19. Second Converter Adjustments

Procedure 1. Remove A23 RF Converter assembly from HP 8568B Spectrum Analyzer. Removal and installation procedures are contained as a repair procedure in the RF Section of the Troubleshooting and Repair Manual, Volume 1.

2.Position instrument on right side as shown in Figure 3-72 with the RF Converter removed but with cables still connected.

Second LO Frequency and Shift Adjustments

Note

3. Set HP 8568B Spectrum Analyzer LINE to ON and press

(JNSTR PRESET].

The second LO and pilot second LO output power is typically -35 dBm or less. An HP 8447F amplifier is used in steps 1 through 26 to amplify the LO power to a useable level for the counter and power meter.

Note The following adjustment tools are required to adjust the second converter: allen driver (08555-20121) and hex nut driver (08555-20122). Place the allen driver through the center hole of the hex nut driver. Loosen the adjustment nut using the hex nut driver while adjusting the bandpass with the allen driver. Do not over tighten the nut on the second converter.

4.Connect the amplifier’s input to A23A3J3 and the power meter to the amplifier’s output.

5.Adjust A23A3 2ND MIXER A23A3Z4 for maximum power meter indication. See Figure 3-73 for location of adjustment.

A23 R F C O N V E R T E R

2 0 5 2

5 MHz

2ND I F

B P F

 

z4,N,‘“LD

‘Zl Z2 Z3 L2’ 2HD Ml XER FREO

A23A3

2 0 1 7 . 6

MHz

2NO MIXEP

P I L O T 2ND

I F B P F

 

Figure 3-73. Location of Second Converter Adjustments

6.Disconnect power meter and connect frequency counter to amplifier’s output.

7.Adjust A23A3 2ND LO FREQ A23A3Z9 for frequency counter indication of 1748.6 MHz fl.O MHz. See Figure 3-73 for location of adjustment.

8.Disconnect frequency counter and reconnect power meter to amplifier’s output.

3-l 24 Adjustments