJ CURR IF STATE. After the IF ADJUST STATUS message disappears, read

 

the DVM display. Choose a capacitor value from Table 2-7, based on the

 

DVM reading and the presently loaded capacitor value. Table 2-10 lists a few

 

capacitor part numbers.

 

 

Caution Set the HP 8560A m switch off before removing or replacing any shield.

7.Move the positive DVM lead to A5TP6.

8.Adjust A5L301 LC CTR 2 by repeating steps 4 through 6.

9.Move the positive DVM test lead to A5TPl (this is a resistor-lead type of test point).

10.Adjust A5L700 LC CTR 3 by repeating steps 4 through 6.

11.Move the positive DVM test lead to A5TP2 (this is a resistor-lead type of test point).

12.Adjust A5L702 LC CTR 4 using the procedure in steps 4 through 6.

Adjustment Procedures 2-21